Red Hat Enterprise Linux 6 Security Technical Implementation Guide

V001.022R1 2019-01-25       U_RedHat_6_V1R22_STIG_SCAP_1-2_Benchmark.xml
The Red Hat Enterprise Linux 6 Security Technical Implementation Guide (STIG) is published as a tool to improve the security of Department of Defense (DoD) information systems. Comments or proposed revisions to this document should be sent via e-mail to the following address: [email protected]
Vuln Rule Version CCI Severity Title Description
SV-50237r1_rule RHEL-06-000526 CCI-000366 LOW Automated file system mounting tools must not be enabled unless needed. All filesystems that are required for the successful operation of the system should be explicitly listed in "/etc/fstab" by an administrator. New filesystems should not be arbitrarily introduced via the automounter. The "autofs" daemon mounts and unmounts filesystems, such as user home directories shared via NFS, on demand. In addition, autofs can be used to handle removable media, and the default configuration provides the cdrom device as "/misc/cd". However, this method of providing access to removable media is not common, so autofs can almost always be disabled if NFS is not in use. Even if NFS is required, it is almost always possible to configure filesystem mounts statically by editing "/etc/fstab" rather than relying on the automounter.
SV-50238r4_rule RHEL-06-000525 CCI-000169 LOW Auditing must be enabled at boot by setting a kernel parameter. Each process on the system carries an "auditable" flag which indicates whether its activities can be audited. Although "auditd" takes care of enabling this for all processes which launch after it does, adding the kernel argument ensures it is set for every process during boot.
SV-50243r1_rule RHEL-06-000036 CCI-000366 MEDIUM The /etc/gshadow file must be owned by root. The "/etc/gshadow" file contains group password hashes. Protection of this file is critical for system security.
SV-50248r1_rule RHEL-06-000037 CCI-000366 MEDIUM The /etc/gshadow file must be group-owned by root. The "/etc/gshadow" file contains group password hashes. Protection of this file is critical for system security.
SV-50249r1_rule RHEL-06-000038 CCI-000366 MEDIUM The /etc/gshadow file must have mode 0000. The /etc/gshadow file contains group password hashes. Protection of this file is critical for system security.
SV-50250r1_rule RHEL-06-000039 CCI-000366 MEDIUM The /etc/passwd file must be owned by root. The "/etc/passwd" file contains information about the users that are configured on the system. Protection of this file is critical for system security.
SV-50251r1_rule RHEL-06-000040 CCI-000366 MEDIUM The /etc/passwd file must be group-owned by root. The "/etc/passwd" file contains information about the users that are configured on the system. Protection of this file is critical for system security.
SV-50255r1_rule RHEL-06-000001 CCI-000366 LOW The system must use a separate file system for /tmp. The "/tmp" partition is used as temporary storage by many programs. Placing "/tmp" in its own partition enables the setting of more restrictive mount options, which can help protect programs which use it.
SV-50256r1_rule RHEL-06-000002 CCI-000366 LOW The system must use a separate file system for /var. Ensuring that "/var" is mounted on its own partition enables the setting of more restrictive mount options. This helps protect system services such as daemons or other programs which use it. It is not uncommon for the "/var" directory to contain world-writable directories, installed by other software packages.
SV-50257r1_rule RHEL-06-000041 CCI-000366 MEDIUM The /etc/passwd file must have mode 0644 or less permissive. If the "/etc/passwd" file is writable by a group-owner or the world the risk of its compromise is increased. The file contains the list of accounts on the system and associated information, and protection of this file is critical for system security.
SV-50258r1_rule RHEL-06-000042 CCI-000366 MEDIUM The /etc/group file must be owned by root. The "/etc/group" file contains information regarding groups that are configured on the system. Protection of this file is important for system security.
SV-50259r1_rule RHEL-06-000043 CCI-000366 MEDIUM The /etc/group file must be group-owned by root. The "/etc/group" file contains information regarding groups that are configured on the system. Protection of this file is important for system security.
SV-50261r1_rule RHEL-06-000044 CCI-000366 MEDIUM The /etc/group file must have mode 0644 or less permissive. The "/etc/group" file contains information regarding groups that are configured on the system. Protection of this file is important for system security.
SV-50263r1_rule RHEL-06-000003 CCI-000366 LOW The system must use a separate file system for /var/log. Placing "/var/log" in its own partition enables better separation between log files and other files in "/var/".
SV-50267r1_rule RHEL-06-000004 CCI-000137 LOW The system must use a separate file system for the system audit data path. Placing "/var/log/audit" in its own partition enables better separation between audit files and other files, and helps ensure that auditing cannot be halted due to the partition running out of space.
SV-50269r3_rule RHEL-06-000047 CCI-001499 MEDIUM All system command files must have mode 755 or less permissive. System binaries are executed by privileged users, as well as system services, and restrictive permissions are necessary to ensure execution of these programs cannot be co-opted.
SV-50270r2_rule RHEL-06-000005 CCI-000138 MEDIUM The audit system must alert designated staff members when the audit storage volume approaches capacity. Notifying administrators of an impending disk space problem may allow them to take corrective action prior to any disruption.
SV-50272r1_rule RHEL-06-000048 CCI-001499 MEDIUM All system command files must be owned by root. System binaries are executed by privileged users as well as system services, and restrictive permissions are necessary to ensure that their execution of these programs cannot be co-opted.
SV-50273r1_rule RHEL-06-000007 CCI-000366 LOW The system must use a separate file system for user home directories. Ensuring that "/home" is mounted on its own partition enables the setting of more restrictive mount options, and also helps ensure that users cannot trivially fill partitions used for log or audit data storage.
SV-50275r3_rule RHEL-06-000050 CCI-000205 MEDIUM The system must require passwords to contain a minimum of 15 characters. Requiring a minimum password length makes password cracking attacks more difficult by ensuring a larger search space. However, any security benefit from an onerous requirement must be carefully weighed against usability problems, support costs, or counterproductive behavior that may result. While it does not negate the password length requirement, it is preferable to migrate from a password-based authentication scheme to a stronger one based on PKI (public key infrastructure).
SV-50276r3_rule RHEL-06-000008 CCI-000352 HIGH Vendor-provided cryptographic certificates must be installed to verify the integrity of system software. The Red Hat GPG keys are necessary to cryptographically verify packages are from Red Hat.
SV-50277r1_rule RHEL-06-000051 CCI-000198 MEDIUM Users must not be able to change passwords more than once every 24 hours. Setting the minimum password age protects against users cycling back to a favorite password after satisfying the password reuse requirement.
SV-50279r1_rule RHEL-06-000053 CCI-000199 MEDIUM User passwords must be changed at least every 60 days. Setting the password maximum age ensures users are required to periodically change their passwords. This could possibly decrease the utility of a stolen password. Requiring shorter password lifetimes increases the risk of users writing down the password in a convenient location subject to physical compromise.
SV-50280r1_rule RHEL-06-000054 CCI-000366 LOW Users must be warned 7 days in advance of password expiration. Setting the password warning age enables users to make the change at a practical time.
SV-50282r2_rule RHEL-06-000056 CCI-000194 LOW The system must require passwords to contain at least one numeric character. Requiring digits makes password guessing attacks more difficult by ensuring a larger search space.
SV-50283r1_rule RHEL-06-000013 CCI-000663 MEDIUM The system package management tool must cryptographically verify the authenticity of system software packages during installation. Ensuring the validity of packages' cryptographic signatures prior to installation ensures the provenance of the software and protects against malicious tampering.
SV-50288r1_rule RHEL-06-000015 CCI-000663 LOW The system package management tool must cryptographically verify the authenticity of all software packages during installation. Ensuring all packages' cryptographic signatures are valid prior to installation ensures the provenance of the software and protects against malicious tampering.
SV-50290r1_rule RHEL-06-000016 CCI-001069 MEDIUM A file integrity tool must be installed. The AIDE package must be installed if it is to be available for integrity checking.
SV-50291r6_rule RHEL-06-000503 CCI-000086 MEDIUM The operating system must enforce requirements for the connection of mobile devices to operating systems. USB storage devices such as thumb drives can be used to introduce unauthorized software and other vulnerabilities. Support for these devices should be disabled and the devices themselves should be tightly controlled.
SV-50292r1_rule RHEL-06-000019 CCI-001436 HIGH There must be no .rhosts or hosts.equiv files on the system. Trust files are convenient, but when used in conjunction with the R-services, they can allow unauthenticated access to a system.
SV-50293r1_rule RHEL-06-000027 CCI-000770 MEDIUM The system must prevent the root account from logging in from virtual consoles. Preventing direct root login to virtual console devices helps ensure accountability for actions taken on the system using the root account.
SV-50295r1_rule RHEL-06-000028 CCI-000770 LOW The system must prevent the root account from logging in from serial consoles. Preventing direct root login to serial port interfaces helps ensure accountability for actions taken on the systems using the root account.
SV-50296r1_rule RHEL-06-000384 CCI-000162 MEDIUM Audit log files must be owned by root. If non-privileged users can write to audit logs, audit trails can be modified or destroyed.
SV-50298r3_rule RHEL-06-000030 CCI-000366 HIGH The system must not have accounts configured with blank or null passwords. If an account has an empty password, anyone could log in and run commands with the privileges of that account. Accounts with empty passwords should never be used in operational environments.
SV-50299r1_rule RHEL-06-000383 CCI-000163 MEDIUM Audit log files must have mode 0640 or less permissive. If users can write to audit logs, audit trails can be modified or destroyed.
SV-50300r1_rule RHEL-06-000031 CCI-000366 MEDIUM The /etc/passwd file must not contain password hashes. The hashes for all user account passwords should be stored in the file "/etc/shadow" and never in "/etc/passwd", which is readable by all users.
SV-50301r2_rule RHEL-06-000032 CCI-000366 MEDIUM The root account must be the only account having a UID of 0. An account has root authority if it has a UID of 0. Multiple accounts with a UID of 0 afford more opportunity for potential intruders to guess a password for a privileged account. Proper configuration of sudo is recommended to afford multiple system administrators access to root privileges in an accountable manner.
SV-50302r4_rule RHEL-06-000357 CCI-001452 MEDIUM The system must disable accounts after excessive login failures within a 15-minute interval. Locking out user accounts after a number of incorrect attempts within a specific period of time prevents direct password guessing attacks.
SV-50303r1_rule RHEL-06-000033 CCI-000366 MEDIUM The /etc/shadow file must be owned by root. The "/etc/shadow" file contains the list of local system accounts and stores password hashes. Protection of this file is critical for system security. Failure to give ownership of this file to root provides the designated owner with access to sensitive information which could weaken the system security posture.
SV-50304r1_rule RHEL-06-000034 CCI-000366 MEDIUM The /etc/shadow file must be group-owned by root. The "/etc/shadow" file stores password hashes. Protection of this file is critical for system security.
SV-50305r1_rule RHEL-06-000035 CCI-000366 MEDIUM The /etc/shadow file must have mode 0000. The "/etc/shadow" file contains the list of local system accounts and stores password hashes. Protection of this file is critical for system security. Failure to give ownership of this file to root provides the designated owner with access to sensitive information which could weaken the system security posture.
SV-50312r2_rule RHEL-06-000082 CCI-000366 MEDIUM IP forwarding for IPv4 must not be enabled, unless the system is a router. IP forwarding permits the kernel to forward packets from one network interface to another. The ability to forward packets between two networks is only appropriate for systems acting as routers.
SV-50313r2_rule RHEL-06-000117 CCI-001100 MEDIUM The operating system must prevent public IPv4 access into an organizations internal networks, except as appropriately mediated by managed interfaces employing boundary protection devices. The "iptables" service provides the system's host-based firewalling capability for IPv4 and ICMP.
SV-50315r5_rule RHEL-06-000124 CCI-000382 MEDIUM The Datagram Congestion Control Protocol (DCCP) must be disabled unless required. Disabling DCCP protects the system against exploitation of any flaws in its implementation.
SV-50316r5_rule RHEL-06-000125 CCI-000382 MEDIUM The Stream Control Transmission Protocol (SCTP) must be disabled unless required. Disabling SCTP protects the system against exploitation of any flaws in its implementation.
SV-50317r3_rule RHEL-06-000126 CCI-000382 LOW The Reliable Datagram Sockets (RDS) protocol must be disabled unless required. Disabling RDS protects the system against exploitation of any flaws in its implementation.
SV-50318r5_rule RHEL-06-000127 CCI-000382 MEDIUM The Transparent Inter-Process Communication (TIPC) protocol must be disabled unless required. Disabling TIPC protects the system against exploitation of any flaws in its implementation.
SV-50319r2_rule RHEL-06-000133 CCI-001314 MEDIUM All rsyslog-generated log files must be owned by root. The log files generated by rsyslog contain valuable information regarding system configuration, user authentication, and other such information. Log files should be protected from unauthorized access.
SV-50323r3_rule RHEL-06-000167 CCI-000169 LOW The audit system must be configured to audit all attempts to alter system time through settimeofday. Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time (such as sshd). All changes to the system time should be audited.
SV-50324r2_rule RHEL-06-000083 CCI-000366 MEDIUM The system must not accept IPv4 source-routed packets on any interface. Accepting source-routed packets in the IPv4 protocol has few legitimate uses. It should be disabled unless it is absolutely required.
SV-50325r2_rule RHEL-06-000084 CCI-000366 MEDIUM The system must not accept ICMPv4 redirect packets on any interface. Accepting ICMP redirects has few legitimate uses. It should be disabled unless it is absolutely required.
SV-50326r4_rule RHEL-06-000169 CCI-000169 LOW The audit system must be configured to audit all attempts to alter system time through stime. Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time (such as sshd). All changes to the system time should be audited.
SV-50327r2_rule RHEL-06-000086 CCI-000366 MEDIUM The system must not accept ICMPv4 secure redirect packets on any interface. Accepting "secure" ICMP redirects (from those gateways listed as default gateways) has few legitimate uses. It should be disabled unless it is absolutely required.
SV-50328r3_rule RHEL-06-000171 CCI-000169 LOW The audit system must be configured to audit all attempts to alter system time through clock_settime. Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time (such as sshd). All changes to the system time should be audited.
SV-50329r2_rule RHEL-06-000088 CCI-000366 LOW The system must log Martian packets. The presence of "martian" packets (which have impossible addresses) as well as spoofed packets, source-routed packets, and redirects could be a sign of nefarious network activity. Logging these packets enables this activity to be detected.
SV-50330r2_rule RHEL-06-000089 CCI-000366 MEDIUM The system must not accept IPv4 source-routed packets by default. Accepting source-routed packets in the IPv4 protocol has few legitimate uses. It should be disabled unless it is absolutely required.
SV-50331r2_rule RHEL-06-000173 CCI-000169 LOW The audit system must be configured to audit all attempts to alter system time through /etc/localtime. Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time (such as sshd). All changes to the system time should be audited.
SV-50332r2_rule RHEL-06-000174 CCI-000018 LOW The operating system must automatically audit account creation. In addition to auditing new user and group accounts, these watches will alert the system administrator(s) to any modifications. Any unexpected users, groups, or modifications should be investigated for legitimacy.
SV-50333r2_rule RHEL-06-000090 CCI-000366 MEDIUM The system must not accept ICMPv4 secure redirect packets by default. Accepting "secure" ICMP redirects (from those gateways listed as default gateways) has few legitimate uses. It should be disabled unless it is absolutely required.
SV-50334r3_rule RHEL-06-000091 CCI-000366 LOW The system must ignore ICMPv4 redirect messages by default. This feature of the IPv4 protocol has few legitimate uses. It should be disabled unless it is absolutely required.
SV-50335r2_rule RHEL-06-000175 CCI-001403 LOW The operating system must automatically audit account modification. In addition to auditing new user and group accounts, these watches will alert the system administrator(s) to any modifications. Any unexpected users, groups, or modifications should be investigated for legitimacy.
SV-50336r2_rule RHEL-06-000092 CCI-000366 LOW The system must not respond to ICMPv4 sent to a broadcast address. Ignoring ICMP echo requests (pings) sent to broadcast or multicast addresses makes the system slightly more difficult to enumerate on the network.
SV-50337r2_rule RHEL-06-000176 CCI-001404 LOW The operating system must automatically audit account disabling actions. In addition to auditing new user and group accounts, these watches will alert the system administrator(s) to any modifications. Any unexpected users, groups, or modifications should be investigated for legitimacy.
SV-50338r2_rule RHEL-06-000093 CCI-000366 LOW The system must ignore ICMPv4 bogus error responses. Ignoring bogus ICMP error responses reduces log size, although some activity would not be logged.
SV-50339r2_rule RHEL-06-000177 CCI-001405 LOW The operating system must automatically audit account termination. In addition to auditing new user and group accounts, these watches will alert the system administrator(s) to any modifications. Any unexpected users, groups, or modifications should be investigated for legitimacy.
SV-50340r2_rule RHEL-06-000095 CCI-001095 MEDIUM The system must be configured to use TCP syncookies when experiencing a TCP SYN flood. A TCP SYN flood attack can cause a denial of service by filling a system's TCP connection table with connections in the SYN_RCVD state. Syncookies can be used to track a connection when a subsequent ACK is received, verifying the initiator is attempting a valid connection and is not a flood source. This feature is activated when a flood condition is detected, and enables the system to continue servicing valid connection requests.
SV-50341r4_rule RHEL-06-000182 CCI-000366 LOW The audit system must be configured to audit modifications to the systems network configuration. The network environment should not be modified by anything other than administrator action. Any change to network parameters should be audited.
SV-50342r2_rule RHEL-06-000183 CCI-000366 LOW The audit system must be configured to audit modifications to the systems Mandatory Access Control (MAC) configuration (SELinux). The system's mandatory access policy (SELinux) should not be arbitrarily changed by anything other than administrator action. All changes to MAC policy should be audited.
SV-50343r2_rule RHEL-06-000096 CCI-000366 MEDIUM The system must use a reverse-path filter for IPv4 network traffic when possible on all interfaces. Enabling reverse path filtering drops packets with source addresses that should not have been able to be received on the interface they were received on. It should not be used on systems which are routers for complicated networks, but is helpful for end hosts and routers serving small networks.
SV-50344r3_rule RHEL-06-000184 CCI-000172 LOW The audit system must be configured to audit all discretionary access control permission modifications using chmod. The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.
SV-50345r2_rule RHEL-06-000097 CCI-000366 MEDIUM The system must use a reverse-path filter for IPv4 network traffic when possible by default. Enabling reverse path filtering drops packets with source addresses that should not have been able to be received on the interface they were received on. It should not be used on systems which are routers for complicated networks, but is helpful for end hosts and routers serving small networks.
SV-50346r3_rule RHEL-06-000185 CCI-000172 LOW The audit system must be configured to audit all discretionary access control permission modifications using chown. The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.
SV-50348r3_rule RHEL-06-000186 CCI-000172 LOW The audit system must be configured to audit all discretionary access control permission modifications using fchmod. The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.
SV-50349r3_rule RHEL-06-000099 CCI-000366 MEDIUM The system must ignore ICMPv6 redirects by default. An illicit ICMP redirect message could result in a man-in-the-middle attack.
SV-50351r3_rule RHEL-06-000187 CCI-000172 LOW The audit system must be configured to audit all discretionary access control permission modifications using fchmodat. The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.
SV-50353r3_rule RHEL-06-000188 CCI-000172 LOW The audit system must be configured to audit all discretionary access control permission modifications using fchown. The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.
SV-50355r3_rule RHEL-06-000189 CCI-000172 LOW The audit system must be configured to audit all discretionary access control permission modifications using fchownat. The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.
SV-50356r2_rule RHEL-06-000113 CCI-001118 MEDIUM The system must employ a local IPv4 firewall. The "iptables" service provides the system's host-based firewalling capability for IPv4 and ICMP.
SV-50357r3_rule RHEL-06-000190 CCI-000172 LOW The audit system must be configured to audit all discretionary access control permission modifications using fremovexattr. The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.
SV-50358r3_rule RHEL-06-000191 CCI-000172 LOW The audit system must be configured to audit all discretionary access control permission modifications using fsetxattr. The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.
SV-50359r3_rule RHEL-06-000192 CCI-000172 LOW The audit system must be configured to audit all discretionary access control permission modifications using lchown. The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.
SV-50360r3_rule RHEL-06-000193 CCI-000172 LOW The audit system must be configured to audit all discretionary access control permission modifications using lremovexattr. The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.
SV-50362r3_rule RHEL-06-000194 CCI-000172 LOW The audit system must be configured to audit all discretionary access control permission modifications using lsetxattr. The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.
SV-50364r3_rule RHEL-06-000195 CCI-000172 LOW The audit system must be configured to audit all discretionary access control permission modifications using removexattr. The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.
SV-50366r3_rule RHEL-06-000196 CCI-000172 LOW The audit system must be configured to audit all discretionary access control permission modifications using setxattr. The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.
SV-50367r2_rule RHEL-06-000197 CCI-000172 LOW The audit system must be configured to audit failed attempts to access files and programs. Unsuccessful attempts to access files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise.
SV-50369r3_rule RHEL-06-000199 CCI-000172 LOW The audit system must be configured to audit successful file system mounts. The unauthorized exportation of data to external media could result in an information leak where classified information, Privacy Act information, and intellectual property could be lost. An audit trail should be created each time a filesystem is mounted to help identify and guard against information loss.
SV-50370r2_rule RHEL-06-000057 CCI-000192 LOW The system must require passwords to contain at least one uppercase alphabetic character. Requiring a minimum number of uppercase characters makes password guessing attacks more difficult by ensuring a larger search space.
SV-50371r2_rule RHEL-06-000058 CCI-001619 LOW The system must require passwords to contain at least one special character. Requiring a minimum number of special characters makes password guessing attacks more difficult by ensuring a larger search space.
SV-50372r3_rule RHEL-06-000059 CCI-000193 LOW The system must require passwords to contain at least one lower-case alphabetic character. Requiring a minimum number of lower-case characters makes password guessing attacks more difficult by ensuring a larger search space.
SV-50373r3_rule RHEL-06-000060 CCI-000195 LOW The system must require at least eight characters be changed between the old and new passwords during a password change. Requiring a minimum number of different characters during password changes ensures that newly changed passwords should not resemble previously compromised ones. Note that passwords which are changed on compromised systems will still be compromised, however.
SV-50374r4_rule RHEL-06-000061 CCI-000044 MEDIUM The system must disable accounts after three consecutive unsuccessful logon attempts. Locking out user accounts after a number of incorrect attempts prevents direct password guessing attacks.
SV-50375r4_rule RHEL-06-000062 CCI-000803 MEDIUM The system must use a FIPS 140-2 approved cryptographic hashing algorithm for generating account password hashes (system-auth). Using a stronger hashing algorithm makes password cracking attacks more difficult.
SV-50376r4_rule RHEL-06-000200 CCI-000172 LOW The audit system must be configured to audit user deletions of files and programs. Auditing file deletions will create an audit trail for files that are removed from the system. The audit trail could aid in system troubleshooting, as well as detecting malicious processes that attempt to delete log files to conceal their presence.
SV-50377r1_rule RHEL-06-000063 CCI-000803 MEDIUM The system must use a FIPS 140-2 approved cryptographic hashing algorithm for generating account password hashes (login.defs). Using a stronger hashing algorithm makes password cracking attacks more difficult.
SV-50378r1_rule RHEL-06-000064 CCI-000803 MEDIUM The system must use a FIPS 140-2 approved cryptographic hashing algorithm for generating account password hashes (libuser.conf). Using a stronger hashing algorithm makes password cracking attacks more difficult.
SV-50379r2_rule RHEL-06-000201 CCI-000172 LOW The audit system must be configured to audit changes to the /etc/sudoers file. The actions taken by system administrators should be audited to keep a record of what was executed on the system, as well as, for accountability purposes.
SV-50380r2_rule RHEL-06-000065 CCI-000366 MEDIUM The system boot loader configuration file(s) must be owned by root. Only root should be able to modify important boot parameters.
SV-50381r2_rule RHEL-06-000202 CCI-000172 MEDIUM The audit system must be configured to audit the loading and unloading of dynamic kernel modules. The addition/removal of kernel modules can be used to alter the behavior of the kernel and potentially introduce malicious code into kernel space. It is important to have an audit trail of modules that have been introduced into the kernel.
SV-50382r2_rule RHEL-06-000066 CCI-000366 MEDIUM The system boot loader configuration file(s) must be group-owned by root. The "root" group is a highly-privileged group. Furthermore, the group-owner of this file should not have any access privileges anyway.
SV-50383r2_rule RHEL-06-000203 CCI-000382 MEDIUM The xinetd service must be disabled if no network services utilizing it are enabled. The xinetd service provides a dedicated listener service for some programs, which is no longer necessary for commonly-used network services. Disabling it ensures that these uncommon services are not running, and also prevents attacks against xinetd itself.
SV-50384r4_rule RHEL-06-000067 CCI-000366 MEDIUM The system boot loader configuration file(s) must have mode 0600 or less permissive. Proper permissions ensure that only the root user can modify important boot parameters.
SV-50385r1_rule RHEL-06-000204 CCI-000382 LOW The xinetd service must be uninstalled if no network services utilizing it are enabled. Removing the "xinetd" package decreases the risk of the xinetd service's accidental (or intentional) activation.
SV-50386r4_rule RHEL-06-000068 CCI-000213 MEDIUM The system boot loader must require authentication. Password protection on the boot loader configuration ensures users with physical access cannot trivially alter important bootloader settings. These include which kernel to use, and whether to enter single-user mode.
SV-50387r1_rule RHEL-06-000069 CCI-000213 MEDIUM The system must require authentication upon booting into single-user and maintenance modes. This prevents attackers with physical access from trivially bypassing security on the machine and gaining root access. Such accesses are further prevented by configuring the bootloader password.
SV-50388r1_rule RHEL-06-000206 CCI-000381 HIGH The telnet-server package must not be installed. Removing the "telnet-server" package decreases the risk of the unencrypted telnet service's accidental (or intentional) activation. Mitigation: If the telnet-server package is configured to only allow encrypted sessions, such as with Kerberos or the use of encrypted network tunnels, the risk of exposing sensitive information is mitigated.
SV-50389r1_rule RHEL-06-000070 CCI-000213 MEDIUM The system must not permit interactive boot. Using interactive boot, the console user could disable auditing, firewalls, or other services, weakening system security.
SV-50390r2_rule RHEL-06-000211 CCI-000888 HIGH The telnet daemon must not be running. The telnet protocol uses unencrypted network communication, which means that data from the login session, including passwords and all other information transmitted during the session, can be stolen by eavesdroppers on the network. The telnet protocol is also subject to man-in-the-middle attacks. Mitigation: If an enabled telnet daemon is configured to only allow encrypted sessions, such as with Kerberos or the use of encrypted network tunnels, the risk of exposing sensitive information is mitigated.
SV-50391r1_rule RHEL-06-000071 CCI-000058 LOW The system must allow locking of the console screen in text mode. Installing "screen" ensures a console locking capability is available for users who may need to suspend console logins.
SV-50392r1_rule RHEL-06-000213 CCI-000381 HIGH The rsh-server package must not be installed. The "rsh-server" package provides several obsolete and insecure network services. Removing it decreases the risk of those services' accidental (or intentional) activation.
SV-50393r4_rule RHEL-06-000356 CCI-000047 MEDIUM The system must require administrator action to unlock an account locked by excessive failed login attempts. Locking out user accounts after a number of incorrect attempts prevents direct password guessing attacks. Ensuring that an administrator is involved in unlocking locked accounts draws appropriate attention to such situations.
SV-50395r2_rule RHEL-06-000214 CCI-000068 HIGH The rshd service must not be running. The rsh service uses unencrypted network communications, which means that data from the login session, including passwords and all other information transmitted during the session, can be stolen by eavesdroppers on the network.
SV-50399r2_rule RHEL-06-000216 CCI-000068 HIGH The rexecd service must not be running. The rexec service uses unencrypted network communications, which means that data from the login session, including passwords and all other information transmitted during the session, can be stolen by eavesdroppers on the network.
SV-50401r2_rule RHEL-06-000080 CCI-000366 MEDIUM The system must not send ICMPv4 redirects by default. Sending ICMP redirects permits the system to instruct other systems to update their routing information. The ability to send ICMP redirects is only appropriate for systems acting as routers.
SV-50402r2_rule RHEL-06-000081 CCI-000366 MEDIUM The system must not send ICMPv4 redirects from any interface. Sending ICMP redirects permits the system to instruct other systems to update their routing information. The ability to send ICMP redirects is only appropriate for systems acting as routers.
SV-50403r2_rule RHEL-06-000218 CCI-001436 HIGH The rlogind service must not be running. The rlogin service uses unencrypted network communications, which means that data from the login session, including passwords and all other information transmitted during the session, can be stolen by eavesdroppers on the network.
SV-50404r1_rule RHEL-06-000220 CCI-000381 MEDIUM The ypserv package must not be installed. Removing the "ypserv" package decreases the risk of the accidental (or intentional) activation of NIS or NIS+ services.
SV-50405r2_rule RHEL-06-000221 CCI-000382 MEDIUM The ypbind service must not be running. Disabling the "ypbind" service ensures the system is not acting as a client in a NIS or NIS+ domain.
SV-50406r2_rule RHEL-06-000224 CCI-000366 MEDIUM The cron service must be running. Due to its usage for maintenance and security-supporting tasks, enabling the cron daemon is essential.
SV-50407r3_rule RHEL-06-000222 CCI-000381 MEDIUM The tftp-server package must not be installed unless required. Removing the "tftp-server" package decreases the risk of the accidental (or intentional) activation of tftp services.
SV-50408r1_rule RHEL-06-000227 CCI-000774 HIGH The SSH daemon must be configured to use only the SSHv2 protocol. SSH protocol version 1 suffers from design flaws that result in security vulnerabilities and should not be used.
SV-50409r1_rule RHEL-06-000230 CCI-001133 LOW The SSH daemon must set a timeout interval on idle sessions. Causing idle users to be automatically logged out guards against compromises one system leading trivially to compromises on another.
SV-50411r1_rule RHEL-06-000231 CCI-000879 LOW The SSH daemon must set a timeout count on idle sessions. This ensures a user login will be terminated as soon as the "ClientAliveCountMax" is reached.
SV-50412r1_rule RHEL-06-000234 CCI-000766 MEDIUM The SSH daemon must ignore .rhosts files. SSH trust relationships mean a compromise on one host can allow an attacker to move trivially to other hosts.
SV-50413r1_rule RHEL-06-000236 CCI-000766 MEDIUM The SSH daemon must not allow host-based authentication. SSH trust relationships mean a compromise on one host can allow an attacker to move trivially to other hosts.
SV-50414r1_rule RHEL-06-000237 CCI-000770 MEDIUM The system must not permit root logins using remote access programs such as ssh. Permitting direct root login reduces auditable information about who ran privileged commands on the system and also allows direct attack attempts on root's password.
SV-50415r1_rule RHEL-06-000239 CCI-000766 HIGH The SSH daemon must not allow authentication using an empty password. Configuring this setting for the SSH daemon provides additional assurance that remote login via SSH will require a password, even in the event of misconfiguration elsewhere.
SV-50416r1_rule RHEL-06-000240 CCI-000048 MEDIUM The SSH daemon must be configured with the Department of Defense (DoD) login banner. The warning message reinforces policy awareness during the logon process and facilitates possible legal action against attackers. Alternatively, systems whose ownership should not be obvious should ensure usage of a banner that does not provide easy attribution.
SV-50417r1_rule RHEL-06-000241 CCI-001414 LOW The SSH daemon must not permit user environment settings. SSH environment options potentially allow users to bypass access restriction in some configurations.
SV-50419r2_rule RHEL-06-000246 CCI-000366 LOW The avahi service must be disabled. Because the Avahi daemon service keeps an open network port, it is subject to network attacks. Its functionality is convenient but is only appropriate if the local network can be trusted.
SV-50421r1_rule RHEL-06-000247 CCI-000160 MEDIUM The system clock must be synchronized continuously, or at least daily. Enabling the "ntpd" service ensures that the "ntpd" service will be running and that the system will synchronize its time to any servers specified. This is important whether the system is configured to be a client (and synchronize only its own clock) or it is also acting as an NTP server to other systems. Synchronizing time is essential for authentication services such as Kerberos, but it is also important for maintaining accurate logs and auditing possible security breaches.
SV-50422r1_rule RHEL-06-000248 CCI-000160 MEDIUM The system clock must be synchronized to an authoritative DoD time source. Synchronizing with an NTP server makes it possible to collate system logs from multiple sources or correlate computer events with real time events. Using a trusted NTP server provided by your organization is recommended.
SV-50423r2_rule RHEL-06-000249 CCI-000382 MEDIUM Mail relaying must be restricted. This ensures "postfix" accepts mail messages (such as cron job reports) from the local system only, and not from the network, which protects it from network attack.
SV-50428r2_rule RHEL-06-000256 CCI-000366 LOW The openldap-servers package must not be installed unless required. Unnecessary packages should not be installed to decrease the attack surface of the system.
SV-50430r3_rule RHEL-06-000257 CCI-000057 MEDIUM The graphical desktop environment must set the idle timeout to no more than 15 minutes. Setting the idle delay controls when the screensaver will start, and can be combined with screen locking to prevent access from passersby.
SV-50431r3_rule RHEL-06-000258 CCI-000057 MEDIUM The graphical desktop environment must automatically lock after 15 minutes of inactivity and the system must require user reauthentication to unlock the environment. Enabling idle activation of the screen saver ensures the screensaver will be activated after the idle delay. Applications requiring continuous, real-time screen display (such as network management products) require the login session does not have administrator rights and the display station is located in a controlled-access area.
SV-50434r1_rule RHEL-06-000160 CCI-000366 MEDIUM The system must set a maximum audit log file size. The total storage for audit log files must be large enough to retain log information over the period required. This is a function of the maximum log file size and the number of logs retained.
SV-50437r1_rule RHEL-06-000159 CCI-000366 MEDIUM The system must retain enough rotated audit logs to cover the required log retention period. The total storage for audit log files must be large enough to retain log information over the period required. This is a function of the maximum log file size and the number of logs retained.
SV-50439r3_rule RHEL-06-000259 CCI-000057 MEDIUM The graphical desktop environment must have automatic lock enabled. Enabling the activation of the screen lock after an idle period ensures password entry will be required in order to access the system, preventing access by passersby.
SV-50440r3_rule RHEL-06-000260 CCI-000060 LOW The system must display a publicly-viewable pattern during a graphical desktop environment session lock. Setting the screensaver mode to blank-only conceals the contents of the display from passersby.
SV-50441r2_rule RHEL-06-000261 CCI-000382 LOW The Automatic Bug Reporting Tool (abrtd) service must not be running. Mishandling crash data could expose sensitive information about vulnerabilities in software executing on the local machine, as well as sensitive information from within a process's address space or registers.
SV-50442r3_rule RHEL-06-000262 CCI-000382 LOW The atd service must be disabled. The "atd" service could be used by an unsophisticated insider to carry out activities outside of a normal login session, which could complicate accountability. Furthermore, the need to schedule tasks with "at" or "batch" is not common.
SV-50443r1_rule RHEL-06-000346 CCI-000366 LOW The system default umask for daemons must be 027 or 022. The umask influences the permissions assigned to files created by a process at run time. An unnecessarily permissive umask could result in files being created with insecure permissions.
SV-50445r2_rule RHEL-06-000265 CCI-000382 LOW The ntpdate service must not be running. The "ntpdate" service may only be suitable for systems which are rebooted frequently enough that clock drift does not cause problems between reboots. In any event, the functionality of the ntpdate service is now available in the ntpd program and should be considered deprecated.
SV-50446r1_rule RHEL-06-000345 CCI-000366 LOW The system default umask in /etc/login.defs must be 077. The umask value influences the permissions assigned to files when they are created. A misconfigured umask value could result in files with excessive permissions that can be read and/or written to by unauthorized users.
SV-50447r2_rule RHEL-06-000266 CCI-000382 LOW The oddjobd service must not be running. The "oddjobd" service may provide necessary functionality in some environments but it can be disabled if it is not needed. Execution of tasks by privileged programs, on behalf of unprivileged ones, has traditionally been a source of privilege escalation security issues.
SV-50448r1_rule RHEL-06-000344 CCI-000366 LOW The system default umask in /etc/profile must be 077. The umask value influences the permissions assigned to files when they are created. A misconfigured umask value could result in files with excessive permissions that can be read and/or written to by unauthorized users.
SV-50449r2_rule RHEL-06-000267 CCI-000382 LOW The qpidd service must not be running. The qpidd service is automatically installed when the "base" package selection is selected during installation. The qpidd service listens for network connections which increases the attack surface of the system. If the system is not intended to receive AMQP traffic then the "qpidd" service is not needed and should be disabled or removed.
SV-50450r1_rule RHEL-06-000343 CCI-000366 LOW The system default umask for the csh shell must be 077. The umask value influences the permissions assigned to files when they are created. A misconfigured umask value could result in files with excessive permissions that can be read and/or written to by unauthorized users.
SV-50451r2_rule RHEL-06-000268 CCI-000382 LOW The rdisc service must not be running. General-purpose systems typically have their network and routing information configured statically by a system administrator. Workstations or some special-purpose systems often use DHCP (instead of IRDP) to retrieve dynamic network configuration information.
SV-50452r1_rule RHEL-06-000342 CCI-000366 LOW The system default umask for the bash shell must be 077. The umask value influences the permissions assigned to files when they are created. A misconfigured umask value could result in files with excessive permissions that can be read and/or written to by unauthorized users.
SV-50457r1_rule RHEL-06-000272 CCI-000366 LOW The system must use SMB client signing for connecting to samba servers using smbclient. Packet signing can prevent man-in-the-middle attacks which modify SMB packets in transit.
SV-50459r6_rule RHEL-06-000274 CCI-000200 MEDIUM The system must prohibit the reuse of passwords within five iterations. Preventing reuse of previous passwords helps ensure that a compromised password is not reused by a user.
SV-50469r4_rule RHEL-06-000286 CCI-000366 HIGH The x86 Ctrl-Alt-Delete key sequence must be disabled. A locally logged-in user who presses Ctrl-Alt-Delete, when at the console, can reboot the system. If accidentally pressed, as could happen in the case of mixed OS environment, this can create the risk of short-term loss of availability of systems due to unintentional reboot. In the GNOME graphical environment, risk of unintentional reboot from the Ctrl-Alt-Delete sequence is reduced because the user will be prompted before any action is taken.
SV-50470r1_rule RHEL-06-000287 CCI-000366 LOW The postfix service must be enabled for mail delivery. Local mail delivery is essential to some system maintenance and notification tasks.
SV-50472r1_rule RHEL-06-000288 CCI-000366 MEDIUM The sendmail package must be removed. The sendmail software was not developed with security in mind and its design prevents it from being effectively contained by SELinux. Postfix should be used instead.
SV-50473r2_rule RHEL-06-000289 CCI-000382 LOW The netconsole service must be disabled unless required. The "netconsole" service is not necessary unless there is a need to debug kernel panics, which is not common.
SV-50475r1_rule RHEL-06-000290 CCI-001436 MEDIUM X Windows must not be enabled unless required. Unnecessary services should be disabled to decrease the attack surface of the system.
SV-50476r2_rule RHEL-06-000308 CCI-000366 LOW Process core dumps must be disabled unless needed. A core dump includes a memory image taken at the time the operating system terminates an application. The memory image could contain sensitive data and is generally useful only for developers trying to debug problems.
SV-50477r2_rule RHEL-06-000291 CCI-000366 LOW The xorg-x11-server-common (X Windows) package must not be installed, unless required. Unnecessary packages should not be installed to decrease the attack surface of the system.
SV-50478r1_rule RHEL-06-000309 CCI-000764 HIGH The NFS server must not have the insecure file locking option enabled. Allowing insecure file locking could allow for sensitive data to be viewed or edited by an unauthorized user.
SV-50480r3_rule RHEL-06-000292 CCI-000366 MEDIUM The DHCP client must be disabled if not needed. DHCP relies on trusting the local network. If the local network is not trusted, then it should not be used. However, the automatic configuration provided by DHCP is commonly used and the alternative, manual configuration, presents an unacceptable burden in many circumstances.
SV-50481r1_rule RHEL-06-000313 CCI-000139 MEDIUM The audit system must identify staff members to receive notifications of audit log storage volume capacity issues. Email sent to the root account is typically aliased to the administrators of the system, who can take appropriate action.
SV-50485r2_rule RHEL-06-000319 CCI-000054 LOW The system must limit users to 10 simultaneous system logins, or a site-defined number, in accordance with operational requirements. Limiting simultaneous user logins can insulate the system from denial of service problems caused by excessive logins. Automated login processes operating improperly or maliciously may result in an exceptional number of simultaneous login sessions.
SV-50488r3_rule RHEL-06-000321 CCI-001130 LOW The system must provide VPN connectivity for communications over untrusted networks. Providing the ability for remote users or systems to initiate a secure VPN connection protects information when it is transmitted over a wide area network.
SV-50489r3_rule RHEL-06-000324 CCI-000050 MEDIUM A login banner must be displayed immediately prior to, or as part of, graphical desktop environment login prompts. An appropriate warning message reinforces policy awareness during the logon process and facilitates possible legal action against attackers.
SV-50492r2_rule RHEL-06-000331 CCI-000085 MEDIUM The Bluetooth service must be disabled. Disabling the "bluetooth" service prevents the system from attempting connections to Bluetooth devices, which entails some security risk. Nevertheless, variation in this risk decision may be expected due to the utility of Bluetooth connectivity and its limited range.
SV-50493r1_rule RHEL-06-000334 CCI-000017 LOW Accounts must be locked upon 35 days of inactivity. Disabling inactive accounts ensures that accounts which may not have been responsibly removed are not available to attackers who may have compromised their credentials.
SV-50494r4_rule RHEL-06-000299 CCI-000366 LOW The system must require passwords to contain no more than three consecutive repeating characters. Passwords with excessive repeating characters may be more vulnerable to password-guessing attacks.
SV-50495r1_rule RHEL-06-000335 CCI-000795 LOW The operating system must manage information system identifiers for users and devices by disabling the user identifier after an organization defined time period of inactivity. Disabling inactive accounts ensures that accounts which may not have been responsibly removed are not available to attackers who may have compromised their credentials.
SV-50502r2_rule RHEL-06-000338 CCI-000366 HIGH The TFTP daemon must operate in secure mode which provides access only to a single directory on the host file system. Using the "-s" option causes the TFTP service to only serve files from the given directory. Serving files from an intentionally specified directory reduces the risk of sharing files which should remain private.
SV-65547r2_rule RHEL-06-000017 CCI-000366 MEDIUM The system must use a Linux Security Module at boot time. Disabling a major host protection feature, such as SELinux, at boot time prevents it from confining system services at boot time. Further, it increases the chances that it will remain off during system operation.
SV-65573r1_rule RHEL-06-000020 CCI-000366 MEDIUM The system must use a Linux Security Module configured to enforce limits on system services. Setting the SELinux state to enforcing ensures SELinux is able to confine potentially compromised processes to the security policy, which is designed to prevent them from causing damage to the system or further elevating their privileges.
SV-65579r1_rule RHEL-06-000023 CCI-000366 LOW The system must use a Linux Security Module configured to limit the privileges of system services. Setting the SELinux policy to "targeted" or a more specialized policy ensures the system will confine processes that are likely to be targeted for exploitation, such as network or system services.
SV-66089r1_rule RHEL-06-000372 CCI-000366 MEDIUM The operating system, upon successful logon/access, must display to the user the number of unsuccessful logon/access attempts since the last successful logon/access. Users need to be aware of activity that occurs regarding their account. Providing users with information regarding the number of unsuccessful attempts that were made to login to their account allows the user to determine if any unauthorized activity has occurred and gives them an opportunity to notify administrators.
SV-68627r3_rule RHEL-06-000163 CCI-000366 MEDIUM The audit system must switch the system to single-user mode when available audit storage volume becomes dangerously low. Administrators should be made aware of an inability to record audit records. If a separate partition or logical volume of adequate size is used, running low on space for audit records should never occur.
SV-96155r1_rule RHEL-06-000166 CCI-000169 LOW The audit system must be configured to audit all attempts to alter system time through adjtimex. Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time (such as sshd). All changes to the system time should be audited.
SV-96159r1_rule RHEL-06-000530 CCI-001764 LOW The Red Hat Enterprise Linux operating system must mount /dev/shm with the nodev option. The "nodev" mount option causes the system to not interpret character or block special devices. Executing character or block special devices from untrusted file systems increases the opportunity for unprivileged users to attain unauthorized administrative access.
SV-96161r1_rule RHEL-06-000531 CCI-001764 LOW The Red Hat Enterprise Linux operating system must mount /dev/shm with the nosuid option. The "nosuid" mount option causes the system to not execute "setuid" and "setgid" files with owner privileges. This option must be used for mounting any file system not containing approved "setuid" and "setguid" files. Executing files from untrusted file systems increases the opportunity for unprivileged users to attain unauthorized administrative access.
SV-96163r1_rule RHEL-06-000532 CCI-001764 LOW The Red Hat Enterprise Linux operating system must mount /dev/shm with the noexec option. The "noexec" mount option causes the system to not execute binary files. This option must be used for mounting any file system not containing approved binary files as they may be incompatible. Executing files from untrusted file systems increases the opportunity for unprivileged users to attain unauthorized administrative access.