Red Hat Enterprise Linux 8 Security Technical Implementation Guide

Checks: C-32891r567412_chk

Verify the operating system security patches and updates are installed and up to date. Updates are required to be applied with a frequency determined by the site or Program Management Office (PMO). Obtain the list of available package security updates from Red Hat. The URL for updates is https://rhn.redhat.com/errata/. It is important to note that updates provided by Red Hat may not be present on the system if the underlying packages are not installed. Check that the available package security updates have been installed on the system with the following command: $ sudo yum history list | more Loaded plugins: langpacks, product-id, subscription-manager ID | Command line | Date and time | Action(s) | Altered ------------------------------------------------------------------------------- 70 | install aide | 2020-03-05 10:58 | Install | 1 69 | update -y | 2020-03-04 14:34 | Update | 18 EE 68 | install vlc | 2020-02-21 17:12 | Install | 21 67 | update -y | 2020-02-21 17:04 | Update | 7 EE If package updates have not been performed on the system within the timeframe the site/program documentation requires, this is a finding. Typical update frequency may be overridden by Information Assurance Vulnerability Alert (IAVA) notifications from CYBERCOM. If the operating system is in non-compliance with the Information Assurance Vulnerability Management (IAVM) process, this is a finding.

Fix: F-32866r567413_fix

Install the operating system patches or updated packages available from Red Hat within 30 days or sooner as local policy dictates.

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Checks: C-32893r917863_chk

Verify RHEL 8 prevents unauthorized disclosure or modification of all information requiring at-rest protection by using disk encryption. If there is a documented and approved reason for not having data-at-rest encryption at the operating system level, such as encryption provided by a hypervisor or a disk storage array in a virtualized environment, this requirement is not applicable. Verify all system partitions are encrypted with the following command: $ sudo blkid /dev/mapper/rhel-root: UUID="67b7d7fe-de60-6fd0-befb-e6748cf97743" TYPE="crypto_LUKS" Every persistent disk partition present must be of type "crypto_LUKS". If any partitions other than the boot partition or pseudo file systems (such as /proc or /sys) are not type "crypto_LUKS", ask the administrator to indicate how the partitions are encrypted. If there is no evidence that these partitions are encrypted, this is a finding.

Fix: F-32868r567419_fix

Configure RHEL 8 to prevent unauthorized modification of all information at rest by using disk encryption. Encrypting a partition in an already installed system is more difficult, because existing partitions will need to be resized and changed. To encrypt an entire partition, dedicate a partition for encryption in the partition layout.

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Checks: C-32894r858693_chk

Verify any publicly accessible connection to the operating system displays the Standard Mandatory DoD Notice and Consent Banner before granting access to the system. Check for the location of the banner file being used with the following command: $ sudo grep -ir banner /etc/ssh/sshd_config* banner /etc/issue This command will return the banner keyword and the name of the file that contains the ssh banner (in this case "/etc/issue"). If the line is commented out, this is a finding. If conflicting results are returned, this is a finding. View the file specified by the banner keyword to check that it matches the text of the Standard Mandatory DoD Notice and Consent Banner: "You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only. By using this IS (which includes any device attached to this IS), you consent to the following conditions: -The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations. -At any time, the USG may inspect and seize data stored on this IS. -Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose. -This IS includes security measures (e.g., authentication and access controls) to protect USG interests--not for your personal benefit or privacy. -Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details." If the system does not display a graphical logon banner or the banner does not match the Standard Mandatory DoD Notice and Consent Banner, this is a finding. If the text in the file does not match the Standard Mandatory DoD Notice and Consent Banner, this is a finding.

Fix: F-32869r567422_fix

Configure the operating system to display the Standard Mandatory DoD Notice and Consent Banner before granting access to the system via the ssh. Edit the "/etc/ssh/sshd_config" file to uncomment the banner keyword and configure it to point to a file that will contain the logon banner (this file may be named differently or be in a different location if using a version of SSH that is provided by a third-party vendor). An example configuration line is: banner /etc/issue Either create the file containing the banner or replace the text in the file with the Standard Mandatory DoD Notice and Consent Banner. The DoD-required text is: "You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only. By using this IS (which includes any device attached to this IS), you consent to the following conditions: -The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations. -At any time, the USG may inspect and seize data stored on this IS. -Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose. -This IS includes security measures (e.g., authentication and access controls) to protect USG interests--not for your personal benefit or privacy. -Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details." The SSH service must be restarted for changes to take effect.

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Checks: C-32895r743914_chk

Verify RHEL 8 displays the Standard Mandatory DoD Notice and Consent Banner before granting access to the operating system via a graphical user logon. Note: This requirement assumes the use of the RHEL 8 default graphical user interface, Gnome Shell. If the system does not have any graphical user interface installed, this requirement is Not Applicable. Check that the operating system displays the exact Standard Mandatory DoD Notice and Consent Banner text with the command: $ sudo grep banner-message-text /etc/dconf/db/local.d/* banner-message-text= 'You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only.\nBy using this IS (which includes any device attached to this IS), you consent to the following conditions:\n-The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations.\n-At any time, the USG may inspect and seize data stored on this IS.\n-Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose.\n-This IS includes security measures (e.g., authentication and access controls) to protect USG interests--not for your personal benefit or privacy.\n-Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details. ' Note: The "\n " characters are for formatting only. They will not be displayed on the graphical interface. If the banner does not match the Standard Mandatory DoD Notice and Consent Banner exactly, this is a finding.

Fix: F-32870r743915_fix

Configure the operating system to display the Standard Mandatory DoD Notice and Consent Banner before granting access to the system. Note: If the system does not have a graphical user interface installed, this requirement is Not Applicable. Add the following lines to the [org/gnome/login-screen] section of the "/etc/dconf/db/local.d/01-banner-message": banner-message-text='You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only.\nBy using this IS (which includes any device attached to this IS), you consent to the following conditions:\n-The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations.\n-At any time, the USG may inspect and seize data stored on this IS.\n-Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose.\n-This IS includes security measures (e.g., authentication and access controls) to protect USG interests--not for your personal benefit or privacy.\n-Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details. ' Note: The "\n " characters are for formatting only. They will not be displayed on the graphical interface. Run the following command to update the database: $ sudo dconf update

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Checks: C-32896r567427_chk

Verify RHEL 8 displays the Standard Mandatory DoD Notice and Consent Banner before granting access to the operating system via a command line user logon. Check that RHEL 8 displays a banner at the command line login screen with the following command: $ sudo cat /etc/issue If the banner is set correctly it will return the following text: “You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only. By using this IS (which includes any device attached to this IS), you consent to the following conditions: -The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations. -At any time, the USG may inspect and seize data stored on this IS. -Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose. -This IS includes security measures (e.g., authentication and access controls) to protect USG interests--not for your personal benefit or privacy. -Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details.” If the banner text does not match the Standard Mandatory DoD Notice and Consent Banner exactly, this is a finding.

Fix: F-32871r567428_fix

Configure RHEL 8 to display the Standard Mandatory DoD Notice and Consent Banner before granting access to the system via command line logon. Edit the "/etc/issue" file to replace the default text with the Standard Mandatory DoD Notice and Consent Banner. The DoD-required text is: "You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only. By using this IS (which includes any device attached to this IS), you consent to the following conditions: -The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations. -At any time, the USG may inspect and seize data stored on this IS. -Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose. -This IS includes security measures (e.g., authentication and access controls) to protect USG interests -- not for your personal benefit or privacy. -Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details."

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Checks: C-32897r567430_chk

Verify that RHEL 8 monitors all remote access methods. Check that remote access methods are being logged by running the following command: $ sudo grep -E '(auth.*|authpriv.*|daemon.*)' /etc/rsyslog.conf auth.*;authpriv.*;daemon.* /var/log/secure If "auth.*", "authpriv.*" or "daemon.*" are not configured to be logged, this is a finding.

Fix: F-32872r567431_fix

Configure RHEL 8 to monitor all remote access methods by installing rsyslog with the following command: $ sudo yum install rsyslog Then add or update the following lines to the "/etc/rsyslog.conf" file: auth.*;authpriv.*;daemon.* /var/log/secure The "rsyslog" service must be restarted for the changes to take effect. To restart the "rsyslog" service, run the following command: $ sudo systemctl restart rsyslog.service

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Checks: C-32898r858738_chk

Verify RHEL 8 for PKI-based authentication has valid certificates by constructing a certification path (which includes status information) to an accepted trust anchor. Note: If the System Administrator demonstrates the use of an approved alternate multifactor authentication method, this requirement is not applicable. Check that the system has a valid DoD root CA installed with the following command: $ sudo openssl x509 -text -in /etc/sssd/pki/sssd_auth_ca_db.pem Certificate: Data: Version: 3 (0x2) Serial Number: 1 (0x1) Signature Algorithm: sha256WithRSAEncryption Issuer: C = US, O = U.S. Government, OU = DoD, OU = PKI, CN = DoD Root CA 3 Validity Not Before: Mar 20 18:46:41 2012 GMT Not After : Dec 30 18:46:41 2029 GMT Subject: C = US, O = U.S. Government, OU = DoD, OU = PKI, CN = DoD Root CA 3 Subject Public Key Info: Public Key Algorithm: rsaEncryption If the root ca file is not a DoD-issued certificate with a valid date and installed in the /etc/sssd/pki/sssd_auth_ca_db.pem location, this is a finding.

Fix: F-32873r809269_fix

Configure RHEL 8, for PKI-based authentication, to validate certificates by constructing a certification path (which includes status information) to an accepted trust anchor. Obtain a valid copy of the DoD root CA file from the PKI CA certificate bundle at cyber.mil and copy into the following file: /etc/sssd/pki/sssd_auth_ca_db.pem

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Checks: C-32899r567436_chk

Verify the SSH private key files have a passcode. For each private key stored on the system, use the following command: $ sudo ssh-keygen -y -f /path/to/file If the contents of the key are displayed, this is a finding.

Fix: F-32874r567437_fix

Create a new private and public key pair that utilizes a passcode with the following command: $ sudo ssh-keygen -n [passphrase]

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Checks: C-32900r567439_chk

Verify that the shadow password suite configuration is set to encrypt password with a FIPS 140-2 approved cryptographic hashing algorithm. Check the hashing algorithm that is being used to hash passwords with the following command: $ sudo grep -i crypt /etc/login.defs ENCRYPT_METHOD SHA512 If "ENCRYPT_METHOD" does not equal SHA512 or greater, this is a finding.

Fix: F-32875r567440_fix

Configure RHEL 8 to encrypt all stored passwords. Edit/Modify the following line in the "/etc/login.defs" file and set "[ENCRYPT_METHOD]" to SHA512. ENCRYPT_METHOD SHA512

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Checks: C-32901r567442_chk

Confirm that the interactive user account passwords are using a strong password hash with the following command: $ sudo cut -d: -f2 /etc/shadow $6$kcOnRq/5$NUEYPuyL.wghQwWssXRcLRFiiru7f5JPV6GaJhNC2aK5F3PZpE/BCCtwrxRc/AInKMNX3CdMw11m9STiql12f/ Password hashes "!" or "*" indicate inactive accounts not available for logon and are not evaluated. If any interactive user password hash does not begin with "$6$", this is a finding.

Fix: F-32876r567443_fix

Lock all interactive user accounts not using SHA-512 hashing until the passwords can be regenerated with SHA-512.

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Checks: C-32902r880704_chk

Check that a minimum number of hash rounds is configured by running the following command: $ sudo grep -E "^SHA_CRYPT_" /etc/login.defs If only one of "SHA_CRYPT_MIN_ROUNDS" or "SHA_CRYPT_MAX_ROUNDS" is set, and this value is below "5000", this is a finding. If both "SHA_CRYPT_MIN_ROUNDS" and "SHA_CRYPT_MAX_ROUNDS" are set, and the highest value for either is below "5000", this is a finding.

Fix: F-32877r809272_fix

Configure RHEL 8 to encrypt all stored passwords with a strong cryptographic hash. Edit/modify the following line in the "/etc/login.defs" file and set "SHA_CRYPT_MIN_ROUNDS" to a value no lower than "5000": SHA_CRYPT_MIN_ROUNDS 5000

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Checks: C-32905r743926_chk

Check to see if the system requires authentication for rescue mode with the following command: $ sudo grep sulogin-shell /usr/lib/systemd/system/rescue.service ExecStart=-/usr/lib/systemd/systemd-sulogin-shell rescue If the "ExecStart" line is configured for anything other than "/usr/lib/systemd/systemd-sulogin-shell rescue", commented out, or missing, this is a finding.

Fix: F-32880r743927_fix

Configure the system to require authentication upon booting into rescue mode by adding the following line to the "/usr/lib/systemd/system/rescue.service" file. ExecStart=-/usr/lib/systemd/systemd-sulogin-shell rescue

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Checks: C-32906r809274_chk

Verify that the pam_unix.so module is configured to use sha512. Check that the pam_unix.so module is configured to use sha512 in /etc/pam.d/password-auth with the following command: $ sudo grep password /etc/pam.d/password-auth | grep pam_unix password sufficient pam_unix.so sha512 If "sha512" is missing, or is commented out, this is a finding.

Fix: F-32881r809275_fix

Configure RHEL 8 to use a FIPS 140-2 approved cryptographic hashing algorithm for system authentication. Edit/modify the following line in the "/etc/pam.d/password-auth" file to include the sha512 option for pam_unix.so: password sufficient pam_unix.so sha512

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Checks: C-32907r646861_chk

Verify that RHEL 8 prevents system daemons from using Kerberos for authentication. If the system is a server utilizing krb5-server-1.17-18.el8.x86_64 or newer, this requirement is not applicable. If the system is a workstation utilizing krb5-workstation-1.17-18.el8.x86_64 or newer, this requirement is not applicable. Check if there are available keytabs with the following command: $ sudo ls -al /etc/*.keytab If this command produces any file(s), this is a finding.

Fix: F-32882r567461_fix

Configure RHEL 8 to prevent system daemons from using Kerberos for authentication. Remove any files with the .keytab extension from the operating system.

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Checks: C-32908r646863_chk

Verify the krb5-workstation package has not been installed on the system with the following commands: If the system is a server or is utilizing krb5-workstation-1.17-18.el8.x86_64 or newer, this is Not Applicable. $ sudo yum list installed krb5-workstation krb5-workstation.x86_64 1.17-9.el8 repository If the krb5-workstation package is installed and is not documented with the Information System Security Officer (ISSO) as an operational requirement, this is a finding.

Fix: F-32883r567464_fix

Document the krb5-workstation package with the ISSO as an operational requirement or remove it from the system with the following command: $ sudo yum remove krb5-workstation

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Checks: C-32909r567466_chk

Verify the operating system verifies correct operation of all security functions. Check if "SELinux" is active and in "Enforcing" mode with the following command: $ sudo getenforce Enforcing If "SELinux" is not active and not in "Enforcing" mode, this is a finding.

Fix: F-32884r567467_fix

Configure the operating system to verify correct operation of all security functions. Set the "SELinux" status and the "Enforcing" mode by modifying the "/etc/selinux/config" file to have the following line: SELINUX=enforcing A reboot is required for the changes to take effect.

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Checks: C-32912r792856_chk

Verify that all world-writable directories have the sticky bit set. Check to see that all world-writable directories have the sticky bit set by running the following command: $ sudo find / -type d \( -perm -0002 -a ! -perm -1000 \) -print 2>/dev/null drwxrwxrwt 7 root root 4096 Jul 26 11:19 /tmp If any of the returned directories are world-writable and do not have the sticky bit set, this is a finding.

Fix: F-32887r567476_fix

Configure all world-writable directories to have the sticky bit set to prevent unauthorized and unintended information transferred via shared system resources. Set the sticky bit on all world-writable directories using the command, replace "[World-Writable Directory]" with any directory path missing the sticky bit: $ sudo chmod 1777 [World-Writable Directory]

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Checks: C-32913r917865_chk

Verify the SSH server automatically terminates a user session after the SSH client has become unresponsive. Check that the "ClientAliveCountMax" is set to "1" by performing the following command: $ sudo grep -ir clientalivecountmax /etc/ssh/sshd_config* ClientAliveCountMax 1 If "ClientAliveCountMax" do not exist, is not set to a value of "1" in "/etc/ssh/sshd_config", or is commented out, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-32888r917866_fix

Note: This setting must be applied in conjunction with RHEL-08-010201 to function correctly. Configure the SSH server to terminate a user session automatically after the SSH client has become unresponsive. Modify or append the following lines in the "/etc/ssh/sshd_config" file: ClientAliveCountMax 1 For the changes to take effect, the SSH daemon must be restarted: $ sudo systemctl restart sshd.service

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Checks: C-32914r567481_chk

Verify that the "/var/log/messages" file has mode "0640" or less permissive with the following command: $ sudo stat -c "%a %n" /var/log/messages 640 /var/log/messages If a value of "0640" or less permissive is not returned, this is a finding.

Fix: F-32889r567482_fix

Change the permissions of the file "/var/log/messages" to "0640" by running the following command: $ sudo chmod 0640 /var/log/messages

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Checks: C-32915r567484_chk

Verify that the /var/log/messages file is owned by root with the following command: $ sudo stat -c "%U" /var/log/messages root If "root" is not returned as a result, this is a finding.

Fix: F-32890r567485_fix

Change the owner of the file /var/log/messages to root by running the following command: $ sudo chown root /var/log/messages

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Checks: C-32916r567487_chk

Verify the "/var/log/messages" file is group-owned by root with the following command: $ sudo stat -c "%G" /var/log/messages root If "root" is not returned as a result, this is a finding.

Fix: F-32891r567488_fix

Change the group of the file "/var/log/messages" to "root" by running the following command: $ sudo chgrp root /var/log/messages

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Checks: C-32917r567490_chk

Verify that the "/var/log" directory has a mode of "0755" or less with the following command: $ sudo stat -c "%a %n" /var/log 755 If a value of "0755" or less permissive is not returned, this is a finding.

Fix: F-32892r567491_fix

Change the permissions of the directory "/var/log" to "0755" by running the following command: $ sudo chmod 0755 /var/log

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Checks: C-32918r567493_chk

Verify the /var/log directory is owned by root with the following command: $ sudo stat -c "%U" /var/log root If "root" is not returned as a result, this is a finding.

Fix: F-32893r567494_fix

Change the owner of the directory /var/log to root by running the following command: $ sudo chown root /var/log

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Checks: C-32919r567496_chk

Verify the "/var/log" directory is group-owned by root with the following command: $ sudo stat -c "%G" /var/log root If "root" is not returned as a result, this is a finding.

Fix: F-32894r567497_fix

Change the group of the directory "/var/log" to "root" by running the following command: $ sudo chgrp root /var/log

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Checks: C-32920r917868_chk

Verify the SSH server is configured to use only MACs employing FIPS 140-2-approved algorithms with the following command: $ sudo grep -i macs /etc/crypto-policies/back-ends/opensshserver.config -oMACS=hmac-sha2-512,hmac-sha2-256,hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com If the MACs entries in the "opensshserver.config" file have any hashes other than shown here, the order differs from the example above, or they are missing or commented out, this is a finding.

Fix: F-32895r917869_fix

Configure the RHEL 8 SSH server to use only MACs employing FIPS 140-2-approved algorithms by updating the "/etc/crypto-policies/back-ends/opensshserver.config" file with the following line: -oMACS=hmac-sha2-512,hmac-sha2-256,hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com A reboot is required for the changes to take effect.

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Checks: C-32921r917871_chk

Verify the SSH server is configured to use only ciphers employing FIPS 140-2-approved algorithms with the following command: $ sudo grep -i ciphers /etc/crypto-policies/back-ends/opensshserver.config CRYPTO_POLICY='-oCiphers=aes256-ctr,aes192-ctr,aes128-ctr,aes256-gcm@openssh.com,aes128-gcm@openssh.com' If the cipher entries in the "opensshserver.config" file have any ciphers other than shown here, the order differs from the example above, or they are missing or commented out, this is a finding.

Fix: F-32896r917872_fix

Configure the RHEL 8 SSH server to use only ciphers employing FIPS 140-2-approved algorithms by updating the "/etc/crypto-policies/back-ends/opensshserver.config" file with the following line: -oCiphers=aes256-ctr,aes192-ctr,aes128-ctr,aes256-gcm@openssh.com,aes128-gcm@openssh.com A reboot is required for the changes to take effect.

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Checks: C-32923r567508_chk

Verify the OpenSSL library is configured to use only ciphers employing FIPS 140-2-approved algorithms: Verify that system-wide crypto policies are in effect: $ sudo grep -i opensslcnf.config /etc/pki/tls/openssl.cnf .include /etc/crypto-policies/back-ends/opensslcnf.config If the "opensslcnf.config" is not defined in the "/etc/pki/tls/openssl.cnf" file, this is a finding. Verify which system-wide crypto policy is in use: $ sudo update-crypto-policies --show FIPS If the system-wide crypto policy is set to anything other than "FIPS", this is a finding.

Fix: F-32898r567509_fix

Configure the RHEL 8 OpenSSL library to use only ciphers employing FIPS 140-2-approved algorithms with the following command: $ sudo fips-mode-setup --enable A reboot is required for the changes to take effect.

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Checks: C-32924r809380_chk

Verify the OpenSSL library is configured to use only DoD-approved TLS encryption: For versions prior to crypto-policies-20210617-1.gitc776d3e.el8.noarch: $ sudo grep -i MinProtocol /etc/crypto-policies/back-ends/opensslcnf.config MinProtocol = TLSv1.2 If the "MinProtocol" is set to anything older than "TLSv1.2", this is a finding. For version crypto-policies-20210617-1.gitc776d3e.el8.noarch and newer: $ sudo grep -i MinProtocol /etc/crypto-policies/back-ends/opensslcnf.config TLS.MinProtocol = TLSv1.2 DTLS.MinProtocol = DTLSv1.2 If the "TLS.MinProtocol" is set to anything older than "TLSv1.2" or the "DTLS.MinProtocol" is set to anything older than DTLSv1.2, this is a finding.

Fix: F-32899r809381_fix

Configure the RHEL 8 OpenSSL library to use only DoD-approved TLS encryption by editing the following line in the "/etc/crypto-policies/back-ends/opensslcnf.config" file: For versions prior to crypto-policies-20210617-1.gitc776d3e.el8.noarch: MinProtocol = TLSv1.2 For version crypto-policies-20210617-1.gitc776d3e.el8.noarch and newer: TLS.MinProtocol = TLSv1.2 DTLS.MinProtocol = DTLSv1.2 A reboot is required for the changes to take effect.

Generate Mitigation Statement:

Checks: C-32925r792858_chk

Verify the GnuTLS library is configured to only allow DoD-approved SSL/TLS Versions: $ sudo grep -io +vers.* /etc/crypto-policies/back-ends/gnutls.config +VERS-ALL:-VERS-DTLS0.9:-VERS-SSL3.0:-VERS-TLS1.0:-VERS-TLS1.1:-VERS-DTLS1.0:+COMP-NULL:%PROFILE_MEDIUM If the "gnutls.config" does not list "-VERS-DTLS0.9:-VERS-SSL3.0:-VERS-TLS1.0:-VERS-TLS1.1:-VERS-DTLS1.0" to disable unapproved SSL/TLS versions, this is a finding.

Fix: F-32900r567515_fix

Configure the RHEL 8 GnuTLS library to use only DoD-approved encryption by adding the following line to "/etc/crypto-policies/back-ends/gnutls.config": +VERS-ALL:-VERS-DTLS0.9:-VERS-SSL3.0:-VERS-TLS1.0:-VERS-TLS1.1:-VERS-DTLS1.0 A reboot is required for the changes to take effect.

Generate Mitigation Statement:

Checks: C-32926r792860_chk

Verify the system commands contained in the following directories have mode "755" or less permissive with the following command: $ sudo find -L /bin /sbin /usr/bin /usr/sbin /usr/local/bin /usr/local/sbin -perm /022 -exec ls -l {} \; If any system commands are found to be group-writable or world-writable, this is a finding.

Fix: F-32901r792861_fix

Configure the system commands to be protected from unauthorized access. Run the following command, replacing "[FILE]" with any system command with a mode more permissive than "755". $ sudo chmod 755 [FILE]

Generate Mitigation Statement:

Checks: C-32927r567520_chk

Verify the system commands contained in the following directories are owned by "root" with the following command: $ sudo find -L /bin /sbin /usr/bin /usr/sbin /usr/local/bin /usr/local/sbin ! -user root -exec ls -l {} \; If any system commands are returned, this is a finding.

Fix: F-32902r567521_fix

Configure the system commands to be protected from unauthorized access. Run the following command, replacing "[FILE]" with any system command file not owned by "root". $ sudo chown root [FILE]

Generate Mitigation Statement:

Checks: C-32928r792863_chk

Verify the system commands contained in the following directories are group-owned by "root", or a required system account, with the following command: $ sudo find -L /bin /sbin /usr/bin /usr/sbin /usr/local/bin /usr/local/sbin ! -group root -exec ls -l {} \; If any system commands are returned and is not group-owned by a required system account, this is a finding.

Fix: F-32903r567524_fix

Configure the system commands to be protected from unauthorized access. Run the following command, replacing "[FILE]" with any system command file not group-owned by "root" or a required system account. $ sudo chgrp root [FILE]

Generate Mitigation Statement:

Checks: C-32929r792865_chk

Verify the system-wide shared library files contained in the following directories have mode "755" or less permissive with the following command: $ sudo find -L /lib /lib64 /usr/lib /usr/lib64 -perm /022 -type f -exec ls -l {} \; If any system-wide shared library file is found to be group-writable or world-writable, this is a finding.

Fix: F-32904r792866_fix

Configure the library files to be protected from unauthorized access. Run the following command, replacing "[FILE]" with any library file with a mode more permissive than 755. $ sudo chmod 755 [FILE]

Generate Mitigation Statement:

Checks: C-32930r567529_chk

Verify the system-wide shared library files are owned by "root" with the following command: $ sudo find -L /lib /lib64 /usr/lib /usr/lib64 ! -user root -exec ls -l {} \; If any system wide shared library file is returned, this is a finding.

Fix: F-32905r567530_fix

Configure the system-wide shared library files (/lib, /lib64, /usr/lib and /usr/lib64) to be protected from unauthorized access. Run the following command, replacing "[FILE]" with any library file not owned by "root". $ sudo chown root [FILE]

Generate Mitigation Statement:

Checks: C-32931r567532_chk

Verify the system-wide shared library files are group-owned by "root" with the following command: $ sudo find -L /lib /lib64 /usr/lib /usr/lib64 ! -group root -exec ls -l {} \; If any system wide shared library file is returned and is not group-owned by a required system account, this is a finding.

Fix: F-32906r567533_fix

Configure the system-wide shared library files (/lib, /lib64, /usr/lib and /usr/lib64) to be protected from unauthorized access. Run the following command, replacing "[FILE]" with any library file not group-owned by "root". $ sudo chgrp root [FILE]

Generate Mitigation Statement:

Checks: C-32932r902714_chk

Verify the operating system routinely checks the baseline configuration for unauthorized changes and notifies the system administrator when anomalies in the operation of any security functions are discovered. Check that RHEL 8 routinely executes a file integrity scan for changes to the system baseline. The command used in the example will use a daily occurrence. Check the cron directories for scripts controlling the execution and notification of results of the file integrity application. For example, if AIDE is installed on the system, use the following commands: $ sudo ls -al /etc/cron.* | grep aide -rwxr-xr-x 1 root root 29 Nov 22 2015 aide $ sudo grep aide /etc/crontab /var/spool/cron/root /etc/crontab: 30 04 * * * root /usr/sbin/aide /var/spool/cron/root: 30 04 * * * root /usr/sbin/aide $ sudo more /etc/cron.daily/aide #!/bin/bash /usr/sbin/aide --check | /bin/mail -s "$HOSTNAME - Daily AIDE integrity check run" root@example_server_name.mil If the file integrity application does not exist, or a script file controlling the execution of the file integrity application does not exist, or the file integrity application does not notify designated personnel of changes, this is a finding.

Fix: F-32907r902715_fix

Configure the file integrity tool to run automatically on the system at least weekly and to notify designated personnel if baseline configurations are changed in an unauthorized manner. The AIDE tool can be configured to email designated personnel with the use of the cron system. The following example output is generic. It will set cron to run AIDE daily and to send email at the completion of the analysis. $ sudo more /etc/cron.daily/aide #!/bin/bash /usr/sbin/aide --check | /bin/mail -s "$HOSTNAME - Daily AIDE integrity check run" root@example_server_name.mil Note: Per requirement RHEL-08-010358, the "mailx" package must be installed on the system to enable email functionality.

Generate Mitigation Statement:

Checks: C-32935r858746_chk

Verify the operating system is configured to disable kernel image loading with the following commands: Check the status of the kernel.kexec_load_disabled kernel parameter. $ sudo sysctl kernel.kexec_load_disabled kernel.kexec_load_disabled = 1 If "kernel.kexec_load_disabled" is not set to "1" or is missing, this is a finding. Check that the configuration files are present to enable this kernel parameter. $ sudo grep -r kernel.kexec_load_disabled /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf /lib/sysctl.d/*.conf /etc/sysctl.conf /etc/sysctl.d/*.conf /etc/sysctl.d/99-sysctl.conf:kernel.kexec_load_disabled = 1 If "kernel.kexec_load_disabled" is not set to "1", is missing or commented out, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-32910r858747_fix

Configure the operating system to disable kernel image loading. Add or edit the following line in a system configuration file, in the "/etc/sysctl.d/" directory: kernel.kexec_load_disabled = 1 Remove any configurations that conflict with the above from the following locations: /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf /lib/sysctl.d/*.conf /etc/sysctl.conf /etc/sysctl.d/*.conf Load settings from all system configuration files with the following command: $ sudo sysctl --system

Generate Mitigation Statement:

Checks: C-32936r858749_chk

Verify the operating system is configured to enable DAC on symlinks with the following commands: Check the status of the fs.protected_symlinks kernel parameter. $ sudo sysctl fs.protected_symlinks fs.protected_symlinks = 1 If "fs.protected_symlinks" is not set to "1" or is missing, this is a finding. Check that the configuration files are present to enable this kernel parameter. $ sudo grep -r fs.protected_symlinks /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf /lib/sysctl.d/*.conf /etc/sysctl.conf /etc/sysctl.d/*.conf /etc/sysctl.d/99-sysctl.conf:fs.protected_symlinks = 1 If "fs.protected_symlinks" is not set to "1", is missing or commented out, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-32911r858750_fix

Configure the operating system to enable DAC on symlinks. Add or edit the following line in a system configuration file, in the "/etc/sysctl.d/" directory: fs.protected_symlinks = 1 Remove any configurations that conflict with the above from the following locations: /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf /lib/sysctl.d/*.conf /etc/sysctl.conf /etc/sysctl.d/*.conf Load settings from all system configuration files with the following command: $ sudo sysctl --system

Generate Mitigation Statement:

Checks: C-32937r858752_chk

Verify the operating system is configured to enable DAC on hardlinks with the following commands: Check the status of the fs.protected_hardlinks kernel parameter. $ sudo sysctl fs.protected_hardlinks fs.protected_hardlinks = 1 If "fs.protected_hardlinks" is not set to "1" or is missing, this is a finding. Check that the configuration files are present to enable this kernel parameter. $ sudo grep -r fs.protected_hardlinks /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf /lib/sysctl.d/*.conf /etc/sysctl.conf /etc/sysctl.d/*.conf /etc/sysctl.d/99-sysctl.conf:fs.protected_hardlinks = 1 If "fs.protected_hardlinks" is not set to "1", is missing or commented out, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-32912r858753_fix

Configure the operating system to enable DAC on hardlinks. Add or edit the following line in a system configuration file, in the "/etc/sysctl.d/" directory: fs.protected_hardlinks = 1 Remove any configurations that conflict with the above from the following locations: /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf /lib/sysctl.d/*.conf /etc/sysctl.conf /etc/sysctl.d/*.conf Load settings from all system configuration files with the following command: $ sudo sysctl --system

Generate Mitigation Statement:

Checks: C-32940r854024_chk

Verify that "/etc/sudoers" has no occurrences of "NOPASSWD". Check that the "/etc/sudoers" file has no occurrences of "NOPASSWD" by running the following command: $ sudo grep -i nopasswd /etc/sudoers /etc/sudoers.d/* %admin ALL=(ALL) NOPASSWD: ALL If any occurrences of "NOPASSWD" are returned from the command and have not been documented with the ISSO as an organizationally defined administrative group utilizing MFA, this is a finding.

Fix: F-32915r854025_fix

Remove any occurrence of "NOPASSWD" found in "/etc/sudoers" file or files in the "/etc/sudoers.d" directory.

Generate Mitigation Statement:

Checks: C-32941r567562_chk

Verify that "/etc/sudoers" has no occurrences of "!authenticate". Check that the "/etc/sudoers" file has no occurrences of "!authenticate" by running the following command: $ sudo grep -i !authenticate /etc/sudoers /etc/sudoers.d/* If any occurrences of "!authenticate" return from the command, this is a finding.

Fix: F-32916r567563_fix

Remove any occurrence of "!authenticate" found in "/etc/sudoers" file or files in the "/etc/sudoers.d" directory.

Generate Mitigation Statement:

Checks: C-32942r743941_chk

Verify the operating system has the packages required for multifactor authentication installed with the following commands: $ sudo yum list installed openssl-pkcs11 openssl-pkcs11.x86_64 0.4.8-2.el8 @anaconda If the "openssl-pkcs11" package is not installed, ask the administrator to indicate what type of multifactor authentication is being utilized and what packages are installed to support it. If there is no evidence of multifactor authentication being used, this is a finding.

Fix: F-32917r743942_fix

Configure the operating system to implement multifactor authentication by installing the required package with the following command: $ sudo yum install openssl-pkcs11

Generate Mitigation Statement:

Checks: C-32943r858740_chk

Verify the operating system implements certificate status checking for multifactor authentication. Note: If the System Administrator demonstrates the use of an approved alternate multifactor authentication method, this requirement is not applicable. Check to see if Online Certificate Status Protocol (OCSP) is enabled and using the proper digest value on the system with the following command: $ sudo grep certificate_verification /etc/sssd/sssd.conf /etc/sssd/conf.d/*.conf | grep -v "^#" certificate_verification = ocsp_dgst=sha1 If the certificate_verification line is missing from the [sssd] section, or is missing "ocsp_dgst=sha1", ask the administrator to indicate what type of multifactor authentication is being utilized and how the system implements certificate status checking. If there is no evidence of certificate status checking being used, this is a finding.

Fix: F-32918r809280_fix

Configure the operating system to implement certificate status checking for multifactor authentication. Review the "/etc/sssd/sssd.conf" file to determine if the system is configured to prevent OCSP or certificate verification. Add the following line to the [sssd] section of the "/etc/sssd/sssd.conf" file: certificate_verification = ocsp_dgst=sha1 The "sssd" service must be restarted for the changes to take effect. To restart the "sssd" service, run the following command: $ sudo systemctl restart sssd.service

Generate Mitigation Statement:

Checks: C-32944r567571_chk

Verify RHEL 8 accepts PIV credentials. Check that the "opensc" package is installed on the system with the following command: $ sudo yum list installed opensc opensc.x86_64 0.19.0-5.el8 @anaconda Check that "opensc" accepts PIV cards with the following command: $ sudo opensc-tool --list-drivers | grep -i piv PIV-II Personal Identity Verification Card If the "opensc" package is not installed and the "opensc-tool" driver list does not include "PIV-II", this is a finding.

Fix: F-32919r567572_fix

Configure RHEL 8 to accept PIV credentials. Install the "opensc" package using the following command: $ sudo yum install opensc

Generate Mitigation Statement:

Checks: C-32945r567574_chk

Verify the NX (no-execution) bit flag is set on the system. Check that the no-execution bit flag is set with the following commands: $ sudo dmesg | grep NX [ 0.000000] NX (Execute Disable) protection: active If "dmesg" does not show "NX (Execute Disable) protection" active, check the cpuinfo settings with the following command: $ sudo less /proc/cpuinfo | grep -i flags flags : fpu vme de pse tsc ms nx rdtscp lm constant_tsc If "flags" does not contain the "nx" flag, this is a finding.

Fix: F-32920r567575_fix

The NX bit execute protection must be enabled in the system BIOS.

Generate Mitigation Statement:

Checks: C-32946r792883_chk

Verify that GRUB 2 is configured to enable page poisoning to mitigate use-after-free vulnerabilities with the following commands: Check that the current GRUB 2 configuration has page poisoning enabled: $ sudo grub2-editenv list | grep page_poison kernelopts=root=/dev/mapper/rhel-root ro crashkernel=auto resume=/dev/mapper/rhel-swap rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap rhgb quiet fips=1 page_poison=1 vsyscall=none audit=1 audit_backlog_limit=8192 boot=UUID=8d171156-cd61-421c-ba41-1c021ac29e82 If "page_poison" is not set to "1" or is missing, this is a finding. Check that page poisoning is enabled by default to persist in kernel updates: $ sudo grep page_poison /etc/default/grub GRUB_CMDLINE_LINUX="page_poison=1" If "page_poison" is not set to "1", is missing or commented out, this is a finding.

Fix: F-32921r567578_fix

Configure RHEL 8 to enable page poisoning with the following commands: $ sudo grubby --update-kernel=ALL --args="page_poison=1" Add or modify the following line in "/etc/default/grub" to ensure the configuration survives kernel updates: GRUB_CMDLINE_LINUX="page_poison=1"

Generate Mitigation Statement:

Checks: C-32947r792885_chk

Verify that GRUB 2 is configured to disable vsyscalls with the following commands: Check that the current GRUB 2 configuration disables vsyscalls: $ sudo grub2-editenv list | grep vsyscall kernelopts=root=/dev/mapper/rhel-root ro crashkernel=auto resume=/dev/mapper/rhel-swap rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap rhgb quiet fips=1 page_poison=1 vsyscall=none audit=1 audit_backlog_limit=8192 boot=UUID=8d171156-cd61-421c-ba41-1c021ac29e82 If "vsyscall" is not set to "none" or is missing, this is a finding. Check that vsyscalls are disabled by default to persist in kernel updates: $ sudo grep vsyscall /etc/default/grub GRUB_CMDLINE_LINUX="vsyscall=none" If "vsyscall" is not set to "none", is missing or commented out and is not documented with the Information System Security Officer (ISSO) as an operational requirement, this is a finding.

Fix: F-32922r743947_fix

Document the use of vsyscalls with the ISSO as an operational requirement or disable them with the following command: $ sudo grubby --update-kernel=ALL --args="vsyscall=none" Add or modify the following line in "/etc/default/grub" to ensure the configuration survives kernel updates: GRUB_CMDLINE_LINUX="vsyscall=none"

Generate Mitigation Statement:

Checks: C-32948r792887_chk

Verify that GRUB 2 is configured to enable poisoning of SLUB/SLAB objects to mitigate use-after-free vulnerabilities with the following commands: Check that the current GRUB 2 configuration has poisoning of SLUB/SLAB objects enabled: $ sudo grub2-editenv list | grep slub_debug kernelopts=root=/dev/mapper/rhel-root ro crashkernel=auto resume=/dev/mapper/rhel-swap rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap rhgb quiet fips=1 slub_debug=P page_poison=1 vsyscall=none audit=1 audit_backlog_limit=8192 boot=UUID=8d171156-cd61-421c-ba41-1c021ac29e82 If "slub_debug" is not set to "P" or is missing, this is a finding. Check that poisoning of SLUB/SLAB objects is enabled by default to persist in kernel updates: $ sudo grep slub_debug /etc/default/grub GRUB_CMDLINE_LINUX="slub_debug=P" If "slub_debug" is not set to "P", is missing or commented out, this is a finding.

Fix: F-32923r567584_fix

Configure RHEL 8 to enable poisoning of SLUB/SLAB objects with the following commands: $ sudo grubby --update-kernel=ALL --args="slub_debug=P" Add or modify the following line in "/etc/default/grub" to ensure the configuration survives kernel updates: GRUB_CMDLINE_LINUX="slub_debug=P"

Generate Mitigation Statement:

Checks: C-32949r858765_chk

Verify RHEL 8 implements ASLR with the following command: $ sudo sysctl kernel.randomize_va_space kernel.randomize_va_space = 2 If "kernel.randomize_va_space" is not set to "2", this is a finding. Check that the configuration files are present to enable this kernel parameter. $ sudo grep -r kernel.randomize_va_space /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf /lib/sysctl.d/*.conf /etc/sysctl.conf /etc/sysctl.d/*.conf /etc/sysctl.d/99-sysctl.conf:kernel.randomize_va_space = 2 If "kernel.randomize_va_space" is not set to "2", is missing or commented out, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-32924r858766_fix

Configure the operating system to implement virtual address space randomization. Add or edit the following line in a system configuration file, in the "/etc/sysctl.d/" directory: kernel.randomize_va_space=2 Remove any configurations that conflict with the above from the following locations: /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf /lib/sysctl.d/*.conf /etc/sysctl.conf /etc/sysctl.d/*.conf Issue the following command to make the changes take effect: $ sudo sysctl --system

Generate Mitigation Statement:

Checks: C-32951r567592_chk

Ensure the operating system verifies correct operation of all security functions. Check if "SELinux" is active and is enforcing the targeted policy with the following command: $ sudo sestatus SELinux status: enabled SELinuxfs mount: /sys/fs/selinux SELinux root directory: /etc/selinux Loaded policy name: targeted Current mode: enforcing Mode from config file: enforcing Policy MLS status: enabled Policy deny_unknown status: allowed Memory protection checking: actual (secure) Max kernel policy version: 31 If the "Loaded policy name" is not set to "targeted", this is a finding. Verify that the /etc/selinux/config file is configured to the "SELINUXTYPE" to "targeted": $ sudo grep -i "selinuxtype" /etc/selinux/config | grep -v '^#' SELINUXTYPE = targeted If no results are returned or "SELINUXTYPE" is not set to "targeted", this is a finding.

Fix: F-32926r567593_fix

Configure the operating system to verify correct operation of all security functions. Set the "SELinuxtype" to the "targeted" policy by modifying the "/etc/selinux/config" file to have the following line: SELINUXTYPE=targeted A reboot is required for the changes to take effect.

Generate Mitigation Statement:

Checks: C-32955r567604_chk

Verify the SSH public host key files have mode "0644" or less permissive with the following command: $ sudo ls -l /etc/ssh/*.pub -rw-r--r-- 1 root root 618 Nov 28 06:43 ssh_host_dsa_key.pub -rw-r--r-- 1 root root 347 Nov 28 06:43 ssh_host_key.pub -rw-r--r-- 1 root root 238 Nov 28 06:43 ssh_host_rsa_key.pub If any key.pub file has a mode more permissive than "0644", this is a finding. Note: SSH public key files may be found in other directories on the system depending on the installation.

Fix: F-32930r567605_fix

Change the mode of public host key files under "/etc/ssh" to "0644" with the following command: $ sudo chmod 0644 /etc/ssh/*key.pub The SSH daemon must be restarted for the changes to take effect. To restart the SSH daemon, run the following command: $ sudo systemctl restart sshd.service

Generate Mitigation Statement:

Checks: C-32956r880712_chk

Verify the SSH private host key files have mode "0640" or less permissive with the following command: $ sudo ls -l /etc/ssh/ssh_host*key -rw-r----- 1 root ssh_keys 668 Nov 28 06:43 ssh_host_dsa_key -rw-r----- 1 root ssh_keys 582 Nov 28 06:43 ssh_host_key -rw-r----- 1 root ssh_keys 887 Nov 28 06:43 ssh_host_rsa_key If any private host key file has a mode more permissive than "0640", this is a finding.

Fix: F-32931r880713_fix

Configure the mode of SSH private host key files under "/etc/ssh" to "0640" with the following command: $ sudo chmod 0640 /etc/ssh/ssh_host*key The SSH daemon must be restarted for the changes to take effect. To restart the SSH daemon, run the following command: $ sudo systemctl restart sshd.service

Generate Mitigation Statement:

Checks: C-32957r858700_chk

Verify the SSH daemon performs strict mode checking of home directory configuration files with the following command: $ sudo grep -ir strictmodes /etc/ssh/sshd_config* StrictModes yes If "StrictModes" is set to "no", is missing, or the returned line is commented out, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-32932r567611_fix

Configure SSH to perform strict mode checking of home directory configuration files. Uncomment the "StrictModes" keyword in "/etc/ssh/sshd_config" and set the value to "yes": StrictModes yes The SSH daemon must be restarted for the changes to take effect. To restart the SSH daemon, run the following command: $ sudo systemctl restart sshd.service

Generate Mitigation Statement:

Checks: C-32959r858704_chk

Verify the SSH daemon does not allow authentication using known host’s authentication with the following command: $ sudo grep -ir IgnoreUserKnownHosts /etc/ssh/sshd_config* IgnoreUserKnownHosts yes If the value is returned as "no", the returned line is commented out, or no output is returned, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-32934r567617_fix

Configure the SSH daemon to not allow authentication using known host’s authentication. Add the following line in "/etc/ssh/sshd_config", or uncomment the line and set the value to "yes": IgnoreUserKnownHosts yes The SSH daemon must be restarted for the changes to take effect. To restart the SSH daemon, run the following command: $ sudo systemctl restart sshd.service

Generate Mitigation Statement:

Checks: C-32960r858706_chk

Verify the SSH daemon does not allow Kerberos authentication with the following command: $ sudo grep -ir KerberosAuthentication /etc/ssh/sshd_config* KerberosAuthentication no If the value is returned as "yes", the returned line is commented out, no output is returned, or has not been documented with the ISSO, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-32935r743956_fix

Configure the SSH daemon to not allow Kerberos authentication. Add the following line in "/etc/ssh/sshd_config", or uncomment the line and set the value to "no": KerberosAuthentication no The SSH daemon must be restarted for the changes to take effect. To restart the SSH daemon, run the following command: $ sudo systemctl restart sshd.service

Generate Mitigation Statement:

Checks: C-32964r567631_chk

Verify that a separate file system/partition has been created for non-privileged local interactive user home directories. $ sudo grep /tmp /etc/fstab /dev/mapper/rhel-tmp /tmp xfs defaults,nodev,nosuid,noexec 0 0 If a separate entry for the file system/partition "/tmp" does not exist, this is a finding.

Fix: F-32939r567632_fix

Migrate the "/tmp" directory onto a separate file system/partition.

Generate Mitigation Statement:

Checks: C-32965r858710_chk

Verify remote access using SSH prevents users from logging on directly as "root". Check that SSH prevents users from logging on directly as "root" with the following command: $ sudo grep -ir PermitRootLogin /etc/ssh/sshd_config* PermitRootLogin no If the "PermitRootLogin" keyword is set to "yes", is missing, or is commented out, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-32940r567635_fix

Configure RHEL 8 to stop users from logging on remotely as the "root" user via SSH. Edit the appropriate "/etc/ssh/sshd_config" file to uncomment or add the line for the "PermitRootLogin" keyword and set its value to "no": PermitRootLogin no The SSH daemon must be restarted for the changes to take effect. To restart the SSH daemon, run the following command: $ sudo systemctl restart sshd.service

Generate Mitigation Statement:

Checks: C-32967r567640_chk

Verify the rsyslog service is enabled and active with the following commands: $ sudo systemctl is-enabled rsyslog enabled $ sudo systemctl is-active rsyslog active If the service is not "enabled" and "active" this is a finding.

Fix: F-32942r567641_fix

Start the auditd service, and enable the rsyslog service with the following commands: $ sudo systemctl start rsyslog.service $ sudo systemctl enable rsyslog.service

Generate Mitigation Statement:

Checks: C-32968r567643_chk

Verify file systems that contain user home directories are mounted with the "nosuid" option. Note: If a separate file system has not been created for the user home directories (user home directories are mounted under "/"), this is automatically a finding as the "nosuid" option cannot be used on the "/" system. Find the file system(s) that contain the user home directories with the following command: $ sudo awk -F: '($3>=1000)&&($7 !~ /nologin/){print $1,$3,$6}' /etc/passwd smithj:1001: /home/smithj robinst:1002: /home/robinst Check the file systems that are mounted at boot time with the following command: $ sudo more /etc/fstab UUID=a411dc99-f2a1-4c87-9e05-184977be8539 /home xfs rw,relatime,discard,data=ordered,nosuid,nodev,noexec 0 0 If a file system found in "/etc/fstab" refers to the user home directory file system and it does not have the "nosuid" option set, this is a finding.

Fix: F-32943r567644_fix

Configure the "/etc/fstab" to use the "nosuid" option on file systems that contain user home directories for interactive users.

Generate Mitigation Statement:

Checks: C-32969r743958_chk

For systems that use UEFI, this is Not Applicable. Verify the /boot directory is mounted with the "nosuid" option with the following command: $ sudo mount | grep '\s/boot\s' /dev/sda1 on /boot type xfs (rw,nosuid,relatime,seclabe,attr2,inode64,noquota) If the /boot file system does not have the "nosuid" option set, this is a finding.

Fix: F-32944r567647_fix

Configure the "/etc/fstab" to use the "nosuid" option on the /boot directory.

Generate Mitigation Statement:

Checks: C-32970r567649_chk

Verify all non-root local partitions are mounted with the "nodev" option with the following command: $ sudo mount | grep '^/dev\S* on /\S' | grep --invert-match 'nodev' If any output is produced, this is a finding.

Fix: F-32945r567650_fix

Configure the "/etc/fstab" to use the "nodev" option on all non-root local partitions.

Generate Mitigation Statement:

Checks: C-32971r567652_chk

Verify file systems that contain user home directories are mounted with the "noexec" option. Note: If a separate file system has not been created for the user home directories (user home directories are mounted under "/"), this is automatically a finding as the "noexec" option cannot be used on the "/" system. Find the file system(s) that contain the user home directories with the following command: $ sudo awk -F: '($3>=1000)&&($7 !~ /nologin/){print $1,$3,$6}' /etc/passwd smithj:1001: /home/smithj robinst:1002: /home/robinst Check the file systems that are mounted at boot time with the following command: $ sudo more /etc/fstab UUID=a411dc99-f2a1-4c87-9e05-184977be8539 /home ext4 rw,relatime,discard,data=ordered,nosuid,nodev,noexec 0 2 If a file system found in "/etc/fstab" refers to the user home directory file system and it does not have the "noexec" option set, this is a finding.

Fix: F-32946r567653_fix

Configure the "/etc/fstab" to use the "noexec" option on file systems that contain user home directories for interactive users.

Generate Mitigation Statement:

Checks: C-32972r567655_chk

Verify file systems that are used for removable media are mounted with the "nodev" option with the following command: $ sudo more /etc/fstab UUID=2bc871e4-e2a3-4f29-9ece-3be60c835222 /mnt/usbflash vfat noauto,owner,ro,nosuid,nodev,noexec 0 0 If a file system found in "/etc/fstab" refers to removable media and it does not have the "nodev" option set, this is a finding.

Fix: F-32947r567656_fix

Configure the "/etc/fstab" to use the "nodev" option on file systems that are associated with removable media.

Generate Mitigation Statement:

Checks: C-32973r567658_chk

Verify file systems that are used for removable media are mounted with the "noexec" option with the following command: $ sudo more /etc/fstab UUID=2bc871e4-e2a3-4f29-9ece-3be60c835222 /mnt/usbflash vfat noauto,owner,ro,nosuid,nodev,noexec 0 0 If a file system found in "/etc/fstab" refers to removable media and it does not have the "noexec" option set, this is a finding.

Fix: F-32948r567659_fix

Configure the "/etc/fstab" to use the "noexec" option on file systems that are associated with removable media.

Generate Mitigation Statement:

Checks: C-32974r567661_chk

Verify file systems that are used for removable media are mounted with the "nosuid" option with the following command: $ sudo more /etc/fstab UUID=2bc871e4-e2a3-4f29-9ece-3be60c835222 /mnt/usbflash vfat noauto,owner,ro,nosuid,nodev,noexec 0 0 If a file system found in "/etc/fstab" refers to removable media and it does not have the "nosuid" option set, this is a finding.

Fix: F-32949r567662_fix

Configure the "/etc/fstab" to use the "nosuid" option on file systems that are associated with removable media.

Generate Mitigation Statement:

Checks: C-32975r567664_chk

Verify that file systems being imported via NFS are mounted with the "noexec" option with the following command: $ sudo grep nfs /etc/fstab | grep noexec UUID=e06097bb-cfcd-437b-9e4d-a691f5662a7d /store nfs rw,nosuid,nodev,noexec 0 0 If a file system found in "/etc/fstab" refers to NFS and it does not have the "noexec" option set, this is a finding.

Fix: F-32950r567665_fix

Configure the "/etc/fstab" to use the "noexec" option on file systems that are being imported via NFS.

Generate Mitigation Statement:

Checks: C-32976r567667_chk

Verify file systems that are being NFS-imported are mounted with the "nodev" option with the following command: $ sudo grep nfs /etc/fstab | grep nodev UUID=e06097bb-cfcd-437b-9e4d-a691f5662a7d /store nfs rw,nosuid,nodev,noexec 0 0 If a file system found in "/etc/fstab" refers to NFS and it does not have the "nodev" option set, this is a finding.

Fix: F-32951r567668_fix

Configure the "/etc/fstab" to use the "nodev" option on file systems that are being imported via NFS.

Generate Mitigation Statement:

Checks: C-32977r567670_chk

Verify that file systems being imported via NFS are mounted with the "nosuid" option with the following command: $ sudo grep nfs /etc/fstab | grep nosuid UUID=e06097bb-cfcd-437b-9e4d-a691f5662a7d /store nfs rw,nosuid,nodev,noexec 0 0 If a file system found in "/etc/fstab" refers to NFS and it does not have the "nosuid" option set, this is a finding.

Fix: F-32952r567671_fix

Configure the "/etc/fstab" to use the "nosuid" option on file systems that are being imported via NFS.

Generate Mitigation Statement:

Checks: C-32978r567673_chk

Verify that local initialization files do not execute world-writable programs. Check the system for world-writable files. The following command will discover and print world-writable files. Run it once for each local partition [PART]: $ sudo find [PART] -xdev -type f -perm -0002 -print For all files listed, check for their presence in the local initialization files with the following commands: Note: The example will be for a system that is configured to create user home directories in the "/home" directory. $ sudo grep <file> /home/*/.* If any local initialization files are found to reference world-writable files, this is a finding.

Fix: F-32953r567674_fix

Set the mode on files being executed by the local initialization files with the following command: $ sudo chmod 0755 <file>

Generate Mitigation Statement:

Checks: C-32979r567676_chk

Verify that kernel core dumps are disabled unless needed with the following command: $ sudo systemctl status kdump.service kdump.service - Crash recovery kernel arming Loaded: loaded (/usr/lib/systemd/system/kdump.service; enabled; vendor preset: enabled) Active: active (exited) since Mon 2020-05-04 16:08:09 EDT; 3min ago Main PID: 1130 (code=exited, status=0/SUCCESS) If the "kdump" service is active, ask the System Administrator if the use of the service is required and documented with the Information System Security Officer (ISSO). If the service is active and is not documented, this is a finding.

Fix: F-32954r567677_fix

If kernel core dumps are not required, disable the "kdump" service with the following command: # systemctl disable kdump.service If kernel core dumps are required, document the need with the ISSO.

Generate Mitigation Statement:

Checks: C-32980r833304_chk

Verify RHEL 8 disables storing core dumps with the following commands: $ sudo sysctl kernel.core_pattern kernel.core_pattern = |/bin/false If the returned line does not have a value of "|/bin/false", or a line is not returned and the need for core dumps is not documented with the Information System Security Officer (ISSO) as an operational requirement, this is a finding. Check that the configuration files are present to enable this kernel parameter. $ sudo grep -r kernel.core_pattern /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf /lib/sysctl.d/*.conf /etc/sysctl.conf /etc/sysctl.d/*.conf /etc/sysctl.d/99-sysctl.conf:kernel.core_pattern = |/bin/false If "kernel.core_pattern" is not set to "|/bin/false", is missing or commented out, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-32955r858768_fix

Configure RHEL 8 to disable storing core dumps. Add or edit the following line in a system configuration file, in the "/etc/sysctl.d/" directory: kernel.core_pattern = |/bin/false Remove any configurations that conflict with the above from the following locations: /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf /lib/sysctl.d/*.conf /etc/sysctl.conf /etc/sysctl.d/*.conf The system configuration files need to be reloaded for the changes to take effect. To reload the contents of the files, run the following command: $ sudo sysctl --system

Generate Mitigation Statement:

Checks: C-32981r833306_chk

Verify RHEL 8 is not configured to acquire, save, or process core dumps with the following command: $ sudo systemctl status systemd-coredump.socket systemd-coredump.socket Loaded: masked (Reason: Unit systemd-coredump.socket is masked.) Active: inactive (dead) If the "systemd-coredump.socket" is loaded and not masked and the need for core dumps is not documented with the Information System Security Officer (ISSO) as an operational requirement, this is a finding.

Fix: F-32956r833307_fix

Configure the system to disable the systemd-coredump.socket with the following commands: $ sudo systemctl disable --now systemd-coredump.socket $ sudo systemctl mask systemd-coredump.socket Created symlink /etc/systemd/system/systemd-coredump.socket -> /dev/null Reload the daemon for this change to take effect. $ sudo systemctl daemon-reload

Generate Mitigation Statement:

Checks: C-32982r567685_chk

Verify the operating system disables core dumps for all users by issuing the following command: $ sudo grep -r -s '^[^#].*core' /etc/security/limits.conf /etc/security/limits.d/*.conf * hard core 0 This can be set as a global domain (with the * wildcard) but may be set differently for multiple domains. If the "core" item is missing, commented out, or the value is anything other than "0" and the need for core dumps is not documented with the Information System Security Officer (ISSO) as an operational requirement for all domains that have the "core" item assigned, this is a finding.

Fix: F-32957r619861_fix

Configure the operating system to disable core dumps for all users. Add the following line to the top of the /etc/security/limits.conf or in a ".conf" file defined in /etc/security/limits.d/: * hard core 0

Generate Mitigation Statement:

Checks: C-32983r567688_chk

Verify the operating system disables storing core dumps for all users by issuing the following command: $ sudo grep -i storage /etc/systemd/coredump.conf Storage=none If the "Storage" item is missing, commented out, or the value is anything other than "none" and the need for core dumps is not documented with the Information System Security Officer (ISSO) as an operational requirement for all domains that have the "core" item assigned, this is a finding.

Fix: F-32958r567689_fix

Configure the operating system to disable storing core dumps for all users. Add or modify the following line in /etc/systemd/coredump.conf: Storage=none

Generate Mitigation Statement:

Checks: C-32984r567691_chk

Verify the operating system disables core dump backtraces by issuing the following command: $ sudo grep -i ProcessSizeMax /etc/systemd/coredump.conf ProcessSizeMax=0 If the "ProcessSizeMax" item is missing, commented out, or the value is anything other than "0" and the need for core dumps is not documented with the Information System Security Officer (ISSO) as an operational requirement for all domains that have the "core" item assigned, this is a finding.

Fix: F-32959r567692_fix

Configure the operating system to disable core dump backtraces. Add or modify the following line in /etc/systemd/coredump.conf: ProcessSizeMax=0

Generate Mitigation Statement:

Checks: C-32985r567694_chk

Determine whether the system is using local or DNS name resolution with the following command: $ sudo grep hosts /etc/nsswitch.conf hosts: files dns If the DNS entry is missing from the host's line in the "/etc/nsswitch.conf" file, the "/etc/resolv.conf" file must be empty. Verify the "/etc/resolv.conf" file is empty with the following command: $ sudo ls -al /etc/resolv.conf -rw-r--r-- 1 root root 0 Aug 19 08:31 resolv.conf If local host authentication is being used and the "/etc/resolv.conf" file is not empty, this is a finding. If the DNS entry is found on the host's line of the "/etc/nsswitch.conf" file, verify the operating system is configured to use two or more name servers for DNS resolution. Determine the name servers used by the system with the following command: $ sudo grep nameserver /etc/resolv.conf nameserver 192.168.1.2 nameserver 192.168.1.3 If less than two lines are returned that are not commented out, this is a finding.

Fix: F-32960r567695_fix

Configure the operating system to use two or more name servers for DNS resolution. By default, "NetworkManager" on RHEL 8 dynamically updates the /etc/resolv.conf file with the DNS settings from active "NetworkManager" connection profiles. However, this feature can be disabled to allow manual configurations. If manually configuring DNS, edit the "/etc/resolv.conf" file to uncomment or add the two or more "nameserver" option lines with the IP address of local authoritative name servers. If local host resolution is being performed, the "/etc/resolv.conf" file must be empty. An empty "/etc/resolv.conf" file can be created as follows: $ sudo echo -n > /etc/resolv.conf

Generate Mitigation Statement:

Checks: C-32986r792895_chk

Verify that all local interactive user initialization file executable search path statements do not contain statements that will reference a working directory other than user home directories with the following commands: $ sudo grep -i path= /home/*/.* /home/[localinteractiveuser]/.bash_profile:PATH=$PATH:$HOME/.local/bin:$HOME/bin If any local interactive user initialization files have executable search path statements that include directories outside of their home directory and is not documented with the ISSO as an operational requirement, this is a finding.

Fix: F-32961r567698_fix

Edit the local interactive user initialization files to change any PATH variable statements that reference directories other than their home directory. If a local interactive user requires path variables to reference a directory owned by the application, it must be documented with the ISSO.

Generate Mitigation Statement:

Checks: C-32987r567700_chk

The following command will discover and print world-writable directories that are not owned by a system account, given the assumption that only system accounts have a uid lower than 1000. Run it once for each local partition [PART]: $ sudo find [PART] -xdev -type d -perm -0002 -uid +999 -print If there is output, this is a finding.

Fix: F-32962r567701_fix

All directories in local partitions which are world-writable should be owned by root or another system account. If any world-writable directories are not owned by a system account, this should be investigated. Following this, the files should be deleted or assigned to an appropriate group.

Generate Mitigation Statement:

Checks: C-32988r567703_chk

The following command will discover and print world-writable directories that are not group-owned by a system account, given the assumption that only system accounts have a gid lower than 1000. Run it once for each local partition [PART]: $ sudo find [PART] -xdev -type d -perm -0002 -gid +999 -print If there is output, this is a finding.

Fix: F-32963r567704_fix

All directories in local partitions which are world-writable must be group-owned by root or another system account. If any world-writable directories are not group-owned by a system account, this must be investigated. Following this, the directories must be deleted or assigned to an appropriate group.

Generate Mitigation Statement:

Checks: C-32989r567706_chk

Verify local interactive users on RHEL 8 have a home directory assigned with the following command: $ sudo pwck -r user 'lp': directory '/var/spool/lpd' does not exist user 'news': directory '/var/spool/news' does not exist user 'uucp': directory '/var/spool/uucp' does not exist user 'www-data': directory '/var/www' does not exist Ask the System Administrator (SA) if any users found without home directories are local interactive users. If the SA is unable to provide a response, check for users with a User Identifier (UID) of 1000 or greater with the following command: $ sudo awk -F: '($3&gt;=1000)&amp;&amp;($7 !~ /nologin/){print $1, $3, $6}' /etc/passwd If any interactive users do not have a home directory assigned, this is a finding.

Fix: F-32964r567707_fix

Assign home directories to all local interactive users on RHEL 8 that currently do not have a home directory assigned.

Generate Mitigation Statement:

Checks: C-32990r567709_chk

Verify the assigned home directory of all local interactive users has a mode of "0750" or less permissive with the following command: Note: This may miss interactive users that have been assigned a privileged User Identifier (UID). Evidence of interactive use may be obtained from a number of log files containing system logon information. $ sudo ls -ld $(awk -F: '($3&gt;=1000)&amp;&amp;($7 !~ /nologin/){print $6}' /etc/passwd) drwxr-x--- 2 smithj admin 4096 Jun 5 12:41 smithj If home directories referenced in "/etc/passwd" do not have a mode of "0750" or less permissive, this is a finding.

Fix: F-32965r567710_fix

Change the mode of interactive user’s home directories to "0750". To change the mode of a local interactive user’s home directory, use the following command: Note: The example will be for the user "smithj". $ sudo chmod 0750 /home/smithj

Generate Mitigation Statement:

Checks: C-32991r880715_chk

Verify the assigned home directory of all local interactive users is group-owned by that user’s primary GID with the following command: Note: This may miss local interactive users that have been assigned a privileged UID. Evidence of interactive use may be obtained from a number of log files containing system logon information. The returned directory "/home/smithj" is used as an example. $ sudo ls -ld $(awk -F: '($3&gt;=1000)&amp;&amp;($7 !~ /nologin/){print $6}' /etc/passwd) drwxr-x--- 2 smithj admin 4096 Jun 5 12:41 smithj Check the user's primary group with the following command: $ sudo grep $(grep smithj /etc/passwd | awk -F: '{print $4}') /etc/group admin:x:250:smithj,jonesj,jacksons If the user home directory referenced in "/etc/passwd" is not group-owned by that user’s primary GID, this is a finding.

Fix: F-32966r880716_fix

Change the group owner of a local interactive user’s home directory to the group found in "/etc/passwd". To change the group owner of a local interactive user’s home directory, use the following command: Note: The example will be for the user "smithj", who has a home directory of "/home/smithj", and has a primary group of users. $ sudo chgrp users /home/smithj

Generate Mitigation Statement:

Checks: C-32992r567715_chk

Verify the assigned home directory of all local interactive users on RHEL 8 exists with the following command: $ sudo ls -ld $(awk -F: '($3&gt;=1000)&amp;&amp;($7 !~ /nologin/){print $6}' /etc/passwd) drwxr-xr-x 2 smithj admin 4096 Jun 5 12:41 smithj Note: This may miss interactive users that have been assigned a privileged User ID (UID). Evidence of interactive use may be obtained from a number of log files containing system logon information. Check that all referenced home directories exist with the following command: $ sudo pwck -r user 'smithj': directory '/home/smithj' does not exist If any home directories referenced in "/etc/passwd" are returned as not defined, this is a finding.

Fix: F-32967r567716_fix

Create home directories to all local interactive users that currently do not have a home directory assigned. Use the following commands to create the user home directory assigned in "/etc/ passwd": Note: The example will be for the user smithj, who has a home directory of "/home/smithj", a UID of "smithj", and a Group Identifier (GID) of "users assigned" in "/etc/passwd". $ sudo mkdir /home/smithj $ sudo chown smithj /home/smithj $ sudo chgrp users /home/smithj $ sudo chmod 0750 /home/smithj

Generate Mitigation Statement:

Checks: C-32993r567718_chk

Verify all local interactive users on RHEL 8 are assigned a home directory upon creation with the following command: $ sudo grep -i create_home /etc/login.defs CREATE_HOME yes If the value for "CREATE_HOME" parameter is not set to "yes", the line is missing, or the line is commented out, this is a finding.

Fix: F-32968r567719_fix

Configure RHEL 8 to assign home directories to all new local interactive users by setting the "CREATE_HOME" parameter in "/etc/login.defs" to "yes" as follows. CREATE_HOME yes

Generate Mitigation Statement:

Checks: C-32994r917877_chk

Verify that all local initialization files have a mode of "0740" or less permissive with the following command: Note: The example will be for the "smithj" user, who has a home directory of "/home/smithj". $ sudo ls -al /home/smithj/.[^.]* | more -rw-------. 1 smithj users 2984 Apr 27 19:02 .bash_history -rw-r--r--. 1 smithj users 18 Aug 21 2019 .bash_logout -rw-r--r--. 1 smithj users 193 Aug 21 2019 .bash_profile If any local initialization files have a mode more permissive than "0740", this is a finding.

Fix: F-32969r917878_fix

Set the mode of the local initialization files to "0740" with the following command: Note: The example will be for the smithj user, who has a home directory of "/home/smithj". $ sudo chmod 0740 /home/smithj/.<INIT_FILE>

Generate Mitigation Statement:

Checks: C-32995r567724_chk

Verify all local files and directories on RHEL 8 have a valid owner with the following command: Note: The value after -fstype must be replaced with the filesystem type. XFS is used as an example. $ sudo find / -fstype xfs -nouser If any files on the system do not have an assigned owner, this is a finding. Note: Command may produce error messages from the /proc and /sys directories.

Fix: F-32970r567725_fix

Either remove all files and directories from the system that do not have a valid user, or assign a valid user to all unowned files and directories on RHEL 8 with the "chown" command: $ sudo chown <user> <file>

Generate Mitigation Statement:

Checks: C-32996r567727_chk

Verify all local files and directories on RHEL 8 have a valid group with the following command: Note: The value after -fstype must be replaced with the filesystem type. XFS is used as an example. $ sudo find / -fstype xfs -nogroup If any files on the system do not have an assigned group, this is a finding. Note: Command may produce error messages from the /proc and /sys directories.

Fix: F-32971r567728_fix

Either remove all files and directories from RHEL 8 that do not have a valid group, or assign a valid group to all files and directories on the system with the "chgrp" command: $ sudo chgrp <group> <file>

Generate Mitigation Statement:

Checks: C-32997r902721_chk

Verify that a separate file system has been created for non-privileged local interactive user home directories. Check the home directory assignment for all non-privileged users, users with a User Identifier (UID) greater than 1000, on the system with the following command: $ sudo awk -F: '($3&gt;=1000)&amp;&amp;($7 !~ /nologin/){print $1,$3,$6}' /etc/passwd doej 1001 /home/doej publicj 1002 /home/publicj smithj 1003 /home/smithj The output of the command will give the directory/partition that contains the home directories for the non-privileged users on the system (in this example, "/home") and users’ shell. All accounts with a valid shell (such as /bin/bash) are considered interactive users. Check that a file system/partition has been created for the nonprivileged interactive users with the following command: Note: The partition of "/home" is used in the example. $ sudo grep /home /etc/fstab /dev/mapper/... /home xfs defaults,noexec,nosuid,nodev 0 0 If a separate entry for the file system/partition containing the nonprivileged interactive user home directories does not exist, this is a finding.

Fix: F-32972r902722_fix

Migrate the "/home" directory onto a separate file system.

Generate Mitigation Statement:

Checks: C-32999r858712_chk

Verify that unattended or automatic logon via ssh is disabled with the following command: $ sudo grep -ir PermitUserEnvironment /etc/ssh/sshd_config* PermitUserEnvironment no If "PermitUserEnvironment" is set to "yes", is missing completely, or is commented out, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-32974r567737_fix

Configure RHEL 8 to allow the SSH daemon to not allow unattended or automatic logon to the system. Add or edit the following line in the "/etc/ssh/sshd_config" file: PermitUserEnvironment no The SSH daemon must be restarted for the changes to take effect. To restart the SSH daemon, run the following command: $ sudo systemctl restart sshd.service

Generate Mitigation Statement:

Checks: C-33000r619865_chk

Verify that temporary accounts have been provisioned with an expiration date of 72 hours. For every existing temporary account, run the following command to obtain its account expiration information. $ sudo chage -l system_account_name Verify each of these accounts has an expiration date set within 72 hours. If any temporary accounts have no expiration date set or do not expire within 72 hours, this is a finding.

Fix: F-32975r567740_fix

If a temporary account must be created configure the system to terminate the account after a 72 hour time period with the following command to set an expiration date on it. Substitute "system_account_name" with the account to be created. $ sudo chage -E `date -d "+3 days" +%Y-%m-%d` system_account_name

Generate Mitigation Statement:

Checks: C-33001r567742_chk

Check that the system locks an account after three unsuccessful logon attempts with the following commands: Note: If the System Administrator demonstrates the use of an approved centralized account management method that locks an account after three unsuccessful logon attempts within a period of 15 minutes, this requirement is not applicable. Note: This check applies to RHEL versions 8.0 and 8.1, if the system is RHEL version 8.2 or newer, this check is not applicable. $ sudo grep pam_faillock.so /etc/pam.d/password-auth auth required pam_faillock.so preauth dir=/var/log/faillock silent audit deny=3 even_deny_root fail_interval=900 unlock_time=0 auth required pam_faillock.so authfail dir=/var/log/faillock unlock_time=0 account required pam_faillock.so If the "deny" option is not set to "3" or less (but not "0") on the "preauth" line with the "pam_faillock.so" module, or is missing from this line, this is a finding. If any line referencing the "pam_faillock.so" module is commented out, this is a finding. $ sudo grep pam_faillock.so /etc/pam.d/system-auth auth required pam_faillock.so preauth dir=/var/log/faillock silent audit deny=3 even_deny_root fail_interval=900 unlock_time=0 auth required pam_faillock.so authfail dir=/var/log/faillock unlock_time=0 account required pam_faillock.so If the "deny" option is not set to "3" or less (but not "0") on the "preauth" line with the "pam_faillock.so" module, or is missing from this line, this is a finding. If any line referencing the "pam_faillock.so" module is commented out, this is a finding.

Fix: F-32976r567743_fix

Configure the operating system to lock an account when three unsuccessful logon attempts occur. Add/Modify the appropriate sections of the "/etc/pam.d/system-auth" and "/etc/pam.d/password-auth" files to match the following lines: auth required pam_faillock.so preauth dir=/var/log/faillock silent audit deny=3 even_deny_root fail_interval=900 unlock_time=0 auth required pam_faillock.so authfail dir=/var/log/faillock unlock_time=0 account required pam_faillock.so The "sssd" service must be restarted for the changes to take effect. To restart the "sssd" service, run the following command: $ sudo systemctl restart sssd.service

Generate Mitigation Statement:

Checks: C-33002r743964_chk

Note: This check applies to RHEL versions 8.2 or newer, if the system is RHEL version 8.0 or 8.1, this check is not applicable. Verify the "/etc/security/faillock.conf" file is configured to lock an account after three unsuccessful logon attempts: $ sudo grep 'deny =' /etc/security/faillock.conf deny = 3 If the "deny" option is not set to "3" or less (but not "0"), is missing or commented out, this is a finding.

Fix: F-32977r743965_fix

Configure the operating system to lock an account when three unsuccessful logon attempts occur. Add/Modify the "/etc/security/faillock.conf" file to match the following line: deny = 3

Generate Mitigation Statement:

Checks: C-33003r567748_chk

Check that the system locks an account after three unsuccessful logon attempts within a period of 15 minutes with the following commands: Note: If the System Administrator demonstrates the use of an approved centralized account management method that locks an account after three unsuccessful logon attempts within a period of 15 minutes, this requirement is not applicable. Note: This check applies to RHEL versions 8.0 and 8.1, if the system is RHEL version 8.2 or newer, this check is not applicable. $ sudo grep pam_faillock.so /etc/pam.d/password-auth auth required pam_faillock.so preauth dir=/var/log/faillock silent audit deny=3 even_deny_root fail_interval=900 unlock_time=0 auth required pam_faillock.so authfail dir=/var/log/faillock unlock_time=0 account required pam_faillock.so If the "fail_interval" option is not set to "900" or less (but not "0") on the "preauth" lines with the "pam_faillock.so" module, or is missing from this line, this is a finding. $ sudo grep pam_faillock.so /etc/pam.d/system-auth auth required pam_faillock.so preauth dir=/var/log/faillock silent audit deny=3 even_deny_root fail_interval=900 unlock_time=0 auth required pam_faillock.so authfail dir=/var/log/faillock unlock_time=0 account required pam_faillock.so If the "fail_interval" option is not set to "900" or less (but not "0") on the "preauth" lines with the "pam_faillock.so" module, or is missing from this line, this is a finding.

Fix: F-32978r567749_fix

Configure the operating system to lock an account when three unsuccessful logon attempts occur in 15 minutes. Add/Modify the appropriate sections of the "/etc/pam.d/system-auth" and "/etc/pam.d/password-auth" files to match the following lines: auth required pam_faillock.so preauth dir=/var/log/faillock silent audit deny=3 even_deny_root fail_interval=900 unlock_time=0 auth required pam_faillock.so authfail dir=/var/log/faillock unlock_time=0 account required pam_faillock.so The "sssd" service must be restarted for the changes to take effect. To restart the "sssd" service, run the following command: $ sudo systemctl restart sssd.service

Generate Mitigation Statement:

Checks: C-33004r743967_chk

Note: This check applies to RHEL versions 8.2 or newer, if the system is RHEL version 8.0 or 8.1, this check is not applicable. Verify the "/etc/security/faillock.conf" file is configured to lock an account after three unsuccessful logon attempts within 15 minutes: $ sudo grep 'fail_interval =' /etc/security/faillock.conf fail_interval = 900 If the "fail_interval" option is not set to "900" or more, is missing or commented out, this is a finding.

Fix: F-32979r743968_fix

Configure the operating system to lock an account when three unsuccessful logon attempts occur in 15 minutes. Add/Modify the "/etc/security/faillock.conf" file to match the following line: fail_interval = 900

Generate Mitigation Statement:

Checks: C-33005r567754_chk

Check that the system locks an account after three unsuccessful logon attempts within a period of 15 minutes until released by an administrator with the following commands: Note: If the System Administrator demonstrates the use of an approved centralized account management method that locks an account after three unsuccessful logon attempts within a period of 15 minutes, this requirement is not applicable. Note: This check applies to RHEL versions 8.0 and 8.1, if the system is RHEL version 8.2 or newer, this check is not applicable. $ sudo grep pam_faillock.so /etc/pam.d/password-auth auth required pam_faillock.so preauth dir=/var/log/faillock silent audit deny=3 even_deny_root fail_interval=900 unlock_time=0 auth required pam_faillock.so authfail dir=/var/log/faillock unlock_time=0 account required pam_faillock.so If the "unlock_time" option is not set to "0" on the "preauth" and "authfail" lines with the "pam_faillock.so" module, or is missing from these lines, this is a finding. $ sudo grep pam_faillock.so /etc/pam.d/system-auth auth required pam_faillock.so preauth dir=/var/log/faillock silent audit deny=3 even_deny_root fail_interval=900 unlock_time=0 auth required pam_faillock.so authfail dir=/var/log/faillock unlock_time=0 account required pam_faillock.so If the "unlock_time" option is not set to "0" on the "preauth" and "authfail" lines with the "pam_faillock.so" module, or is missing from these lines, this is a finding.

Fix: F-32980r567755_fix

Configure the operating system to lock an account until released by an administrator when three unsuccessful logon attempts occur in 15 minutes. Add/Modify the appropriate sections of the "/etc/pam.d/system-auth" and "/etc/pam.d/password-auth" files to match the following lines: auth required pam_faillock.so preauth dir=/var/log/faillock silent audit deny=3 even_deny_root fail_interval=900 unlock_time=0 auth required pam_faillock.so authfail dir=/var/log/faillock unlock_time=0 account required pam_faillock.so The "sssd" service must be restarted for the changes to take effect. To restart the "sssd" service, run the following command: $ sudo systemctl restart sssd.service

Generate Mitigation Statement:

Checks: C-33006r743970_chk

Note: This check applies to RHEL versions 8.2 or newer, if the system is RHEL version 8.0 or 8.1, this check is not applicable. Verify the "/etc/security/faillock.conf" file is configured to lock an account until released by an administrator after three unsuccessful logon attempts: $ sudo grep 'unlock_time =' /etc/security/faillock.conf unlock_time = 0 If the "unlock_time" option is not set to "0", is missing or commented out, this is a finding.

Fix: F-32981r743971_fix

Configure the operating system to lock an account until released by an administrator when three unsuccessful logon attempts occur in 15 minutes. Add/Modify the "/etc/security/faillock.conf" file to match the following line: unlock_time = 0

Generate Mitigation Statement:

Checks: C-33007r567760_chk

Check that the faillock directory contents persists after a reboot with the following commands: Note: If the System Administrator demonstrates the use of an approved centralized account management method that locks an account after three unsuccessful logon attempts within a period of 15 minutes, this requirement is not applicable. Note: This check applies to RHEL versions 8.0 and 8.1, if the system is RHEL version 8.2 or newer, this check is not applicable. $ sudo grep pam_faillock.so /etc/pam.d/password-auth auth required pam_faillock.so preauth dir=/var/log/faillock silent audit deny=3 even_deny_root fail_interval=900 unlock_time=0 auth required pam_faillock.so authfail dir=/var/log/faillock unlock_time=0 account required pam_faillock.so If the "dir" option is not set to a non-default documented tally log directory on the "preauth" and "authfail" lines with the "pam_faillock.so" module, or is missing from these lines, this is a finding. $ sudo grep pam_faillock.so /etc/pam.d/system-auth auth required pam_faillock.so preauth dir=/var/log/faillock silent audit deny=3 even_deny_root fail_interval=900 unlock_time=0 auth required pam_faillock.so authfail dir=/var/log/faillock unlock_time=0 account required pam_faillock.so If the "dir" option is not set to a non-default documented tally log directory on the "preauth" and "authfail" lines with the "pam_faillock.so" module, or is missing from these lines, this is a finding.

Fix: F-32982r567761_fix

Configure the operating system maintain the contents of the faillock directory after a reboot. Add/Modify the appropriate sections of the "/etc/pam.d/system-auth" and "/etc/pam.d/password-auth" files to match the following lines: Note: Using the default faillock directory of /var/run/faillock will result in the contents being cleared in the event of a reboot. auth required pam_faillock.so preauth dir=/var/log/faillock silent audit deny=3 even_deny_root fail_interval=900 unlock_time=0 auth required pam_faillock.so authfail dir=/var/log/faillock unlock_time=0 account required pam_faillock.so The "sssd" service must be restarted for the changes to take effect. To restart the "sssd" service, run the following command: $ sudo systemctl restart sssd.service

Generate Mitigation Statement:

Checks: C-33008r743973_chk

Note: This check applies to RHEL versions 8.2 or newer. If the system is RHEL version 8.0 or 8.1, this check is not applicable. Verify the "/etc/security/faillock.conf" file is configured use a non-default faillock directory to ensure contents persist after reboot: $ sudo grep 'dir =' /etc/security/faillock.conf dir = /var/log/faillock If the "dir" option is not set to a non-default documented tally log directory, is missing or commented out, this is a finding.

Fix: F-32983r743974_fix

Configure the operating system maintain the contents of the faillock directory after a reboot. Add/Modify the "/etc/security/faillock.conf" file to match the following line: dir = /var/log/faillock

Generate Mitigation Statement:

Checks: C-33009r567766_chk

Check that the system prevents informative messages from being presented to the user pertaining to logon information with the following commands: Note: If the System Administrator demonstrates the use of an approved centralized account management method that locks an account after three unsuccessful logon attempts within a period of 15 minutes, this requirement is not applicable. Note: This check applies to RHEL versions 8.0 and 8.1, if the system is RHEL version 8.2 or newer, this check is not applicable. $ sudo grep pam_faillock.so /etc/pam.d/password-auth auth required pam_faillock.so preauth dir=/var/log/faillock silent audit deny=3 even_deny_root fail_interval=900 unlock_time=0 auth required pam_faillock.so authfail dir=/var/log/faillock unlock_time=0 account required pam_faillock.so If the "silent" option is missing from the "preauth" line with the "pam_faillock.so" module, this is a finding. $ sudo grep pam_faillock.so /etc/pam.d/system-auth auth required pam_faillock.so preauth dir=/var/log/faillock silent audit deny=3 even_deny_root fail_interval=900 unlock_time=0 auth required pam_faillock.so authfail dir=/var/log/faillock unlock_time=0 account required pam_faillock.so If the "silent" option is missing from the "preauth" line with the "pam_faillock.so" module, this is a finding.

Fix: F-32984r567767_fix

Configure the operating system to prevent informative messages from being presented at logon attempts. Add/Modify the appropriate sections of the "/etc/pam.d/system-auth" and "/etc/pam.d/password-auth" files to match the following lines: auth required pam_faillock.so preauth dir=/var/log/faillock silent audit deny=3 even_deny_root fail_interval=900 unlock_time=0 auth required pam_faillock.so authfail dir=/var/log/faillock unlock_time=0 account required pam_faillock.so The "sssd" service must be restarted for the changes to take effect. To restart the "sssd" service, run the following command: $ sudo systemctl restart sssd.service

Generate Mitigation Statement:

Checks: C-33010r743976_chk

Note: This check applies to RHEL versions 8.2 or newer, if the system is RHEL version 8.0 or 8.1, this check is not applicable. Verify the "/etc/security/faillock.conf" file is configured to prevent informative messages from being presented at logon attempts: $ sudo grep silent /etc/security/faillock.conf silent If the "silent" option is not set, is missing or commented out, this is a finding.

Fix: F-32985r743977_fix

Configure the operating system to prevent informative messages from being presented at logon attempts. Add/Modify the "/etc/security/faillock.conf" file to match the following line: silent

Generate Mitigation Statement:

Checks: C-33011r646871_chk

Check that the system logs user name information when unsuccessful logon attempts occur with the following commands: If the system is RHEL version 8.2 or newer, this check is not applicable. Note: If the System Administrator demonstrates the use of an approved centralized account management method that locks an account after three unsuccessful logon attempts within a period of 15 minutes, this requirement is not applicable. $ sudo grep pam_faillock.so /etc/pam.d/password-auth auth required pam_faillock.so preauth dir=/var/log/faillock silent audit deny=3 even_deny_root fail_interval=900 unlock_time=0 auth required pam_faillock.so authfail dir=/var/log/faillock unlock_time=0 account required pam_faillock.so If the "audit" option is missing from the "preauth" line with the "pam_faillock.so" module, this is a finding. $ sudo grep pam_faillock.so /etc/pam.d/system-auth auth required pam_faillock.so preauth dir=/var/log/faillock silent audit deny=3 even_deny_root fail_interval=900 unlock_time=0 auth required pam_faillock.so authfail dir=/var/log/faillock unlock_time=0 account required pam_faillock.so If the "audit" option is missing from the "preauth" line with the "pam_faillock.so" module, this is a finding.

Fix: F-32986r567773_fix

Configure the operating system to log user name information when unsuccessful logon attempts occur. Add/Modify the appropriate sections of the "/etc/pam.d/system-auth" and "/etc/pam.d/password-auth" files to match the following lines: auth required pam_faillock.so preauth dir=/var/log/faillock silent audit deny=3 even_deny_root fail_interval=900 unlock_time=0 auth required pam_faillock.so authfail dir=/var/log/faillock unlock_time=0 account required pam_faillock.so The "sssd" service must be restarted for the changes to take effect. To restart the "sssd" service, run the following command: $ sudo systemctl restart sssd.service

Generate Mitigation Statement:

Checks: C-33012r743979_chk

Note: This check applies to RHEL versions 8.2 or newer, if the system is RHEL version 8.0 or 8.1, this check is not applicable. Verify the "/etc/security/faillock.conf" file is configured to log user name information when unsuccessful logon attempts occur: $ sudo grep audit /etc/security/faillock.conf audit If the "audit" option is not set, is missing or commented out, this is a finding.

Fix: F-32987r743980_fix

Configure the operating system to log user name information when unsuccessful logon attempts occur. Add/Modify the "/etc/security/faillock.conf" file to match the following line: audit

Generate Mitigation Statement:

Checks: C-33013r646873_chk

Check that the system includes the root account when locking an account after three unsuccessful logon attempts within a period of 15 minutes with the following commands: If the system is RHEL version 8.2 or newer, this check is not applicable. Note: If the System Administrator demonstrates the use of an approved centralized account management method that locks an account after three unsuccessful logon attempts within a period of 15 minutes, this requirement is not applicable. $ sudo grep pam_faillock.so /etc/pam.d/password-auth auth required pam_faillock.so preauth dir=/var/log/faillock silent audit deny=3 even_deny_root fail_interval=900 unlock_time=0 auth required pam_faillock.so authfail dir=/var/log/faillock unlock_time=0 account required pam_faillock.so If the "even_deny_root" option is missing from the "preauth" line with the "pam_faillock.so" module, this is a finding. $ sudo grep pam_faillock.so /etc/pam.d/system-auth auth required pam_faillock.so preauth dir=/var/log/faillock silent audit deny=3 even_deny_root fail_interval=900 unlock_time=0 auth required pam_faillock.so authfail dir=/var/log/faillock unlock_time=0 account required pam_faillock.so If the "even_deny_root" option is missing from the "preauth" line with the "pam_faillock.so" module, this is a finding.

Fix: F-32988r567779_fix

Configure the operating system to include root when locking an account after three unsuccessful logon attempts occur in 15 minutes. Add/Modify the appropriate sections of the "/etc/pam.d/system-auth" and "/etc/pam.d/password-auth" files to match the following lines: auth required pam_faillock.so preauth dir=/var/log/faillock silent audit deny=3 even_deny_root fail_interval=900 unlock_time=0 auth required pam_faillock.so authfail dir=/var/log/faillock unlock_time=0 account required pam_faillock.so The "sssd" service must be restarted for the changes to take effect. To restart the "sssd" service, run the following command: $ sudo systemctl restart sssd.service

Generate Mitigation Statement:

Checks: C-33014r743982_chk

Note: This check applies to RHEL versions 8.2 or newer, if the system is RHEL version 8.0 or 8.1, this check is not applicable. Verify the "/etc/security/faillock.conf" file is configured to log user name information when unsuccessful logon attempts occur: $ sudo grep even_deny_root /etc/security/faillock.conf even_deny_root If the "even_deny_root" option is not set, is missing or commented out, this is a finding.

Fix: F-32989r743983_fix

Configure the operating system to include root when locking an account after three unsuccessful logon attempts occur in 15 minutes. Add/Modify the "/etc/security/faillock.conf" file to match the following line: even_deny_root

Generate Mitigation Statement:

Checks: C-33016r567787_chk

Verify the operating system enables a user's session lock until that user re-establishes access using established identification and authentication procedures with the following command: $ sudo gsettings get org.gnome.desktop.screensaver lock-enabled true If the setting is "false", this is a finding. Note: This requirement assumes the use of the RHEL 8 default graphical user interface, Gnome Shell. If the system does not have any graphical user interface installed, this requirement is Not Applicable.

Fix: F-32991r567788_fix

Configure the operating system to enable a user's session lock until that user re-establishes access using established identification and authentication procedures. Create a database to contain the system-wide screensaver settings (if it does not already exist) with the following example: $ sudo vi /etc/dconf/db/local.d/00-screensaver Edit the "[org/gnome/desktop/screensaver]" section of the database file and add or update the following lines: # Set this to true to lock the screen when the screensaver activates lock-enabled=true Update the system databases: $ sudo dconf update

Generate Mitigation Statement:

Checks: C-33017r902724_chk

Verify the operating system enables the user to manually initiate a session lock with the following command: $ sudo grep -Ei 'lock-command|lock-session' /etc/tmux.conf set -g lock-command vlock bind X lock-session If the "lock-command" is not set and "lock-session" is not bound to a specific keyboard key in the global settings, this is a finding.

Fix: F-32992r880719_fix

Configure the operating system to enable a user to manually initiate a session lock via tmux. This configuration binds the uppercase letter "X" to manually initiate a session lock after the prefix key "Ctrl + b" has been sent. The complete key sequence is thus "Ctrl + b" then "Shift + x" to lock tmux. Create a global configuration file "/etc/tmux.conf" and add the following lines: set -g lock-command vlock bind X lock-session Reload tmux configuration to take effect. This can be performed in tmux while it is running: $ tmux source-file /etc/tmux.conf

Generate Mitigation Statement:

Checks: C-33018r880734_chk

Verify the operating system shell initialization file is configured to start each shell with the tmux terminal multiplexer with the following commands: Determine if tmux is currently running: $ sudo ps all | grep tmux | grep -v grep If the command does not produce output, this is a finding. Determine the location of the tmux script: $ sudo grep -r tmux /etc/bashrc /etc/profile.d /etc/profile.d/tmux.sh: case "$name" in (sshd|login) tmux ;; esac Review the tmux script by using the following example: $ sudo cat /etc/profile.d/tmux.sh if [ "$PS1" ]; then parent=$(ps -o ppid= -p $$) name=$(ps -o comm= -p $parent) case "$name" in (sshd|login) tmux ;; esac fi If "tmux" is not configured as the example above, is commented out, or is missing, this is a finding.

Fix: F-32993r880735_fix

Configure the operating system to initialize the tmux terminal multiplexer as each shell is called by adding the following lines to a custom.sh shell script in the /etc/profile.d/ directory: if [ "$PS1" ]; then parent=$(ps -o ppid= -p $$) name=$(ps -o comm= -p $parent) case "$name" in (sshd|login) tmux ;; esac fi This setting will take effect at next logon.

Generate Mitigation Statement:

Checks: C-33020r792897_chk

Verify the operating system enables a user's session lock until that user re-establishes access using established identification and authentication procedures with the following command: This requirement assumes the use of the RHEL 8 default graphical user interface, Gnome Shell. If the system does not have any graphical user interface installed, this requirement is Not Applicable. $ sudo grep -R removal-action /etc/dconf/db/* /etc/dconf/db/distro.d/20-authselect:removal-action='lock-screen' If the "removal-action='lock-screen'" setting is missing or commented out from the dconf database files, this is a finding.

Fix: F-32995r792898_fix

Configure the operating system to enable a user's session lock until that user re-establishes access using established identification and authentication procedures. Select/Create an authselect profile and incorporate the "with-smartcard-lock-on-removal" feature with the following example: $ sudo authselect select sssd with-smartcard with-smartcard-lock-on-removal Alternatively, the dconf settings can be edited in the /etc/dconf/db/* location. Edit or add the "[org/gnome/settings-daemon/peripherals/smartcard]" section of the database file and add or update the following lines: removal-action='lock-screen' Update the system databases: $ sudo dconf update

Generate Mitigation Statement:

Checks: C-33021r646875_chk

Verify the operating system initiates a session lock after a 15-minute period of inactivity for graphical user interfaces with the following commands: This requirement assumes the use of the RHEL 8 default graphical user interface, Gnome Shell. If the system does not have any graphical user interface installed, this requirement is Not Applicable. $ sudo gsettings get org.gnome.desktop.session idle-delay uint32 900 If "idle-delay" is set to "0" or a value greater than "900", this is a finding.

Fix: F-32996r567803_fix

Configure the operating system to initiate a screensaver after a 15-minute period of inactivity for graphical user interfaces. Create a database to contain the system-wide screensaver settings (if it does not already exist) with the following command: $ sudo touch /etc/dconf/db/local.d/00-screensaver Edit /etc/dconf/db/local.d/00-screensaver and add or update the following lines: [org/gnome/desktop/session] # Set the lock time out to 900 seconds before the session is considered idle idle-delay=uint32 900 Update the system databases: $ sudo dconf update

Generate Mitigation Statement:

Checks: C-33022r567805_chk

Verify the operating system initiates a session lock after 15 minutes of inactivity. Check the value of the system inactivity timeout with the following command: $ sudo grep -i lock-after-time /etc/tmux.conf set -g lock-after-time 900 If "lock-after-time" is not set to "900" or less in the global tmux configuration file to enforce session lock after inactivity, this is a finding.

Fix: F-32997r567806_fix

Configure the operating system to enforce session lock after a period of 15 minutes of inactivity by adding the following line to the "/etc/tmux.conf" global configuration file: set -g lock-after-time 900

Generate Mitigation Statement:

Checks: C-33023r743988_chk

Verify the operating system prevents a user from overriding settings for graphical user interfaces. Note: This requirement assumes the use of the RHEL 8 default graphical user interface, Gnome Shell. If the system does not have any graphical user interface installed, this requirement is Not Applicable. Determine which profile the system database is using with the following command: $ sudo grep system-db /etc/dconf/profile/user system-db:local Check that graphical settings are locked from non-privileged user modification with the following command: Note: The example below is using the database "local" for the system, so the path is "/etc/dconf/db/local.d". This path must be modified if a database other than "local" is being used. $ sudo grep -i lock-delay /etc/dconf/db/local.d/locks/* /org/gnome/desktop/screensaver/lock-delay If the command does not return at least the example result, this is a finding.

Fix: F-32998r743989_fix

Configure the operating system to prevent a user from overriding settings for graphical user interfaces. Create a database to contain the system-wide screensaver settings (if it does not already exist) with the following command: Note: The example below is using the database "local" for the system, so if the system is using another database in "/etc/dconf/profile/user", the file should be created under the appropriate subdirectory. $ sudo touch /etc/dconf/db/local.d/locks/session Add the following setting to prevent non-privileged users from modifying it: /org/gnome/desktop/screensaver/lock-delay

Generate Mitigation Statement:

Checks: C-33024r858742_chk

Verify the certificate of the user or group is mapped to the corresponding user or group in the "sssd.conf" file with the following command: Note: If the System Administrator demonstrates the use of an approved alternate multifactor authentication method, this requirement is not applicable. $ sudo cat /etc/sssd/sssd.conf [sssd] config_file_version = 2 services = pam, sudo, ssh domains = testing.test [pam] pam_cert_auth = True [domain/testing.test] id_provider = ldap [certmap/testing.test/rule_name] matchrule =&lt;SAN&gt;.*EDIPI@mil maprule = (userCertificate;binary={cert!bin}) domains = testing.test If the certmap section does not exist, ask the System Administrator to indicate how certificates are mapped to accounts. If there is no evidence of certificate mapping, this is a finding.

Fix: F-32999r818835_fix

Configure the operating system to map the authenticated identity to the user or group account by adding or modifying the certmap section of the "/etc/sssd/sssd.conf file based on the following example: [certmap/testing.test/rule_name] matchrule =<SAN>.*EDIPI@mil maprule = (userCertificate;binary={cert!bin}) domains = testing.test The "sssd" service must be restarted for the changes to take effect. To restart the "sssd" service, run the following command: $ sudo systemctl restart sssd.service

Generate Mitigation Statement:

Checks: C-33025r902726_chk

Verify the operating system uses "pwquality" to enforce the password complexity rules. Check for the use of "pwquality" in the password-auth file with the following command: $ sudo cat /etc/pam.d/password-auth | grep pam_pwquality password requisite pam_pwquality.so If the command does not return a line containing the value "pam_pwquality.so" as shown, or the line is commented out, this is a finding.

Fix: F-33000r902727_fix

Configure the operating system to use "pwquality" to enforce password complexity rules. Add the following line to the "/etc/pam.d/password-auth" file (or modify the line to have the required value): password requisite pam_pwquality.so

Generate Mitigation Statement:

Checks: C-33026r833312_chk

Verify the value for "ucredit" with the following command: $ sudo grep -r ucredit /etc/security/pwquality.conf* /etc/security/pwquality.conf:ucredit = -1 If the value of "ucredit" is a positive number or is commented out, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-33001r858770_fix

Configure the operating system to enforce password complexity by requiring that at least one uppercase character be used by setting the "ucredit" option. Add the following line to /etc/security/pwquality.conf (or modify the line to have the required value): ucredit = -1 Remove any configurations that conflict with the above value.

Generate Mitigation Statement:

Checks: C-33027r833314_chk

Verify the value for "lcredit" with the following command: $ sudo grep -r lcredit /etc/security/pwquality.conf* /etc/security/pwquality.conf:lcredit = -1 If the value of "lcredit" is a positive number or is commented out, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-33002r858772_fix

Configure the operating system to enforce password complexity by requiring that at least one lower-case character be used by setting the "lcredit" option. Add the following line to /etc/security/pwquality.conf (or modify the line to have the required value): lcredit = -1 Remove any configurations that conflict with the above value.

Generate Mitigation Statement:

Checks: C-33028r833316_chk

Verify the value for "dcredit" with the following command: $ sudo grep -r dcredit /etc/security/pwquality.conf* /etc/security/pwquality.conf:dcredit = -1 If the value of "dcredit" is a positive number or is commented out, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-33003r858774_fix

Configure the operating system to enforce password complexity by requiring that at least one numeric character be used by setting the "dcredit" option. Add the following line to /etc/security/pwquality.conf (or modify the line to have the required value): dcredit = -1 Remove any configurations that conflict with the above value.

Generate Mitigation Statement:

Checks: C-33029r833318_chk

Check for the value of the "maxclassrepeat" option with the following command: $ sudo grep -r maxclassrepeat /etc/security/pwquality.conf* /etc/security/pwquality.conf:maxclassrepeat = 4 If the value of "maxclassrepeat" is set to "0", more than "4" or is commented out, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-33004r858776_fix

Configure the operating system to require the change of the number of repeating characters of the same character class when passwords are changed by setting the "maxclassrepeat" option. Add the following line to "/etc/security/pwquality.conf" conf (or modify the line to have the required value): maxclassrepeat = 4 Remove any configurations that conflict with the above value.

Generate Mitigation Statement:

Checks: C-33030r833320_chk

Check for the value of the "maxrepeat" option with the following command: $ sudo grep -r maxrepeat /etc/security/pwquality.conf* /etc/security/pwquality.conf:maxrepeat = 3 If the value of "maxrepeat" is set to more than "3" or is commented out, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-33005r858778_fix

Configure the operating system to require the change of the number of repeating consecutive characters when passwords are changed by setting the "maxrepeat" option. Add the following line to "/etc/security/pwquality.conf conf" (or modify the line to have the required value): maxrepeat = 3 Remove any configurations that conflict with the above value.

Generate Mitigation Statement:

Checks: C-33031r833322_chk

Verify the value of the "minclass" option with the following command: $ sudo grep -r minclass /etc/security/pwquality.conf* /etc/security/pwquality.conf:minclass = 4 If the value of "minclass" is set to less than "4" or is commented out, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-33006r858780_fix

Configure the operating system to require the change of at least four character classes when passwords are changed by setting the "minclass" option. Add the following line to "/etc/security/pwquality.conf conf" (or modify the line to have the required value): minclass = 4 Remove any configurations that conflict with the above value.

Generate Mitigation Statement:

Checks: C-33032r833324_chk

Verify the value of the "difok" option with the following command: $ sudo grep -r difok /etc/security/pwquality.conf* /etc/security/pwquality.conf:difok = 8 If the value of "difok" is set to less than "8" or is commented out, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-33007r858782_fix

Configure the operating system to require the change of at least eight of the total number of characters when passwords are changed by setting the "difok" option. Add the following line to "/etc/security/pwquality.conf" (or modify the line to have the required value): difok = 8 Remove any configurations that conflict with the above value.

Generate Mitigation Statement:

Checks: C-33033r567838_chk

Check whether the minimum time period between password changes for each user account is one day or greater. $ sudo awk -F: '$4 &lt; 1 {print $1 " " $4}' /etc/shadow If any results are returned that are not associated with a system account, this is a finding.

Fix: F-33008r567839_fix

Configure non-compliant accounts to enforce a 24 hours/1 day minimum password lifetime: $ sudo chage -m 1 [user]

Generate Mitigation Statement:

Checks: C-33034r567841_chk

Verify the operating system enforces 24 hours/1 day as the minimum password lifetime for new user accounts. Check for the value of "PASS_MIN_DAYS" in "/etc/login.defs" with the following command: $ sudo grep -i pass_min_days /etc/login.defs PASS_MIN_DAYS 1 If the "PASS_MIN_DAYS" parameter value is not "1" or greater, or is commented out, this is a finding.

Fix: F-33009r567842_fix

Configure the operating system to enforce 24 hours/1 day as the minimum password lifetime. Add the following line in "/etc/login.defs" (or modify the line to have the required value): PASS_MIN_DAYS 1

Generate Mitigation Statement:

Checks: C-33035r646877_chk

Verify that RHEL 8 enforces a 60-day maximum password lifetime for new user accounts by running the following command: $ sudo grep -i pass_max_days /etc/login.defs PASS_MAX_DAYS 60 If the "PASS_MAX_DAYS" parameter value is greater than "60", or commented out, this is a finding.

Fix: F-33010r567845_fix

Configure RHEL 8 to enforce a 60-day maximum password lifetime. Add, or modify the following line in the "/etc/login.defs" file: PASS_MAX_DAYS 60

Generate Mitigation Statement:

Checks: C-33036r567847_chk

Check whether the maximum time period for existing passwords is restricted to 60 days with the following commands: $ sudo awk -F: '$5 &gt; 60 {print $1 " " $5}' /etc/shadow $ sudo awk -F: '$5 &lt;= 0 {print $1 " " $5}' /etc/shadow If any results are returned that are not associated with a system account, this is a finding.

Fix: F-33011r567848_fix

Configure non-compliant accounts to enforce a 60-day maximum password lifetime restriction. $ sudo chage -M 60 [user]

Generate Mitigation Statement:

Checks: C-33037r902756_chk

Verify the operating system is configured in the password-auth file to prohibit password reuse for a minimum of five generations. Check for the value of the "remember" argument in "/etc/pam.d/password-auth" with the following command: $ sudo grep -i remember /etc/pam.d/password-auth password requisite pam_pwhistory.so use_authtok remember=5 retry=3 If the line containing "pam_pwhistory.so" does not have the "remember" module argument set, is commented out, or the value of the "remember" module argument is set to less than "5", this is a finding.

Fix: F-33012r902757_fix

Configure the operating system in the password-auth file to prohibit password reuse for a minimum of five generations. Add the following line in "/etc/pam.d/password-auth" (or modify the line to have the required value): password requisite pam_pwhistory.so use_authtok remember=5 retry=3

Generate Mitigation Statement:

Checks: C-33038r833326_chk

Verify the operating system enforces a minimum 15-character password length. The "minlen" option sets the minimum number of characters in a new password. Check for the value of the "minlen" option with the following command: $ sudo grep -r minlen /etc/security/pwquality.conf* /etc/security/pwquality.conf:minlen = 15 If the command does not return a "minlen" value of 15 or greater, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-33013r858784_fix

Configure operating system to enforce a minimum 15-character password length. Add the following line to "/etc/security/pwquality.conf" (or modify the line to have the required value): minlen = 15 Remove any configurations that conflict with the above value.

Generate Mitigation Statement:

Checks: C-33039r567856_chk

Verify that RHEL 8 enforces a minimum 15-character password length for new user accounts by running the following command: $ sudo grep -i pass_min_len /etc/login.defs PASS_MIN_LEN 15 If the "PASS_MIN_LEN" parameter value is less than "15", or commented out, this is a finding.

Fix: F-33014r567857_fix

Configure operating system to enforce a minimum 15-character password length for new user accounts. Add, or modify the following line in the "/etc/login.defs" file: PASS_MIN_LEN 15

Generate Mitigation Statement:

Checks: C-33040r567859_chk

Verify that RHEL 8 contains no duplicate User IDs (UIDs) for interactive users. Check that the operating system contains no duplicate UIDs for interactive users with the following command: $ sudo awk -F ":" 'list[$3]++{print $1, $3}' /etc/passwd If output is produced, and the accounts listed are interactive user accounts, this is a finding.

Fix: F-33015r567860_fix

Edit the file "/etc/passwd" and provide each interactive user account that has a duplicate User ID (UID) with a unique UID.

Generate Mitigation Statement:

Checks: C-33041r567862_chk

Verify RHEL 8 uses multifactor authentication for local access to accounts. Note: If the System Administrator demonstrates the use of an approved alternate multifactor authentication method, this requirement is not applicable. Check that the "pam_cert_auth" setting is set to "true" in the "/etc/sssd/sssd.conf" file. Check that the "try_cert_auth" or "require_cert_auth" options are configured in both "/etc/pam.d/system-auth" and "/etc/pam.d/smartcard-auth" files with the following command: $ sudo grep cert_auth /etc/sssd/sssd.conf /etc/pam.d/* /etc/sssd/sssd.conf:pam_cert_auth = True /etc/pam.d/smartcard-auth:auth sufficient pam_sss.so try_cert_auth /etc/pam.d/system-auth:auth [success=done authinfo_unavail=ignore ignore=ignore default=die] pam_sss.so try_cert_auth If "pam_cert_auth" is not set to "true" in "/etc/sssd/sssd.conf", this is a finding. If "pam_sss.so" is not set to "try_cert_auth" or "require_cert_auth" in both the "/etc/pam.d/smartcard-auth" and "/etc/pam.d/system-auth" files, this is a finding.

Fix: F-33016r567863_fix

Configure RHEL 8 to use multifactor authentication for local access to accounts. Add or update the "pam_cert_auth" setting in the "/etc/sssd/sssd.conf" file to match the following line: [pam] pam_cert_auth = True Add or update "pam_sss.so" with "try_cert_auth" or "require_cert_auth" in the "/etc/pam.d/system-auth" and "/etc/pam.d/smartcard-auth" files based on the following examples: /etc/pam.d/smartcard-auth:auth sufficient pam_sss.so try_cert_auth /etc/pam.d/system-auth:auth [success=done authinfo_unavail=ignore ignore=ignore default=die] pam_sss.so try_cert_auth The "sssd" service must be restarted for the changes to take effect. To restart the "sssd" service, run the following command: $ sudo systemctl restart sssd.service

Generate Mitigation Statement:

Checks: C-33042r567865_chk

Verify the account identifiers (individuals, groups, roles, and devices) are disabled after 35 days of inactivity with the following command: Check the account inactivity value by performing the following command: $ sudo grep -i inactive /etc/default/useradd INACTIVE=35 If "INACTIVE" is set to "-1", a value greater than "35", or is commented out, this is a finding.

Fix: F-33017r567866_fix

Configure RHEL 8 to disable account identifiers after 35 days of inactivity after the password expiration. Run the following command to change the configuration for useradd: $ sudo useradd -D -f 35 DoD recommendation is 35 days, but a lower value is acceptable. The value "-1" will disable this feature, and "0" will disable the account immediately after the password expires.

Generate Mitigation Statement:

Checks: C-33043r902729_chk

Verify temporary accounts have been provisioned with an expiration date of 72 hours. For every existing temporary account, run the following command to obtain its account expiration information: $ sudo chage -l &lt;temporary_account_name&gt; | grep -i "account expires" Verify each of these accounts has an expiration date set within 72 hours. If any temporary accounts have no expiration date set or do not expire within 72 hours, this is a finding.

Fix: F-33018r902730_fix

Configure the operating system to expire temporary accounts after 72 hours with the following command: $ sudo chage -E $(date -d +3days +%Y-%m-%d) <temporary_account_name>

Generate Mitigation Statement:

Checks: C-33044r833328_chk

Verify the value for "ocredit" with the following command: $ sudo grep -r ocredit /etc/security/pwquality.conf* /etc/security/pwquality.conf:ocredit = -1 If the value of "ocredit" is a positive number or is commented out, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-33019r858786_fix

Configure the operating system to enforce password complexity by requiring that at least one special character be used by setting the "ocredit" option. Add the following line to /etc/security/pwquality.conf (or modify the line to have the required value): ocredit = -1 Remove any configurations that conflict with the above value.

Generate Mitigation Statement:

Checks: C-33045r567874_chk

Verify that the SSSD prohibits the use of cached authentications after one day. Note: If smart card authentication is not being used on the system this item is Not Applicable. Check that SSSD allows cached authentications with the following command: $ sudo grep cache_credentials /etc/sssd/sssd.conf cache_credentials = true If "cache_credentials" is set to "false" or missing from the configuration file, this is not a finding and no further checks are required. If "cache_credentials" is set to "true", check that SSSD prohibits the use of cached authentications after one day with the following command: $ sudo grep offline_credentials_expiration /etc/sssd/sssd.conf offline_credentials_expiration = 1 If "offline_credentials_expiration" is not set to a value of "1", this is a finding.

Fix: F-33020r567875_fix

Configure the SSSD to prohibit the use of cached authentications after one day. Add or change the following line in "/etc/sssd/sssd.conf" just below the line "[pam]". offline_credentials_expiration = 1

Generate Mitigation Statement:

Checks: C-33046r833330_chk

Verify RHEL 8 prevents the use of dictionary words for passwords. Determine if the field "dictcheck" is set with the following command: $ sudo grep -r dictcheck /etc/security/pwquality.conf* /etc/security/pwquality.conf:dictcheck=1 If the "dictcheck" parameter is not set to "1", or is commented out, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-33021r858788_fix

Configure RHEL 8 to prevent the use of dictionary words for passwords. Add or update the following line in the "/etc/security/pwquality.conf" file or a configuration file in the /etc/pwquality.conf.d/ directory to contain the "dictcheck" parameter: dictcheck=1 Remove any configurations that conflict with the above value.

Generate Mitigation Statement:

Checks: C-33047r567880_chk

Verify the operating system enforces a delay of at least four seconds between console logon prompts following a failed logon attempt with the following command: $ sudo grep -i fail_delay /etc/login.defs FAIL_DELAY 4 If the value of "FAIL_DELAY" is not set to "4" or greater, or the line is commented out, this is a finding.

Fix: F-33022r567881_fix

Configure the operating system to enforce a delay of at least four seconds between logon prompts following a failed console logon attempt. Modify the "/etc/login.defs" file to set the "FAIL_DELAY" parameter to "4" or greater: FAIL_DELAY 4

Generate Mitigation Statement:

Checks: C-33048r567883_chk

Verify all accounts on the system are assigned to an active system, application, or user account. Obtain the list of authorized system accounts from the Information System Security Officer (ISSO). Check the system accounts on the system with the following command: $ sudo more /etc/passwd root:x:0:0:root:/root:/bin/bash bin:x:1:1:bin:/bin:/sbin/nologin daemon:x:2:2:daemon:/sbin:/sbin/nologin sync:x:5:0:sync:/sbin:/bin/sync shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt games:x:12:100:games:/usr/games:/sbin/nologin gopher:x:13:30:gopher:/var/gopher:/sbin/nologin Accounts such as "games" and "gopher" are not authorized accounts as they do not support authorized system functions. If the accounts on the system do not match the provided documentation, or accounts that do not support an authorized system function are present, this is a finding.

Fix: F-33023r567884_fix

Configure the system so all accounts on the system are assigned to an active system, application, or user account. Remove accounts that do not support approved system activities or that allow for a normal user to perform administrative-level actions. Document all authorized accounts on the system.

Generate Mitigation Statement:

Checks: C-33051r858716_chk

Verify SSH provides users with feedback on when account accesses last occurred with the following command: $ sudo grep -ir printlastlog /etc/ssh/sshd_config* PrintLastLog yes If the "PrintLastLog" keyword is set to "no", is missing, or is commented out, this is a finding. If conflicting results are returned, this is a finding.

Fix: F-33026r567893_fix

Configure SSH to provide users with feedback on when account accesses last occurred by setting the required configuration options in "/etc/pam.d/sshd" or in the "sshd_config" file used by the system ("/etc/ssh/sshd_config" will be used in the example) (this file may be named differently or be in a different location if using a version of SSH that is provided by a third-party vendor). Modify the "PrintLastLog" line in "/etc/ssh/sshd_config" to match the following: PrintLastLog yes The SSH service must be restarted for changes to "sshd_config" to take effect.

Generate Mitigation Statement:

Checks: C-33052r567895_chk

Verify the operating system defines default permissions for all authenticated users in such a way that the user can only read and modify their own files. Check for the value of the "UMASK" parameter in "/etc/login.defs" file with the following command: Note: If the value of the "UMASK" parameter is set to "000" in "/etc/login.defs" file, the Severity is raised to a CAT I. # grep -i umask /etc/login.defs UMASK 077 If the value for the "UMASK" parameter is not "077", or the "UMASK" parameter is missing or is commented out, this is a finding.

Fix: F-33027r567896_fix

Configure the operating system to define default permissions for all authenticated users in such a way that the user can only read and modify their own files. Add or edit the line for the "UMASK" parameter in "/etc/login.defs" file to "077": UMASK 077

Generate Mitigation Statement:

Checks: C-33053r858731_chk

Verify that the default umask for all local interactive users is "077". Identify the locations of all local interactive user home directories by looking at the "/etc/passwd" file. Check all local interactive user initialization files for interactive users with the following command: Note: The example is for a system that is configured to create users home directories in the "/home" directory. $ sudo grep -ir ^umask /home | grep -v '.bash_history' If any local interactive user initialization files are found to have a umask statement that has a value less restrictive than "077", this is a finding.

Fix: F-33028r567899_fix

Remove the umask statement from all local interactive user's initialization files. If the account is for an application, the requirement for a umask less restrictive than "077" can be documented with the Information System Security Officer, but the user agreement for access to the account must specify that the local interactive user must log on to their account first and then switch the user to the application account with the correct option to gain the account's environment variables.

Generate Mitigation Statement:

Checks: C-33054r792900_chk

Verify that the umask default for installed shells is "077". Check for the value of the "UMASK" parameter in the "/etc/bashrc", "/etc/csh.cshrc" and "/etc/profile" files with the following command: Note: If the value of the "UMASK" parameter is set to "000" in the "/etc/bashrc" the "/etc/csh.cshrc" or the "/etc/profile" files, the Severity is raised to a CAT I. # grep -i umask /etc/bashrc /etc/csh.cshrc /etc/profile /etc/bashrc: umask 077 /etc/bashrc: umask 077 /etc/csh.cshrc: umask 077 /etc/csh.cshrc: umask 077 /etc/profile: umask 077 /etc/profile: umask 077 If the value for the "UMASK" parameter is not "077", or the "UMASK" parameter is missing or is commented out, this is a finding.

Fix: F-33029r792901_fix

Configure the operating system to define default permissions for all authenticated users in such a way that the user can only read and modify their own files. Add or edit the lines for the "UMASK" parameter in the "/etc/bashrc", "/etc/csh.cshrc" and "/etc/profile"files to "077": UMASK 077

Generate Mitigation Statement:

Checks: C-33055r567904_chk

Verify RHEL 8 audits the execution of privileged functions. Check if RHEL 8 is configured to audit the execution of the "execve" system call, by running the following command: $ sudo grep execve /etc/audit/audit.rules -a always,exit -F arch=b32 -S execve -C uid!=euid -F euid=0 -k execpriv -a always,exit -F arch=b64 -S execve -C uid!=euid -F euid=0 -k execpriv -a always,exit -F arch=b32 -S execve -C gid!=egid -F egid=0 -k execpriv -a always,exit -F arch=b64 -S execve -C gid!=egid -F egid=0 -k execpriv If the command does not return all lines, or the lines are commented out, this is a finding.

Fix: F-33030r567905_fix

Configure RHEL 8 to audit the execution of the "execve" system call. Add or update the following file system rules to "/etc/audit/rules.d/audit.rules": -a always,exit -F arch=b32 -S execve -C uid!=euid -F euid=0 -k execpriv -a always,exit -F arch=b64 -S execve -C uid!=euid -F euid=0 -k execpriv -a always,exit -F arch=b32 -S execve -C gid!=egid -F egid=0 -k execpriv -a always,exit -F arch=b64 -S execve -C gid!=egid -F egid=0 -k execpriv The audit daemon must be restarted for the changes to take effect.

Generate Mitigation Statement:

Checks: C-33056r743994_chk

Verify that "rsyslog" is configured to log cron events with the following command: Note: If another logging package is used, substitute the utility configuration file for "/etc/rsyslog.conf" or "/etc/rsyslog.d/*.conf" files. $ sudo grep -s cron /etc/rsyslog.conf /etc/rsyslog.d/*.conf /etc/rsyslog.conf:*.info;mail.none;authpriv.none;cron.none /var/log/messages /etc/rsyslog.conf:# Log cron stuff /etc/rsyslog.conf:cron.* /var/log/cron If the command does not return a response, check for cron logging all facilities with the following command. $ sudo grep -s /var/log/messages /etc/rsyslog.conf /etc/rsyslog.d/*.conf /etc/rsyslog.conf:*.info;mail.none;authpriv.none;cron.none /var/log/messages If "rsyslog" is not logging messages for the cron facility or all facilities, this is a finding.

Fix: F-33031r743995_fix

Configure "rsyslog" to log all cron messages by adding or updating the following line to "/etc/rsyslog.conf" or a configuration file in the /etc/rsyslog.d/ directory: cron.* /var/log/cron The rsyslog daemon must be restarted for the changes to take effect: $ sudo systemctl restart rsyslog.service

Generate Mitigation Statement:

Checks: C-33057r567910_chk

Verify that the SA and ISSO (at a minimum) are notified in the event of an audit processing failure. Check that RHEL 8 notifies the SA and ISSO (at a minimum) in the event of an audit processing failure with the following command: $ sudo grep action_mail_acct /etc/audit/auditd.conf action_mail_acct = root If the value of the "action_mail_acct" keyword is not set to "root" and/or other accounts for security personnel, the "action_mail_acct" keyword is missing, or the retuned line is commented out, ask the system administrator to indicate how they and the ISSO are notified of an audit process failure. If there is no evidence of the proper personnel being notified of an audit processing failure, this is a finding.

Fix: F-33032r567911_fix

Configure "auditd" service to notify the SA and ISSO in the event of an audit processing failure. Edit the following line in "/etc/audit/auditd.conf" to ensure that administrators are notified via email for those situations: action_mail_acct = root

Generate Mitigation Statement:

Checks: C-33058r567913_chk

Verify that the administrators are notified in the event of an audit processing failure. Check that the "/etc/aliases" file has a defined value for "root". $ sudo grep "postmaster:\s*root$" /etc/aliases If the command does not return a line, or the line is commented out, ask the system administrator to indicate how they and the ISSO are notified of an audit process failure. If there is no evidence of the proper personnel being notified of an audit processing failure, this is a finding.

Fix: F-33033r567914_fix

Configure RHEL 8 to notify administrators in the event of an audit processing failure. Add/update the following line in "/etc/aliases": postmaster: root

Generate Mitigation Statement:

Checks: C-33059r567916_chk

Verify RHEL 8 takes the appropriate action when an audit processing failure occurs. Check that RHEL 8 takes the appropriate action when an audit processing failure occurs with the following command: $ sudo grep disk_error_action /etc/audit/auditd.conf disk_error_action = HALT If the value of the "disk_error_action" option is not "SYSLOG", "SINGLE", or "HALT", or the line is commented out, ask the system administrator to indicate how the system takes appropriate action when an audit process failure occurs. If there is no evidence of appropriate action, this is a finding.

Fix: F-33034r567917_fix

Configure RHEL 8 to shut down by default upon audit failure (unless availability is an overriding concern). Add or update the following line (depending on configuration "disk_error_action" can be set to "SYSLOG" or "SINGLE" depending on configuration) in "/etc/audit/auditd.conf" file: disk_error_action = HALT If availability has been determined to be more important, and this decision is documented with the ISSO, configure the operating system to notify system administration staff and ISSO staff in the event of an audit processing failure by setting the "disk_error_action" to "SYSLOG".

Generate Mitigation Statement:

Checks: C-33061r567922_chk

Verify RHEL 8 takes the appropriate action when the audit storage volume is full. Check that RHEL 8 takes the appropriate action when the audit storage volume is full with the following command: $ sudo grep disk_full_action /etc/audit/auditd.conf disk_full_action = HALT If the value of the "disk_full_action" option is not "SYSLOG", "SINGLE", or "HALT", or the line is commented out, ask the system administrator to indicate how the system takes appropriate action when an audit storage volume is full. If there is no evidence of appropriate action, this is a finding.

Fix: F-33036r567923_fix

Configure RHEL 8 to shut down by default upon audit failure (unless availability is an overriding concern). Add or update the following line (depending on configuration "disk_full_action" can be set to "SYSLOG" or "SINGLE" depending on configuration) in "/etc/audit/auditd.conf" file: disk_full_action = HALT If availability has been determined to be more important, and this decision is documented with the ISSO, configure the operating system to notify system administration staff and ISSO staff in the event of an audit processing failure by setting the "disk_full_action" to "SYSLOG".

Generate Mitigation Statement:

Checks: C-33062r567925_chk

Verify the RHEL 8 Audit Daemon is configured to include local events, with the following command: $ sudo grep local_events /etc/audit/auditd.conf local_events = yes If the value of the "local_events" option is not set to "yes", or the line is commented out, this is a finding.

Fix: F-33037r567926_fix

Configure RHEL 8 to audit local events on the system. Add or update the following line in "/etc/audit/auditd.conf" file: local_events = yes

Generate Mitigation Statement:

Checks: C-33063r567928_chk

Verify the RHEL 8 Audit Daemon is configured to label all off-loaded audit logs, with the following command: $ sudo grep "name_format" /etc/audit/auditd.conf name_format = hostname If the "name_format" option is not "hostname", "fqd", or "numeric", or the line is commented out, this is a finding.

Fix: F-33038r567929_fix

Edit the /etc/audit/auditd.conf file and add or update the "name_format" option: name_format = hostname The audit daemon must be restarted for changes to take effect.

Generate Mitigation Statement:

Checks: C-33065r567934_chk

Verify the audit logs have a mode of "0600" or less permissive. First, determine where the audit logs are stored with the following command: $ sudo grep -iw log_file /etc/audit/auditd.conf log_file = /var/log/audit/audit.log Using the location of the audit log file, check if the audit log has a mode of "0600" or less permissive with the following command: $ sudo stat -c "%a %n" /var/log/audit/audit.log 600 /var/log/audit/audit.log If the audit log has a mode more permissive than "0600", this is a finding.

Fix: F-33040r902732_fix

Configure the audit log to be protected from unauthorized read access by setting the correct permissive mode with the following command: $ sudo chmod 0600 /var/log/audit/audit.log

Generate Mitigation Statement:

Checks: C-33066r567937_chk

Verify the audit logs are owned by "root". First, determine where the audit logs are stored with the following command: $ sudo grep -iw log_file /etc/audit/auditd.conf log_file = /var/log/audit/audit.log Using the location of the audit log file, determine if the audit log is owned by "root" using the following command: $ sudo ls -al /var/log/audit/audit.log rw------- 2 root root 23 Jun 11 11:56 /var/log/audit/audit.log If the audit log is not owned by "root", this is a finding.

Fix: F-33041r567938_fix

Configure the audit log to be protected from unauthorized read access, by setting the correct owner as "root" with the following command: $ sudo chown root [audit_log_file] Replace "[audit_log_file]" to the correct audit log path, by default this location is "/var/log/audit/audit.log".

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Checks: C-33067r567940_chk

Verify the audit logs are group-owned by "root". First determine where the audit logs are stored with the following command: $ sudo grep -iw log_file /etc/audit/auditd.conf log_file = /var/log/audit/audit.log Using the location of the audit log file, determine if the audit log is group-owned by "root" using the following command: $ sudo ls -al /var/log/audit/audit.log rw------- 2 root root 23 Jun 11 11:56 /var/log/audit/audit.log If the audit log is not group-owned by "root", this is a finding.

Fix: F-33042r567941_fix

Configure the audit log to be owned by root by configuring the log group in the /etc/audit/auditd.conf file: log_group = root

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Checks: C-33068r567943_chk

Verify the audit log directory is owned by "root" to prevent unauthorized read access. Determine where the audit logs are stored with the following command: $ sudo grep -iw log_file /etc/audit/auditd.conf log_file = /var/log/audit/audit.log Determine the owner of the audit log directory by using the output of the above command (ex: "/var/log/audit/"). Run the following command with the correct audit log directory path: $ sudo ls -ld /var/log/audit drw------- 2 root root 23 Jun 11 11:56 /var/log/audit If the audit log directory is not owned by "root", this is a finding.

Fix: F-33043r567944_fix

Configure the audit log to be protected from unauthorized read access, by setting the correct owner as "root" with the following command: $ sudo chown root [audit_log_directory] Replace "[audit_log_directory]" with the correct audit log directory path, by default this location is usually "/var/log/audit".

Generate Mitigation Statement:

Checks: C-33069r567946_chk

Verify the audit log directory is group-owned by "root" to prevent unauthorized read access. Determine where the audit logs are stored with the following command: $ sudo grep -iw log_file /etc/audit/auditd.conf log_file = /var/log/audit/audit.log Determine the group owner of the audit log directory by using the output of the above command (ex: "/var/log/audit/"). Run the following command with the correct audit log directory path: $ sudo ls -ld /var/log/audit drw------- 2 root root 23 Jun 11 11:56 /var/log/audit If the audit log directory is not group-owned by "root", this is a finding.

Fix: F-33044r567947_fix

Configure the audit log to be protected from unauthorized read access by setting the correct group-owner as "root" with the following command: $ sudo chgrp root [audit_log_directory] Replace "[audit_log_directory]" with the correct audit log directory path, by default this location is usually "/var/log/audit".

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Checks: C-33070r567949_chk

Verify the audit log directories have a mode of "0700" or less permissive by first determining where the audit logs are stored with the following command: $ sudo grep -iw log_file /etc/audit/auditd.conf log_file = /var/log/audit/audit.log Using the location of the audit log, determine the directory where the audit logs are stored (ex: "/var/log/audit"). Run the following command to determine the permissions for the audit log folder: $ sudo stat -c "%a %n" /var/log/audit 700 /var/log/audit If the audit log directory has a mode more permissive than "0700", this is a finding.

Fix: F-33045r567950_fix

Configure the audit log directory to be protected from unauthorized read access by setting the correct permissive mode with the following command: $ sudo chmod 0700 [audit_log_directory] Replace "[audit_log_directory]" to the correct audit log directory path, by default this location is "/var/log/audit".

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Checks: C-33071r567952_chk

Verify the audit system prevents unauthorized changes with the following command: $ sudo grep "^\s*[^#]" /etc/audit/audit.rules | tail -1 -e 2 If the audit system is not set to be immutable by adding the "-e 2" option to the "/etc/audit/audit.rules", this is a finding.

Fix: F-33046r567953_fix

Configure the audit system to set the audit rules to be immutable by adding the following line to "/etc/audit/rules.d/audit.rules" -e 2 Note: Once set, the system must be rebooted for auditing to be changed. It is recommended to add this option as the last step in securing the system.

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Checks: C-33072r567955_chk

Verify the audit system prevents unauthorized changes to logon UIDs with the following command: $ sudo grep -i immutable /etc/audit/audit.rules --loginuid-immutable If the login UIDs are not set to be immutable by adding the "--loginuid-immutable" option to the "/etc/audit/audit.rules", this is a finding.

Fix: F-33047r567956_fix

Configure the audit system to set the logon UIDs to be immutable by adding the following line to "/etc/audit/rules.d/audit.rules" --loginuid-immutable

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Checks: C-33073r567958_chk

Verify RHEL 8 generates audit records for all account creations, modifications, disabling, and termination events that affect "/etc/shadow". Check the auditing rules in "/etc/audit/audit.rules" with the following command: $ sudo grep /etc/shadow /etc/audit/audit.rules -w /etc/shadow -p wa -k identity If the command does not return a line, or the line is commented out, this is a finding.

Fix: F-33048r567959_fix

Configure RHEL 8 to generate audit records for all account creations, modifications, disabling, and termination events that affect "/etc/shadow". Add or update the following file system rule to "/etc/audit/rules.d/audit.rules": -w /etc/shadow -p wa -k identity The audit daemon must be restarted for the changes to take effect.

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Checks: C-33074r567961_chk

Verify RHEL 8 generates audit records for all account creations, modifications, disabling, and termination events that affect "/etc/security/opasswd". Check the auditing rules in "/etc/audit/audit.rules" with the following command: $ sudo grep /etc/security/opasswd /etc/audit/audit.rules -w /etc/security/opasswd -p wa -k identity If the command does not return a line, or the line is commented out, this is a finding.

Fix: F-33049r567962_fix

Configure RHEL 8 to generate audit records for all account creations, modifications, disabling, and termination events that affect "/etc/security/opasswd". Add or update the following file system rule to "/etc/audit/rules.d/audit.rules": -w /etc/security/opasswd -p wa -k identity The audit daemon must be restarted for the changes to take effect.

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Checks: C-33075r567964_chk

Verify RHEL 8 generates audit records for all account creations, modifications, disabling, and termination events that affect "/etc/passwd". Check the auditing rules in "/etc/audit/audit.rules" with the following command: $ sudo grep /etc/passwd /etc/audit/audit.rules -w /etc/passwd -p wa -k identity If the command does not return a line, or the line is commented out, this is a finding.

Fix: F-33050r567965_fix

Configure RHEL 8 to generate audit records for all account creations, modifications, disabling, and termination events that affect "/etc/passwd". Add or update the following file system rule to "/etc/audit/rules.d/audit.rules": -w /etc/passwd -p wa -k identity The audit daemon must be restarted for the changes to take effect.

Generate Mitigation Statement:

Checks: C-33076r567967_chk