DoD Compliance · STIG

Microsoft Exchange 2016 Edge Transport Server Security Technical Implementation Guide

V2R1 · · 5.5 years ago · Released 23 Oct 2020 · 69 rules

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This Security Technical Implementation Guide is published as a tool to improve the security of Department of Defense (DoD) information systems. The requirements are derived from the National Institute of Standards and Technology (NIST) 800-53 and related documents. Comments or proposed revisions to this document should be sent via email to the following address: disa.stig_spt@mail.mil.

Digest of Updates vs. V1R5 · 24 Jul 2020 +69 −70

Comparison against the immediately-prior release (V1R5). Rule matching uses the Group Vuln ID. Content-change detection compares the rule’s description, check, and fix text after stripping inline markup — cosmetic-only edits aren’t flagged.

Added rules 69

V-221202 Medium Exchange must limit the Receive connector timeout.
V-221203 Medium Exchange servers must use approved DoD certificates.
V-221204 Medium Exchange must have accepted domains configured.
V-221205 Medium Exchange must have auto-forwarding of email to remote domains disabled or restricted.
V-221206 Medium Exchange external Receive connectors must be domain secure-enabled.
V-221207 Medium The Exchange email Diagnostic log level must be set to the lowest level.
V-221208 Medium Exchange Connectivity logging must be enabled.
V-221209 Medium Exchange Queue monitoring must be configured with threshold and action.
V-221210 Medium Exchange must not send Customer Experience reports to Microsoft.
V-221211 Medium Exchange Audit data must be protected against unauthorized access (read access).
V-221212 Medium Exchange Send Fatal Errors to Microsoft must be disabled.
V-221213 Medium Exchange audit data must be protected against unauthorized access for modification.
V-221214 Medium Exchange audit data must be protected against unauthorized access for deletion.
V-221215 Medium Exchange audit data must be on separate partitions.
V-221216 Medium The Exchange local machine policy must require signed scripts.
V-221217 Medium Exchange Internet-facing Send connectors must specify a Smart Host.
V-221218 Medium Exchange internal Send connectors must use domain security (mutual authentication Transport Layer Security).
V-221219 Medium Exchange Internet-facing Receive connectors must offer Transport Layer Security (TLS) before using basic authentication.
V-221220 Medium Exchange Outbound Connection Timeout must be 10 minutes or less.
V-221221 Medium Exchange Outbound Connection Limit per Domain Count must be controlled.
V-221222 Low Exchange Send connector connections count must be limited.
V-221223 Low Exchange message size restrictions must be controlled on Send connectors.
V-221224 Low Exchange Send connectors delivery retries must be controlled.
V-221225 Low Exchange Send connectors must be clearly named.
V-221226 Medium Exchange Receive connector Maximum Hop Count must be 60.
V-221227 Low Exchange Receive connectors must be clearly named.
V-221228 Low Exchange Receive connectors must control the number of recipients chunked on a single message.
V-221229 Medium Exchange Receive connectors must control the number of recipients per message.
V-221230 Low The Exchange Internet Receive connector connections count must be set to default.
V-221231 Low Exchange Message size restrictions must be controlled on Receive connectors.
V-221232 Medium Exchange messages with a blank sender field must be rejected.
V-221233 Medium Exchange messages with a blank sender field must be filtered.
V-221234 Medium Exchange filtered messages must be archived.
V-221235 Medium The Exchange Sender filter must block unaccepted domains.
V-221236 Medium Exchange nonexistent recipients must not be blocked.
V-221237 Medium The Exchange Sender Reputation filter must be enabled.
V-221238 Medium The Exchange Sender Reputation filter must identify the spam block level.
V-221239 Medium Exchange Attachment filtering must remove undesirable attachments by file type.
V-221240 Medium The Exchange Spam Evaluation filter must be enabled.
V-221241 Medium The Exchange Block List service provider must be identified.
V-221242 Medium Exchange messages with a malformed From address must be rejected.
V-221243 Medium The Exchange Recipient filter must be enabled.
V-221244 Medium The Exchange tarpitting interval must be set.
V-221245 Medium Exchange internal Receive connectors must not allow anonymous connections.
V-221246 Medium Exchange Simple Mail Transfer Protocol (SMTP) IP Allow List entries must be empty.
V-221247 Medium The Exchange Simple Mail Transfer Protocol (SMTP) IP Allow List Connection filter must be enabled.
V-221248 Medium The Exchange Simple Mail Transfer Protocol (SMTP) Sender filter must be enabled.
V-221249 Medium Exchange must have antispam filtering installed.
V-221250 Medium Exchange must have antispam filtering enabled.
V-221251 Medium Exchange must have antispam filtering configured.
V-221252 Medium Exchange Sender Identification Framework must be enabled.
V-221253 High Exchange must strip hyperlink email sources from non-.mil domains.
V-221254 Medium The Exchange application directory must be protected from unauthorized access.
V-221255 Medium The Exchange software baseline copy must exist.
V-221256 Medium Exchange services must be documented and unnecessary services must be removed or disabled.
V-221257 Medium Exchange software must be installed on a separate partition from the OS.
V-221258 Medium The Exchange SMTP automated banner response must not reveal server details.
V-221259 High Exchange must provide redundancy.
V-221260 Medium Exchange internal Send connectors must use an authentication level.
V-221261 High Exchange internal Receive connectors must require encryption.
V-221262 High Exchange internal Send connectors must require encryption.
V-221263 Medium Exchange must have the most current, approved service pack installed.
V-221264 Medium The application must configure malicious code protection mechanisms to perform periodic scans of the information system every seven days.
V-221265 Medium The application must configure malicious code protection mechanisms to perform periodic scans of the information system every seven days.
V-221266 Medium The application must be configured to block and quarantine malicious code upon detection, then send an immediate alert to appropriate individuals.
V-221267 Medium The application must be configured to block and quarantine malicious code upon detection, then send an immediate alert to appropriate individuals.
V-221268 Medium The application must update malicious code protection mechanisms whenever new releases are available in accordance with organizational configuration management policy and procedures.
V-221269 Medium The application must update malicious code protection mechanisms whenever new releases are available in accordance with organizational configuration management policy and procedures.
V-221270 Medium The applications built-in Malware Agent must be disabled.

Removed rules 70

V-80485 Medium Exchange must limit the Receive connector timeout.
V-80487 Medium Exchange servers must use approved DoD certificates.
V-80489 Medium Exchange must have accepted domains configured.
V-80491 Medium Exchange must have auto-forwarding of email to remote domains disabled or restricted.
V-80493 Medium Exchange external Receive connectors must be domain secure-enabled.
V-80495 Medium The Exchange email Diagnostic log level must be set to the lowest level.
V-80497 Medium Exchange Connectivity logging must be enabled.
V-80499 Medium Exchange Queue monitoring must be configured with threshold and action.
V-80501 Medium Exchange must not send Customer Experience reports to Microsoft.
V-80503 Medium Exchange Audit data must be protected against unauthorized access (read access).
V-80505 Medium Exchange Send Fatal Errors to Microsoft must be disabled.
V-80507 Medium Exchange audit data must be protected against unauthorized access for modification.
V-80509 Medium Exchange audit data must be protected against unauthorized access for deletion.
V-80511 Medium Exchange audit data must be on separate partitions.
V-80513 Medium The Exchange local machine policy must require signed scripts.
V-80515 Medium Exchange Internet-facing Send connectors must specify a Smart Host.
V-80517 Medium Exchange internal Send connectors must use domain security (mutual authentication Transport Layer Security).
V-80519 Medium Exchange Internet-facing Receive connectors must offer Transport Layer Security (TLS) before using basic authentication.
V-80521 Medium Exchange Outbound Connection Timeout must be 10 minutes or less.
V-80523 Medium Exchange Outbound Connection Limit per Domain Count must be controlled.
V-80525 Low Exchange Send connector connections count must be limited.
V-80527 Low Exchange message size restrictions must be controlled on Send connectors.
V-80529 Low Exchange Send connectors delivery retries must be controlled.
V-80531 Low Exchange Send connectors must be clearly named.
V-80533 Medium Exchange Receive connector Maximum Hop Count must be 60.
V-80535 Low Exchange Receive connectors must be clearly named.
V-80537 Low Exchange Receive connectors must control the number of recipients chunked on a single message.
V-80539 Medium Exchange Receive connectors must control the number of recipients per message.
V-80541 Low The Exchange Internet Receive connector connections count must be set to default.
V-80543 Low Exchange Message size restrictions must be controlled on Receive connectors.
V-80545 Medium Exchange messages with a blank sender field must be rejected.
V-80547 Medium Exchange messages with a blank sender field must be filtered.
V-80549 Medium Exchange filtered messages must be archived.
V-80551 Medium The Exchange Sender filter must block unaccepted domains.
V-80553 Medium Exchange nonexistent recipients must not be blocked.
V-80555 Medium The Exchange Sender Reputation filter must be enabled.
V-80557 Medium The Exchange Sender Reputation filter must identify the spam block level.
V-80559 Medium Exchange Attachment filtering must remove undesirable attachments by file type.
V-80561 Medium The Exchange Spam Evaluation filter must be enabled.
V-80563 Medium The Exchange Block List service provider must be identified.
V-80565 Medium Exchange messages with a malformed From address must be rejected.
V-80567 Medium The Exchange Recipient filter must be enabled.
V-80569 Medium The Exchange tarpitting interval must be set.
V-80571 Medium Exchange internal Receive connectors must not allow anonymous connections.
V-80573 Medium Exchange Simple Mail Transfer Protocol (SMTP) IP Allow List entries must be empty.
V-80575 Medium The Exchange Simple Mail Transfer Protocol (SMTP) IP Allow List Connection filter must be enabled.
V-80577 Medium The Exchange Simple Mail Transfer Protocol (SMTP) Sender filter must be enabled.
V-80579 Medium Exchange must have antispam filtering installed.
V-80581 Medium Exchange must have antispam filtering enabled.
V-80583 Medium Exchange must have antispam filtering configured.
V-80585 Medium Exchange Sender Identification Framework must be enabled.
V-80587 High Exchange must strip hyperlink email sources from non-.mil domains.
V-80589 Medium The Exchange application directory must be protected from unauthorized access.
V-80591 Medium The Exchange software baseline copy must exist.
V-80593 Medium Exchange services must be documented and unnecessary services must be removed or disabled.
V-80595 Medium Exchange software must be installed on a separate partition from the OS.
V-80597 Medium The Exchange SMTP automated banner response must not reveal server details.
V-80599 High Exchange must provide redundancy.
V-80601 Medium Exchange internal Send connectors must use an authentication level.
V-80603 High Exchange internal Send connectors must require encryption.
V-80605 Medium Exchange must have the most current, approved service pack installed.
V-80607 Medium The application must configure malicious code protection mechanisms to perform periodic scans of the information system every seven days.
V-80609 Medium The application must configure malicious code protection mechanisms to perform periodic scans of the information system every seven days.
V-80611 Medium The application must be configured to block and quarantine malicious code upon detection, then send an immediate alert to appropriate individuals.
V-80613 Medium The application must be configured to block and quarantine malicious code upon detection, then send an immediate alert to appropriate individuals.
V-80615 Medium The application must update malicious code protection mechanisms whenever new releases are available in accordance with organizational configuration management policy and procedures.
V-80617 Medium The application must update malicious code protection mechanisms whenever new releases are available in accordance with organizational configuration management policy and procedures.
V-80619 Medium The applications built-in Malware Agent must be disabled.
V-80621 Medium A DoD-approved third-party Exchange-aware malicious code protection application must be implemented.
V-80753 High Exchange internal Receive connectors must require encryption.

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Exchange must limit the Receive connector timeout.

AC-10 - Medium - CCI-000054 - V-221202 - SV-221202r508017_rule

RMF Control

AC-10

Severity

CCI

CCI-000054

Version

EX16-ED-000010

Vuln IDs

V-221202
V-80485

Rule IDs

SV-221202r508017_rule
SV-95195

Email system availability depends in part on best practices strategies for setting tuning. This configuration controls the number of idle minutes before the connection is dropped. It works in conjunction with the Maximum Inbound Connections Count setting. Connections, once established, may incur delays in message transfer. If the timeout period is too long, there is risk that connections may be maintained for unnecessarily long time periods, preventing new connections from being established.

Checks: C-22917r411732_chk

Review the Email Domain Security Plan (EDSP), or Organizations applicable documentation. Determine the connection Timeout value. Open the Exchange Management Shell and enter the following command: Get-ReceiveConnector | Select Name, Identity, ConnectionTimeout For each Receive connector, if the value of "ConnectionTimeout" is not set to "00:05:00", this is a finding. or If "ConnectionTimeout" is set to another value other than "00:05:00" and has signoff and risk acceptance in the EDSP, this is not a finding.

Fix: F-22906r411733_fix

Update the EDSP, or the applicable documentation. Open the Exchange Management Shell and enter the following command: Set-ReceiveConnector -Identity <'IdentityName'> -ConnectionTimeout 00:05:00 Note: The <IdentityName> value must be in single quotes. or The value as identified by the EDSP that has obtained a signoff with risk acceptance. Repeat the procedures for each Receive connector.

Exchange servers must use approved DoD certificates.

AC-3 - Medium - CCI-000213 - V-221203 - SV-221203r508017_rule

RMF Control

AC-3

Severity

CCI

CCI-000213

Version

EX16-ED-000020

Vuln IDs

V-221203
V-80487

Rule IDs

SV-221203r508017_rule
SV-95197

To mitigate the risk of unauthorized access to sensitive information by entities that have been issued certificates by DoD-approved PKIs, all DoD systems (e.g., networks, web servers, and web portals) must be properly configured to incorporate access control methods that do not rely solely on the possession of a certificate for access. Successful authentication must not automatically give an entity access to an asset or security boundary. Authorization procedures and controls must be implemented to ensure each authenticated entity also has a validated and current authorization. Authorization is the process of determining whether an entity, once authenticated, is permitted to access a specific asset. Information systems use access control policies and enforcement mechanisms to implement this requirement. Access control policies include identity-based policies, role-based policies, and attribute-based policies. Access enforcement mechanisms include access control lists, access control matrices, and cryptography. These policies and mechanisms must be employed by the application to control access between users (or processes acting on behalf of users) and objects (e.g., devices, files, records, processes, programs, and domains) in the information system. This requirement is applicable to access control enforcement applications (e.g., authentication servers) and other applications that perform information and system access control functions.

Checks: C-22918r411735_chk

Open the Exchange Management Shell and enter the following command: Get-ExchangeCertificate | Select CertificateDomains, issuer If the value of "CertificateDomains" does not indicate it is issued by the DoD, this is a finding.

Fix: F-22907r411736_fix

Remove the non-DoD certificate and import the correct DoD certificates.

Exchange must have accepted domains configured.

AC-4 - Medium - CCI-001368 - V-221204 - SV-221204r508017_rule

RMF Control

AC-4

Severity

CCI

CCI-001368

Version

EX16-ED-000030

Vuln IDs

V-221204
V-80489

Rule IDs

SV-221204r508017_rule
SV-95199

Exchange may be configured to accept email for multiple domain names. This setting identifies the domains for which the server will accept mail. This check verifies the email server is not accepting email for unauthorized domains.

Checks: C-22919r411738_chk

Review the Email Domain Security Plan (EDSP). Determine the Accepted Domain values. Open the Exchange Management Shell and enter the following command: Get-AcceptedDomain | Select Name, DomainName, Identity, Default If the value of "Default" is not set to "True", this is a finding. or If the "Default" value for "AcceptedDomains" is set to another value other than "True" and has signoff and risk acceptance in the EDSP, this is not a finding.

Fix: F-22908r411739_fix

Update the EDSP. Open the Exchange Management Shell and enter the following command: Set-AcceptedDomain -Identity <'IdentityName'> -MakeDefault $true Note: The <IdentityName> value must be in single quotes.

Exchange must have auto-forwarding of email to remote domains disabled or restricted.

AC-4 - Medium - CCI-001368 - V-221205 - SV-221205r508017_rule

RMF Control

AC-4

Severity

CCI

CCI-001368

Version

EX16-ED-000040

Vuln IDs

V-221205
V-80491

Rule IDs

SV-221205r508017_rule
SV-95201

Attackers can use automated messages to determine whether a user account is active, in the office, traveling, and so on. An attacker might use this information to conduct future attacks. Ensure Automatic Forwards to remote domains are disabled, except for enterprise email that must be restricted to forward-only to .mil and .gov. domains. Before enabling this setting, first configure a remote domain.

Checks: C-22920r411741_chk

Non-Enterprise Mail Check Content: Open the Exchange Management Shell and enter the following command: Get-RemoteDomain | Select Name, DomainName, Identity, AutoForwardEnabled If the value of "AutoForwardEnabled" is not set to "False", this is a finding. Enterprise Mail Check Content: Open the Exchange Management Shell and enter the following command: Get-RemoteDomain | Select Name, DomainName, Identity, AutoForwardEnabled If the value of “AutoForwardEnabled” is “True” and “DomainName” is not set to a “.mil” and/or “.gov” domain(s), this is a finding.

Fix: F-22909r411742_fix

For Non-Enterprise Mail Fix Text: Open the Exchange Management Shell and enter the following command: Set-RemoteDomain -Identity <'IdentityName'> -AutoForwardEnabled $false Note: The <IdentityName> value must be in single quotes. For Enterprise Mail Fix Text, enter the following commands: New-RemoteDomain -Name <NewDomainName> -DomainName <SMTP address space> Note: NewDomainName must be either a ".mil" or ".gov" domain. Set-RemoteDomain -Identity <'IdentityName'> -AutoForwardEnabled $true

Exchange external Receive connectors must be domain secure-enabled.

AC-4 - Medium - CCI-001368 - V-221206 - SV-221206r508017_rule

RMF Control

AC-4

Severity

CCI

CCI-001368

Version

EX16-ED-000050

Vuln IDs

V-221206
V-80493

Rule IDs

SV-221206r508017_rule
SV-95203

The Simple Mail Transfer Protocol (SMTP) connector is used by Exchange to send and receive messages from server to server. Several controls work together to provide security between internal servers. This setting controls the authentication method used for communications between servers. With this feature enabled, messages can be securely passed from a partner domain securely. The use of secure communication prevents eavesdroppers from reading or modifying communications between mail clients and servers. While sensitive message bodies should be encrypted by the sender at the client, requiring a secure connection from server to server adds protection by encrypting the sender and recipient information that cannot be encrypted by the sender. Individually, channel security and encryption can be compromised by attackers. Used together, email becomes a more difficult target, and security is heightened. Failure to enable this feature gives eavesdroppers an opportunity to read or modify messages between servers.

Checks: C-22921r411744_chk

Open the Exchange Management Shell and enter the following command: Get-ReceiveConnector | Select Name, Identity, DomainSecureEnabled For each receive connector, if the value of "DomainSecureEnabled" is not set to "True", this is a finding.

Fix: F-22910r411745_fix

Open the Exchange Management Shell and enter the following command: Set-ReceiveConnector -Identity <'IdentityName'> -DomainSecureEnabled $true Note: The <IdentityName> value must be in single quotes. Repeat the procedures for each receive connector.

The Exchange email Diagnostic log level must be set to the lowest level.

AU-12 - Medium - CCI-000169 - V-221207 - SV-221207r508017_rule

RMF Control

AU-12

Severity

CCI

CCI-000169

Version

EX16-ED-000060

Vuln IDs

V-221207
V-80495

Rule IDs

SV-221207r508017_rule
SV-95205

Log files help establish a history of activities and can be useful in detecting attack attempts or determining tuning adjustments to improve availability. Diagnostic logging, however, characteristically produces large volumes of data and requires care in managing the logs to prevent risk of disk capacity denial of service conditions. Exchange diagnostic logging is broken up into 29 main "services", each of which has anywhere from 2 to 26 "categories" of events to be monitored. Moreover, each category may be set to one of four levels of logging: Lowest, Low, CAT II, and High, depending on how much detail one desires. The higher the level of detail, the more disk space required to store the audit material. Diagnostic logging is intended to help administrators debug problems with their systems, not as a general-purpose auditing tool. Because the diagnostic logs collect a great deal of information, the log files may grow large very quickly. Diagnostic log levels may be raised for limited periods of time when attempting to debug relevant pieces of Exchange functionality. Once debugging has finished, diagnostic log levels should be reduced again.

Checks: C-22922r411747_chk

Open the Exchange Management Shell and enter the following command: Get-EventLogLevel If any "EventLogLevel" values returned are not set to "Lowest", this is a finding.

Fix: F-22911r411748_fix

Open the Exchange Management Shell and enter the following command: Set-EventLogLevel -Identity <'IdentityName\EventlogName'> -Level Lowest Note: The <IdentityName\EventlogName> value must be in single quotes.

Exchange Connectivity logging must be enabled.

AU-12 - Medium - CCI-000169 - V-221208 - SV-221208r508017_rule

RMF Control

AU-12

Severity

CCI

CCI-000169

Version

EX16-ED-000070

Vuln IDs

V-221208
V-80497

Rule IDs

SV-221208r508017_rule
SV-95207

A connectivity log is a record of the SMTP connection activity of the outbound message delivery queues to the destination mailbox server, smart host, or domain. Connectivity logging is available on Hub Transport servers and Edge Transport servers. By default, connectivity logging is disabled. If events are not recorded, it may be difficult or impossible to determine the root cause of system problems or the unauthorized activities of malicious users. Note: Transport configuration settings apply to the organization/global level of the Exchange SMTP path. By checking and setting them at the Hub server, the setting will apply to both Hub and Edge roles.

Checks: C-22923r411750_chk

Open the Exchange Management Shell and enter the following command: Get-TransportService | Select Name, Identity, ConnectivityLogEnabled If the value of "ConnectivityLogEnabled" is not set to "True", this is a finding.

Fix: F-22912r411751_fix

Open the Exchange Management Shell and enter the following command: Set-TransportService -Identity <'IdentityName'> -ConnectivityLogEnabled $true Note: The <IdentityName> value must be in single quotes.

Exchange Queue monitoring must be configured with threshold and action.

AU-6 - Medium - CCI-000154 - V-221209 - SV-221209r508017_rule

RMF Control

AU-6

Severity

CCI

CCI-000154

Version

EX16-ED-000080

Vuln IDs

V-221209
V-80499

Rule IDs

SV-221209r508017_rule
SV-95209

Monitors are automated "process watchers" that respond to performance changes and can be useful in detecting outages and alerting administrators where attention is needed. Exchange has built-in monitors that enable the administrator to generate alerts if thresholds are reached, better enabling them to react in a timely fashion. This field offers choices of alerts when a "warning" or "critical" threshold is reached on the SMTP queue. A good rule of thumb (default) is to issue warnings when SMTP queue growth exceeds 10 minutes and critical messages when it exceeds 20 minutes, which should only exist occasionally. Frequent alerts against this counter may indicate a network or other issue (such as inbound SPAMMER traffic) that directly impacts email delivery. Notification choices include email alert to an email-enabled account (e.g., an email Administrator) or invoke a script to take other action (e.g., to add an Event to the Microsoft Application Event Log, where external monitors might detect it).

Checks: C-22924r411753_chk

Note: If a third-party application is performing monitoring functions, the reviewer should verify the application is monitoring correctly and mark the vulnerability NA. Open the Exchange Management Shell and enter the following command: perfmon In the left pane, navigate to Performance >> Data Collector Sets >> User Defined. If no sets are defined or queues are not being monitored, this is a finding.

Fix: F-22913r411754_fix

Open the Exchange Management Shell and enter the following command: perfmon In the left pane, navigate to Performance >> Data Collector Sets >> User Defined. In left pane, right-click on User Defined >> New >> Data Collector Set and configure the system to use the data collection set for monitoring the queues.

Exchange must not send Customer Experience reports to Microsoft.

CM-7 - Medium - CCI-000381 - V-221210 - SV-221210r508017_rule

RMF Control

CM-7

Severity

CCI

CCI-000381

Version

EX16-ED-000090

Vuln IDs

V-221210
V-80501

Rule IDs

SV-221210r508017_rule
SV-95211

It is detrimental for applications to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Applications are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). Examples of non-essential capabilities include, but are not limited to, advertising software or browser plug-ins not related to requirements or providing a wide array of functionality not required for every mission, but cannot be disabled. All system errors in Exchange will result in outbound traffic that may be identified by an eavesdropper. For this reason, the "Report Fatal Errors to Microsoft" feature must be disabled.

Checks: C-22925r411756_chk

Open the Exchange Management Shell and enter the following command: Get-OrganizationConfig | Select Name, Identity, CustomerFeedbackEnabled If the value for "CustomerFeedbackEnabled" is not set to "False", this is a finding.

Fix: F-22914r411757_fix

Open the Exchange Management Shell and enter the following command: Set-OrganizationConfig -CustomerFeedbackEnabled $false

Exchange Audit data must be protected against unauthorized access (read access).

AU-9 - Medium - CCI-000162 - V-221211 - SV-221211r508017_rule

RMF Control

AU-9

Severity

CCI

CCI-000162

Version

EX16-ED-000100

Vuln IDs

V-221211
V-80503

Rule IDs

SV-221211r508017_rule
SV-95213

Log files help establish a history of activities and can be useful in detecting attack attempts or determining tuning adjustments to improve availability. Audit log content must always be considered sensitive and in need of protection. Audit data available for modification by a malicious user can be altered to conceal malicious activity. Audit data might also provide a means for the malicious user to plan unauthorized activities that exploit weaknesses. The contents of audit logs are protected against unauthorized access, modification, or deletion. Only authorized auditors and the audit functions should be granted read and write access to audit log data.

Checks: C-22926r411759_chk

Review the Email Domain Security Plan (EDSP). Determine the authorized groups or users that should have read access to the audit data. If any group or user has read access to the audit data that is not documented in the EDSP, this is a finding.

Fix: F-22915r411760_fix

Update the EDSP to reflect the authorized groups or users that should have read access to the audit data. Restrict any unauthorized groups' or users' read access to the audit logs.

Exchange Send Fatal Errors to Microsoft must be disabled.

CM-7 - Medium - CCI-000381 - V-221212 - SV-221212r508017_rule

RMF Control

CM-7

Severity

CCI

CCI-000381

Version

EX16-ED-000110

Vuln IDs

V-221212
V-80505

Rule IDs

SV-221212r508017_rule
SV-95215

It is detrimental for applications to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Applications are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). Examples of non-essential capabilities include, but are not limited to, advertising software or browser plug-ins not related to requirements or providing a wide array of functionality not required for every mission, but cannot be disabled. Customer Experience reports in Exchange will result in outbound traffic that may be identified by an eavesdropper. For this reason, the Customer Experience reports to Microsoft must not be sent.

Checks: C-22927r411762_chk

Open the Exchange Management Shell and enter the following command: Get-ExchangeServer –status | Select Name, Identity, ErrorReportingEnabled For each exchange server, if the value of "ErrorReportingEnabled" is not set to "False", this is a finding.

Fix: F-22916r411763_fix

Open the Exchange Management Shell and enter the following command: Set-ExchangeServer -Identity <'IdentityName'> -ErrorReportingEnabled $false Note: The <IdentityName> value must be in single quotes. Repeat the procedure for each Identity.

Exchange audit data must be protected against unauthorized access for modification.

AU-9 - Medium - CCI-000163 - V-221213 - SV-221213r508017_rule

RMF Control

AU-9

Severity

CCI

CCI-000163

Version

EX16-ED-000120

Vuln IDs

V-221213
V-80507

Rule IDs

SV-221213r508017_rule
SV-95217

Checks: C-22928r411765_chk

Review the Email Domain Security Plan (EDSP). Determine the authorized groups or users that should have modify permissions to the audit data. If any group or user has modify permissions for the audit data that is not documented in the EDSP, this is a finding.

Fix: F-22917r411766_fix

Update the EDSP to reflect the authorized groups or users that should have modify permissions to the audit data. Restrict any unauthorized groups' or users' modify permissions for the audit logs.

Exchange audit data must be protected against unauthorized access for deletion.

AU-9 - Medium - CCI-000164 - V-221214 - SV-221214r508017_rule

RMF Control

AU-9

Severity

CCI

CCI-000164

Version

EX16-ED-000130

Vuln IDs

V-221214
V-80509

Rule IDs

SV-221214r508017_rule
SV-95219

Checks: C-22929r411768_chk

Review the Email Domain Security Plan (EDSP). Determine the authorized groups or users that should have delete permissions for the audit data. If any group or user has delete permissions for the audit data that is not documented in the EDSP, this is a finding.

Fix: F-22918r411769_fix

Update the EDSP to reflect the authorized groups or users that should have delete permissions for the audit data. Restrict any unauthorized groups' or users' delete permissions for the audit logs.

Exchange audit data must be on separate partitions.

AU-9 - Medium - CCI-001348 - V-221215 - SV-221215r508017_rule

RMF Control

AU-9

Severity

CCI

CCI-001348

Version

EX16-ED-000140

Vuln IDs

V-221215
V-80511

Rule IDs

SV-221215r508017_rule
SV-95221

Log files help establish a history of activities and can be useful in detecting attack attempts or determining tuning adjustments to improve availability. Audit log content must always be considered sensitive and in need of protection. Successful exploit of an application server vulnerability may well be logged by monitoring or audit processes when it occurs. Writing log and audit data to a separate partition where separate security contexts protect them may offer the ability to protect this information from being modified or removed by the exploit mechanism.

Checks: C-22930r411771_chk

Review the Email Domain Security Plan (EDSP). Determine the audit logs' assigned partition. Note: By default, the logs are located on the application partition in \Program Files\Microsoft\Exchange Server\V15\Logging\. If the log files are not on a separate partition from the application, this is a finding.

Fix: F-22919r411772_fix

Update the EDSP. Configure the audit log location to be on a partition drive separate from the application.

The Exchange local machine policy must require signed scripts.

CM-5 - Medium - CCI-001749 - V-221216 - SV-221216r508017_rule

RMF Control

CM-5

Severity

CCI

CCI-001749

Version

EX16-ED-000150

Vuln IDs

V-221216
V-80513

Rule IDs

SV-221216r508017_rule
SV-95223

Scripts, especially those downloaded from untrusted locations, often provide a way for attackers to infiltrate a system. By setting machine policy to prevent unauthorized script executions, unanticipated system impacts can be avoided.

Checks: C-22931r411774_chk

Open the Exchange Management Shell and enter the following command: Get-ExecutionPolicy If the value returned is not "RemoteSigned", this is a finding.

Fix: F-22920r411775_fix

Open the Exchange Management Shell and enter the following command: Set-ExecutionPolicy RemoteSigned

Exchange Internet-facing Send connectors must specify a Smart Host.

SC-20 - Medium - CCI-001178 - V-221217 - SV-221217r508017_rule

RMF Control

SC-20

Severity

CCI

CCI-001178

Version

EX16-ED-000160

Vuln IDs

V-221217
V-80515

Rule IDs

SV-221217r508017_rule
SV-95225

When identifying a "Smart Host" for the email environment, a logical Send connector is the preferred method. A Smart Host acts as an Internet-facing concentrator for other email servers. Appropriate hardening can be applied to the Smart Host, rather than at multiple locations throughout the enterprise. Failure to identify a Smart Host could default to each email server performing its own lookups (potentially through protective firewalls). Exchange servers should not be Internet facing and should therefore not perform any Smart Host functions. When the Exchange servers are Internet facing, they must be configured to identify the Internet-facing server that is performing the Smart Host function.

Checks: C-22932r411777_chk

Review the Email Domain Security Plan (EDSP). Determine the Internet-facing connectors. Open the Exchange Management Shell and enter the following command: Get-SendConnector | Select Name, Identity, SmartHosts, DNSRoutingEnabled For each send connector, if the value of "SmartHosts" does not return the Smart Host IP Address and the value for "DNSRoutingEnabled" is not set to "False", this is a finding.

Fix: F-22921r411778_fix

Open the Exchange Management Shell and enter the following command: Set-SendConnector <'IdentityName'> -SmartHosts <'IP Address of Smart Host'> -DNSRoutingEnabled $false Note: The <IdentityName> value must be in single quotes. Repeat the procedures for each send connector.

Exchange internal Send connectors must use domain security (mutual authentication Transport Layer Security).

SC-23 - Medium - CCI-001184 - V-221218 - SV-221218r508017_rule

RMF Control

SC-23

Severity

CCI

CCI-001184

Version

EX16-ED-000170

Vuln IDs

V-221218
V-80517

Rule IDs

SV-221218r508017_rule
SV-95227

The Simple Mail Transfer Protocol (SMTP) connector is used by Exchange to send and receive messages from server to server. Several controls work together to provide security between internal servers. This setting controls the authentication method used for communications between servers. With this feature enabled, only servers capable of supporting domain authentication will be able to send and receive mail within the domain. The use of secure communication prevents eavesdroppers from reading or modifying communications between mail clients and servers. While sensitive message bodies should be encrypted by the sender at the client, requiring a secure connection from server to server adds protection by encrypting the sender and recipient information that cannot be encrypted by the sender. Individually, channel security and encryption can be compromised by attackers. Used together, email becomes a more difficult target, and security is heightened. Failure to enable this feature gives eavesdroppers an opportunity to read or modify messages between servers.

Checks: C-22933r411780_chk

Open the Exchange Management Shell and enter the following command: Get-SendConnector | Select Name, Identity, DomainSecureEnabled For each send connector, if the value of "DomainSecureEnabled" is not set to "True", this is a finding. If the "TlsAuthLevel" parameter is set to "DomainValidation" then the "TlsDomain" parameter is required if "DNSRoutingEnabled" parameter is set to "$false". The "DNSRoutingEnabled" parameter must be "$true" If the value of "DomainSecureEnabled" is "$true".

Fix: F-22922r411781_fix

Open the Exchange Management Shell and enter the following command: Set-SendConnector <'IdentityName'> -DomainSecureEnabled $true Note: The <IdentityName> value must be in single quotes. Repeat the procedures for each send connector.

Exchange Internet-facing Receive connectors must offer Transport Layer Security (TLS) before using basic authentication.

SC-23 - Medium - CCI-001184 - V-221219 - SV-221219r508017_rule

RMF Control

SC-23

Severity

CCI

CCI-001184

Version

EX16-ED-000180

Vuln IDs

V-221219
V-80519

Rule IDs

SV-221219r508017_rule
SV-95229

Sending unencrypted email over the Internet increases the risk that messages can be intercepted or altered. TLS is designed to protect confidentiality and data integrity by encrypting email messages between servers and thereby reducing the risk of eavesdropping, interception, and alteration. This setting forces Exchange to offer TLS before using basic authentication.

Checks: C-22934r411783_chk

Open the Exchange Management Shell and enter the following command: Get-ReceiveConnector | Select Name, Identity, AuthMechanism For each receive connector, if the value of "AuthMechanism" is not set to "Tls, BasicAuth, BasicAuthRequireTLS", this is a finding.

Fix: F-22923r411784_fix

Open the Exchange Management Shell and enter the following command: Set-ReceiveConnector -Identity <'IdentityName'> -AuthMechanism 'Tls, BasicAuth, BasicAuthRequireTLS' Note: The <IdentityName> value must be in single quotes. Example only for the Identity: <ServerName>\Frontend <ServerName> Repeat the procedure for each receive connector.

Exchange Outbound Connection Timeout must be 10 minutes or less.

SC-5 - Medium - CCI-001095 - V-221220 - SV-221220r508017_rule

RMF Control

SC-5

Severity

CCI

CCI-001095

Version

EX16-ED-000190

Vuln IDs

V-221220
V-80521

Rule IDs

SV-221220r508017_rule
SV-95231

Email system availability depends in part on best practice strategies for setting tuning configurations. This configuration controls the number of idle minutes before the connection is dropped. It works in conjunction with the Maximum Outbound Connections Count setting. Connections, once established, may incur delays in message transfer. The default of 10 minutes is a reasonable window in which to resume activities without maintaining idle connections for excessive intervals. If the timeout period is too long, idle connections may be maintained for unnecessarily long time periods, preventing new connections from being established. Sluggish connectivity increases the risk of lost data. A value of 10 or less is optimal.

Checks: C-22935r411786_chk

Review the Email Domain Security Plan (EDSP). Determine the Connection Timeout value. Open the Exchange Management Shell and enter the following command: Get-SendConnector | Select Name, Identity, ConnectionInactivityTimeOut For each send connector, if the value of "ConnectionInactivityTimeOut" is not set to "00:10:00", this is a finding. or If "ConnectionInactivityTimeOut" is set to other than "00:10:00" and has signoff and risk acceptance in the EDSP, this is not a finding.

Fix: F-22924r411787_fix

Update the EDSP to reflect the Connection Timeout value. Open the Exchange Management Shell and enter the following command: Set-SendConnector -Identity <'IdentityName'> -ConnectionInactivityTimeOut 00:10:00 Note: The <IdentityName> value must be in single quotes. or The value as identified by the EDSP that has obtained a signoff with risk acceptance. Repeat the procedure for each send connector.

Exchange Outbound Connection Limit per Domain Count must be controlled.

SC-5 - Medium - CCI-001095 - V-221221 - SV-221221r508017_rule

RMF Control

SC-5

Severity

CCI

CCI-001095

Version

EX16-ED-000200

Vuln IDs

V-221221
V-80523

Rule IDs

SV-221221r508017_rule
SV-95233

Email system availability depends in part on best practice strategies for setting tuning configurations. This configuration controls the maximum number of simultaneous outbound connections from a domain and works in conjunction with the Maximum Outbound Connections Count setting as a delivery tuning mechanism. If the limit is too low, connections may be dropped. If the limit is too high, some domains may use a disproportionate resource share, denying access to other domains. Appropriate tuning reduces the risk of data delay or loss. By default, a limit of 20 simultaneous outbound connections from a domain should be sufficient. The value may be adjusted if justified by local site conditions.

Checks: C-22936r411789_chk

Review the Email Domain Security Plan (EDSP). Determine the value for Maximum Domain Connections. Open the Exchange Management Shell and enter the following command: Get-TransportService | Select Name, Identity, MaxPerDomainOutboundConnections If the value of "MaxPerDomainOutboundConnections" is not set to "20", this is a finding. or If the value of "MaxPerDomainOutboundConnections" is set to a value other than "20" and has signoff and risk acceptance in the EDSP, this is not a finding.

Fix: F-22925r411790_fix

Update the EDSP to reflect the value for Maximum Domain Connections. Open the Exchange Management Shell and enter the following command: Set-TransportService -Identity <'IdentityName'> -MaxPerDomainOutboundConnections 20 Note: The <IdentityName> value must be in single quotes. or The value as identified by the EDSP that has obtained a signoff with risk acceptance.

Exchange Send connector connections count must be limited.

SC-5 - Low - CCI-001095 - V-221222 - SV-221222r508017_rule

RMF Control

SC-5

Severity

CCI

CCI-001095

Version

EX16-ED-000230

Vuln IDs

V-221222
V-80525

Rule IDs

SV-221222r508017_rule
SV-95235

This setting controls the maximum number of simultaneous outbound connections allowed for a given SMTP Connector and can be used to throttle the SMTP service if resource constraints warrant it. If the limit is too low, connections may be dropped. If the limit is too high, some domains may use a disproportionate resource share, denying access to other domains. Appropriate tuning reduces the risk of data delay or loss.

Checks: C-22937r411792_chk

Review the Email Domain Security Plan (EDSP). Determine the value for SMTP Server Maximum Outbound Connections. Open the Exchange Management Shell and enter the following command: Get-TransportService | Select Name, Identity, MaxOutboundConnections If the value of "MaxOutboundConnections" is not set to "1000", this is a finding. or If the value of "MaxOutboundConnections" is set to a value other than "1000" and has signoff and risk acceptance in the EDSP, this is not a finding.

Fix: F-22926r411793_fix

Update the EDSP to reflect the value for SMTP Server Maximum Outbound Connections. Open the Exchange Management Shell and enter the following command: Set-TransportService -Identity <'IdentityName'> -MaxOutboundConnections 1000 Note: The <IdentityName> value must be in single quotes. or The value as identified by the EDSP that has obtained a signoff with risk acceptance.

Exchange message size restrictions must be controlled on Send connectors.

SC-5 - Low - CCI-001095 - V-221223 - SV-221223r508017_rule

RMF Control

SC-5

Severity

CCI

CCI-001095

Version

EX16-ED-000240

Vuln IDs

V-221223
V-80527

Rule IDs

SV-221223r508017_rule
SV-95237

Email system availability depends in part on best practice strategies for setting tuning configurations. For message size restrictions, multiple places exist to set or override inbound or outbound message size. Failure to control the configuration strategy can result in loss of data or system availability. This setting enables the administrator to control the maximum message size on a Send connector. Using connectors to control size limits may necessitate applying message size limitations in multiple places, with the potential of introducing conflicts and impediments in the mail flow. Changing this setting at the connector overrides the global one. Therefore, if operational needs require it, the connector value may be set lower than the global value with the rationale documented in the EDSP.

Checks: C-22938r411795_chk

Review the Email Domain Security Plan (EDSP). Determine the maximum message send size. Open the Exchange Management Shell and enter the following command: Get-SendConnector | Select Name, Identity, MaxMessageSize For each send connector, if the value of "MaxMessageSize" is not the same as the global value, this is a finding. or If "MaxMessageSize" is set to a numeric value different from the maximum message send size value documented in the EDSP, this is a finding.

Fix: F-22927r411796_fix

Update the EDSP to reflect the maximum message send size. Open the Exchange Management Shell and enter the following command: Set-SendConnector -Identity <'IdentityName'> -MaxMessageSize <MaxSendSize> Note: The <IdentityName> value must be in single quotes. or The value as identified by the EDSP that has obtained a signoff with risk acceptance. Repeat the procedure for each send connector.

Exchange Send connectors delivery retries must be controlled.

SC-5 - Low - CCI-001095 - V-221224 - SV-221224r508017_rule

RMF Control

SC-5

Severity

CCI

CCI-001095

Version

EX16-ED-000250

Vuln IDs

V-221224
V-80529

Rule IDs

SV-221224r508017_rule
SV-95239

This setting controls the rate at which delivery attempts from the home domain are retried and user notifications are issued and notes the expiration time when the message will be discarded. If delivery retry attempts are too frequent, servers will generate network congestion. If they are too far apart, messages may remain queued longer than necessary, potentially raising disk resource requirements. The default values of these fields should be adequate for most environments. Administrators may wish to modify the values, but changes should be documented in the System Security Plan. Note: Transport configuration settings apply to the organization/global level of the Exchange SMTP path. By checking and setting them at the Hub server, the setting will apply to both Hub and Edge roles.

Checks: C-22939r411798_chk

Review the Email Domain Security Plan (EDSP). Determine the value for Transient Failure Retry Count. Open the Exchange Management Shell and enter the following command: Get-TransportService | Select Name, Identity, TransientFailureRetryCount If the value of "TransientFailureRetryCount" is not set to "10" or less, this is a finding. or If the value of "TransientFailureRetryCount" is set to more than "10" or has signoff and risk acceptance in the EDSP, this is not a finding.

Fix: F-22928r411799_fix

Update the EDSP to reflect the value for Transient Failure Retry Count. Open the Exchange Management Shell and enter the following command: Set-TransportService -Identity <'IdentityName'> -TransientFailureRetryCount 10 Note: The <IdentityName> value must be in single quotes. or The value as identified by the EDSP that has obtained a signoff with risk acceptance.

Exchange Send connectors must be clearly named.

SC-5 - Low - CCI-001095 - V-221225 - SV-221225r508017_rule

RMF Control

SC-5

Severity

CCI

CCI-001095

Version

EX16-ED-000260

Vuln IDs

V-221225
V-80531

Rule IDs

SV-221225r508017_rule
SV-95241

For Send connectors, unclear naming as to direction and purpose increases risk that messages may not flow as intended, troubleshooting efforts may be impaired, or incorrect assumptions may be made about the completeness of the configuration. Collectively, connectors should account for all connections required for the overall email topology design. Simple Mail Transfer Protocol (SMTP) connectors, when listed, must name purpose and direction clearly, and their counterparts on servers to which they connect should be recognizable as their partners.

Checks: C-22940r411801_chk

Open the Exchange Management Shell and enter the following command: Get-SendConnector | Select Name, Identity Review the naming for connectors. For each send connector, if the connectors are not clearly named for purpose and direction, this is a finding.

Fix: F-22929r411802_fix

Open the Exchange Management Shell and enter the following command: Set-SendConnector -Name <'NewName'> -Identity <'IdentityName'> Note: Both the <NewName> and <IdentityName> values must be in single quotes. Repeat the procedure for each send connector.

Exchange Receive connector Maximum Hop Count must be 60.

SC-5 - Medium - CCI-001095 - V-221226 - SV-221226r508017_rule

RMF Control

SC-5

Severity

CCI

CCI-001095

Version

EX16-ED-000270

Vuln IDs

V-221226
V-80533

Rule IDs

SV-221226r508017_rule
SV-95243

Email system availability depends in part on best practice strategies for setting tuning configurations. This setting controls the maximum number of hops (email servers traversed) a message may take as it travels to its destination. Part of the original Internet protocol implementation, the hop count limit prevents a message from being passed in a routing loop indefinitely. Messages exceeding the maximum hop count are discarded undelivered. Recent studies indicate that virtually all messages can be delivered in fewer than 60 hops. If the hop count is set too low, messages may expire before they reach their destinations. If set too high, an undeliverable message may cycle between servers, raising the risk of network congestion.

Checks: C-22941r411804_chk

Review the Email Domain Security Plan (EDSP). Determine the value for Receive connectors. Open the Exchange Management Shell and enter the following command: Get-ReceiveConnector | Select Name, Identity, MaxHopCount For each receive connector, if the value of "MaxHopCount" is not set to "60", this is a finding. or If the value of "MaxHopCount" is set to a value other than "60" and has signoff and risk acceptance, this is not a finding.

Fix: F-22930r411805_fix

Update the EDSP to reflect the value for Receive connectors. Open the Exchange Management Shell and enter the following command: Set-ReceiveConnector -Identity <'IdentityName'> -MaxHopCount 60 Note: The <IdentityName> value must be in single quotes. or The value as identified by the EDSP that has obtained a signoff with risk acceptance. Repeat the procedure for each receive connector.

Exchange Receive connectors must be clearly named.

SC-5 - Low - CCI-001095 - V-221227 - SV-221227r508017_rule

RMF Control

SC-5

Severity

CCI

CCI-001095

Version

EX16-ED-000280

Vuln IDs

V-221227
V-80535

Rule IDs

SV-221227r508017_rule
SV-95245

For receive connectors, unclear naming as to direction and purpose increases risk that messages may not flow as intended, troubleshooting efforts may be impaired, or incorrect assumptions may be made about the completeness of the configuration. Collectively, connectors should account for all connections required for the overall email topology design. Simple Mail Transfer Protocol (SMTP) connectors, when listed, must name purpose and direction clearly, and their counterparts on servers to which they connect should be recognizable as their partners.

Checks: C-22942r495389_chk

Open the Exchange Management Shell and enter the following command: Get-ReceiveConnector | Select Name, Identity For each Receive connector, review the naming for connectors. If the connectors are not clearly named for purpose and direction, this is a finding.

Fix: F-22931r411808_fix

Open the Exchange Management Shell and enter the following command: Set-ReceiveConnector -Name <'NewName'> -Identity <'IdentityName'> Note: Both the <NewName> and <IdentityName> value must be in single quotes. Repeat the procedure for each receive connector.

Exchange Receive connectors must control the number of recipients chunked on a single message.

SC-5 - Low - CCI-001095 - V-221228 - SV-221228r508017_rule

RMF Control

SC-5

Severity

CCI

CCI-001095

Version

EX16-ED-000290

Vuln IDs

V-221228
V-80537

Rule IDs

SV-221228r508017_rule
SV-95247

Checks: C-22943r411810_chk

Open the Exchange Management Shell and enter the following command: Get-ReceiveConnector | Select Name, Identity, ChunkingEnabled For each receive connector, if the value of "ChunkingEnabled" is not set to "True", this is a finding.

Fix: F-22932r411811_fix

Open the Exchange Management Shell and enter the following command: Set-ReceiveConnector -Identity <'IdentityName'> -ChunkingEnabled $true Note: The <IdentityName> value must be in single quotes. Repeat the procedure for each receive connector.

Exchange Receive connectors must control the number of recipients per message.

SC-5 - Medium - CCI-001095 - V-221229 - SV-221229r561307_rule

RMF Control

SC-5

Severity

CCI

CCI-001095

Version

EX16-ED-000300

Vuln IDs

V-221229
V-80539

Rule IDs

SV-221229r561307_rule
SV-95249

Email system availability depends in part on best practice strategies for setting tuning configurations. This configuration controls the maximum number of recipients who will receive a copy of a message at one time. This tunable value is related to throughput capacity and can enable the ability to optimize message delivery. Note: There are two types of default Receive connecters: "Client Servername" accepts SMTP connections from all non-MAPI clients, such as POP and IMAP. As POP and IMAP are not authorized for use in DoD, these should not be present. Their default value for MaxRecipientsPerMessage is 200. IMAP Secure is not restricted and may be configured. "Default Servername" accepts connections from other mailbox servers and any Edge Transport servers. Their default value for MaxRecipientsPerMessage is 5000.

Checks: C-22944r411813_chk

Review the Email Domain Security Plan (EDSP). Determine the Maximum Recipients per Message value. Open the Exchange Management Shell and enter the following command: Get-ReceiveConnector | Select Name, Identity, MaxRecipientsPerMessage For each receive connector, if the value of "MaxRecipientsPerMessage" is not set to "5000", this is a finding. or If the value of "MaxRecipientsPerMessage" is set to a value other than "5000" and has signoff and risk acceptance in the EDSP, this is not a finding.

Fix: F-22933r411814_fix

Update the EDSP to reflect the Maximum Recipients per Message value. Open the Exchange Management Shell and enter the following command: Set-ReceiveConnector -Identity <'IdentityName'> -MaxRecipientsPerMessage 5000 Note: The <IdentityName> value must be in single quotes. or The value as identified by the EDSP that has obtained a signoff with risk acceptance. Repeat the procedure for each receive connector.

The Exchange Internet Receive connector connections count must be set to default.

SC-5 - Low - CCI-001095 - V-221230 - SV-221230r508017_rule

RMF Control

SC-5

Severity

CCI

CCI-001095

Version

EX16-ED-000310

Vuln IDs

V-221230
V-80541

Rule IDs

SV-221230r508017_rule
SV-95251

Email system availability depends in part on best practice strategies for setting tuning configurations. This configuration controls the maximum number of simultaneous inbound connections allowed to the SMTP server. By default, the number of simultaneous inbound connections is 5000. If a limit is set too low, the connections pool may be filled. If attackers perceive the limit is too low, they could deny service to the Simple Mail Transfer Protocol (SMTP) server by using a connection count that exceeds the limit set. By setting the default configuration to 5000, attackers would need many more connections to cause denial of service.

Checks: C-22945r411816_chk

Review the Email Domain Security Plan (EDSP). Determine the Maximum Inbound connections value. Open the Exchange Management Shell and enter the following command: Get-ReceiveConnector | Select Name, Identity, MaxInboundConnection Identify Internet-facing connectors. For each receive connector, if the value of "MaxInboundConnection" is not set to "5000", this is a finding. or If "MaxInboundConnection" is set to a value other than "5000" or is set to unlimited and has signoff and risk acceptance in the EDSP, this is not a finding.

Fix: F-22934r411817_fix

Update the EDSP to reflect the Maximum Inbound connections value. Open the Exchange Management Shell and enter the following command: Set-ReceiveConnector -Identity <'IdentityName'> -MaxInboundConnection 5000 Note: The <IdentityName> value must be in single quotes. or The value as identified by the EDSP that has obtained a signoff with risk acceptance. Repeat the procedure for each receive connector.

Exchange Message size restrictions must be controlled on Receive connectors.

SC-5 - Low - CCI-001095 - V-221231 - SV-221231r508017_rule

RMF Control

SC-5

Severity

CCI

CCI-001095

Version

EX16-ED-000320

Vuln IDs

V-221231
V-80543

Rule IDs

SV-221231r508017_rule
SV-95253

Email system availability depends in part on best practices strategies for setting tuning configurations. For message size restrictions, multiple places exist to set or override inbound or outbound message size. Failure to control the configuration strategy can result in loss of data or system availability. This setting enables the administrator to control the maximum message size on Receive connectors. Using connectors to control size limits may necessitate applying message size limitations in multiple places, with the potential of introducing conflicts and impediments in the mail flow. Changing this setting at the connector overrides the global one. Therefore, if operational needs require it, the connector value may be set lower than the global value with the rationale documented in the EDSP.

Checks: C-22946r411819_chk

Review the Email Domain Security Plan (EDSP). Determine the global maximum message receive size. Open the Exchange Management Shell and enter the following command: Identify Internet-facing connectors. Get-ReceiveConnector | Select Name, Identity, MaxMessageSize If the value of "MaxMessageSize" is not the same as the global value, this is a finding. or If "MaxMessageSize" is set to a numeric value different from the global value and has signoff and risk acceptance in the EDSP, this is not a finding.

Fix: F-22935r411820_fix

Update the EDSP to reflect the global maximum message receive size. Open the Exchange Management Shell and enter the following command: Set-ReceiveConnector -Identity <'IdentityName'> -MaxMessageSize <'MaxReceiveSize'> Note: The <IdentityName> and <MaxReceiveSize> values must be in single quotes. or The value as identified by the EDSP that has obtained a signoff with risk acceptance.

Exchange messages with a blank sender field must be rejected.

SI-8 - Medium - CCI-001308 - V-221232 - SV-221232r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000330

Vuln IDs

V-221232
V-80545

Rule IDs

SV-221232r508017_rule
SV-95255

By performing filtering at the perimeter, up to 90 percent of spam, malware, and other undesirable messages are eliminated from the message stream rather than admitting them into the mail server environment. Anonymous email (messages with blank sender fields) cannot be replied to. Messages formatted in this way may be attempting to hide their true origin to avoid responses or to spam any receiver with impunity while hiding their source of origination. Rather than spend resources and risk infection while evaluating them, it is recommended that these messages be filtered immediately upon receipt and not forwarded to end users.

Checks: C-22947r411822_chk

This requirement is N/A for SIPR enclaves. This requirement is N/A if the organization subscribes to EEMSG or other similar DoD enterprise protections for email services. Open the Exchange Management Shell and enter the following command: Get-SenderFilterConfig | Select Name, Action If the value of "Action" is not set to "Reject", this is a finding.

Fix: F-22936r411823_fix

Open the Exchange Management Shell and enter the following command: Set-SenderFilterConfig -Action Reject

Exchange messages with a blank sender field must be filtered.

SI-8 - Medium - CCI-001308 - V-221233 - SV-221233r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000340

Vuln IDs

V-221233
V-80547

Rule IDs

SV-221233r508017_rule
SV-95257

By performing filtering at the perimeter, up to 90 percent of spam, malware, and other undesirable messages are eliminated from the message stream rather than admitting them into the mail server environment. Anonymous email (messages with blank sender fields) cannot be replied to. Messages formatted in this way may be attempting to hide their true origin to avoid responses or to spam any receiver with impunity while hiding their source of origination. Rather than spend resources and risk infection while evaluating them, it is recommended that these messages be filtered immediately upon receipt and not forwarded to end users.

Checks: C-22948r411825_chk

This requirement is N/A for SIPR enclaves. This requirement is N/A if the organization subscribes to EEMSG or other similar DoD enterprise protections for email services. Open the Exchange Management Shell and enter the following command: Get-SenderFilterConfig | Select Name, BlankSenderBlockingEnabled If the value of "BlankSenderBlockingEnabled" is not set to "True", this is a finding.

Fix: F-22937r411826_fix

Open the Exchange Management Shell and enter the following command: Set-SenderFilterConfig -BlankSenderBlockingEnabled $true

Exchange filtered messages must be archived.

SI-8 - Medium - CCI-001308 - V-221234 - SV-221234r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000350

Vuln IDs

V-221234
V-80549

Rule IDs

SV-221234r508017_rule
SV-95259

By performing filtering at the perimeter, up to 90 percent of spam, malware, and other undesirable messages are eliminated from the message stream rather than admitting them into the mail server environment. This significantly reduces the attack vector for inbound email-borne spam and malware. As messages are filtered, it is prudent to temporarily host them in an archive for evaluation by administrators or users. The archive can be used to recover messages that might have been inappropriately filtered, preventing data loss, and to provide a base of analysis that can provide future filter refinements.

Checks: C-22949r411828_chk

Note: If third-party anti-spam product is being used, the anti-spam product must be configured to meet the requirement. Open the Exchange Management Shell and enter the following command: Get-ContentFilterConfig | Select Name, QuarantineMailbox If no SMTP address is assigned to "QuarantineMailbox", this is a finding.

Fix: F-22938r411829_fix

Open the Exchange Management Shell and enter the following command: Set-ContentFilterConfig -QuarantineMailbox <'QuarantineMailbox SmtpAddress'> Note: The <QuarantineMailbox SmtpAddress> value must be in single quotes.

The Exchange Sender filter must block unaccepted domains.

SI-8 - Medium - CCI-001308 - V-221235 - SV-221235r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000360

Vuln IDs

V-221235
V-80551

Rule IDs

SV-221235r508017_rule
SV-95261

Spam origination sites and other sources of suspected email-borne malware have the ability to corrupt, compromise, or otherwise limit availability of email servers. Limiting exposure to unfiltered inbound messages can reduce the risk of spam and malware impacts. The Global Deny list blocks messages originating from specific sources. Most blacklist filtering is done using a commercial Block List service, because eliminating threats from known spammers prevents the messages being evaluated inside the enclave where there is more risk they can do harm. Additional sources should also be blocked to supplement the contents of the commercial Block List service. For example, during a zero-day threat action, entries can be added and then removed when the threat is mitigated. An additional best practice is to enter the enterprise’s home domains in the Deny List, because inbound email with a "from" address of the home domain is very likely to be spoofed spam.

Checks: C-22950r411831_chk

Note: If third-party anti-spam product is being used, the anti-spam product must be configured to meet the requirement. Review the Email Domain Security Plan (EDSP). Determine the unaccepted domains that are to be blocked. Open the Exchange Management Shell and enter the following command: Get-SenderFilterConfig | Select Name, BlockedDomains, BlockedDomainsAndSubdomains If the value for "BlockedDomains" or "BlockedDomainsAndSubdomains" does not reflect the list of accepted domains, this is a finding.

Fix: F-22939r411832_fix

Update the EDSP to reflect the unaccepted domains that are to be blocked. Open the Exchange Management Shell and enter the following command: For BlockedDomains: Set-SenderFilterConfig -BlockedDomains <BlockedDomain> Repeat the procedure for each domain that is to be blocked. or For BlockedDomainsAndSubdomains: Set-SenderFilterConfig -BlockedDomainsAndSubdomains <BlockedDomainAndSubdomain> Repeat the procedure for each domain and all of its subdomains that are to be blocked.

Exchange nonexistent recipients must not be blocked.

SI-8 - Medium - CCI-001308 - V-221236 - SV-221236r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000370

Vuln IDs

V-221236
V-80553

Rule IDs

SV-221236r508017_rule
SV-95263

Spam originators, in an effort to refine mailing lists, sometimes use a technique where they first create fictitious names and then monitor rejected emails for non-existent recipients. Those not rejected are deemed to exist and are used in future spam mailings. To prevent this disclosure of existing email accounts to spammers, email to nonexistent recipients must not be blocked. Instead, it is recommended that all messages be received, then evaluated and disposed of without enabling the sender to determine existent vs. nonexistent recipients.

Checks: C-22951r411834_chk

Note: If third-party anti-spam product is being used, the anti-spam product must be configured to meet the requirement. Open the Exchange Management Shell and enter the following command: Get-RecipientFilterConfig | Select Name, RecipientValidationEnabled If the value of "RecipientValidationEnabled" is not set to "False", this is a finding.

Fix: F-22940r411835_fix

Open the Exchange Management Shell and enter the following command: Set-RecipientFilterConfig -RecipientValidationEnabled $false

The Exchange Sender Reputation filter must be enabled.

SI-8 - Medium - CCI-001308 - V-221237 - SV-221237r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000380

Vuln IDs

V-221237
V-80555

Rule IDs

SV-221237r508017_rule
SV-95265

By performing filtering at the perimeter, up to 90 percent of spam, malware, and other undesirable messages are eliminated from the message stream rather than admitting them into the mail server environment. Sender Reputation is antispam functionality that blocks messages according to many characteristics of the sender. Sender Reputation relies on persisted data about the sender to determine what action, if any, to take on an inbound message. This setting enables the Sender Reputation function.

Checks: C-22952r411837_chk

Note: If third-party anti-spam product is being used, the anti-spam product must be configured to meet the requirement. Open the Exchange Management Shell and enter the following command: Get-SenderReputationConfig | Select Name, Enabled If the value of "Enabled" is not set to "True", this is a finding.

Fix: F-22941r411838_fix

Open the Exchange Management Shell and enter the following command: Set-SenderReputationConfig -Enabled $true

The Exchange Sender Reputation filter must identify the spam block level.

SI-8 - Medium - CCI-001308 - V-221238 - SV-221238r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000390

Vuln IDs

V-221238
V-80557

Rule IDs

SV-221238r508017_rule
SV-95267

By performing filtering at the perimeter, up to 90 percent of spam, malware, and other undesirable messages are eliminated from the message stream rather than admitting them into the mail server environment. Sender Reputation is antispam functionality that blocks messages according to many characteristics of the sender. Sender Reputation relies on persisted data about the sender to determine what action, if any, to take on an inbound message. This setting enables the threshold at which an email will be considered spam.

Checks: C-22953r411840_chk

Note: If third-party anti-spam product is being used, the anti-spam product must be configured to meet the requirement. Review the Email Domain Security Plan (EDSP). Determine the SrlBlockThreshold value. Open the Exchange Management Shell and enter the following command: Get-SenderReputationConfig | Select Name, SrlBlockThreshold If the value of SrlBlockThreshold is not set to "6", this is a finding. or If the value of "SrlBlockThreshold" is set to a value other than "6" and has signoff and risk acceptance in the EDSP, this is not a finding.

Fix: F-22942r411841_fix

Update the EDSP to reflect the SrlBlockThreshold size. Open the Exchange Management Shell and enter the following command: Set-SenderReputationConfig -SrlBlockThreshold 6 or The value as identified by the EDSP that has obtained a signoff with risk acceptance.

Exchange Attachment filtering must remove undesirable attachments by file type.

SI-8 - Medium - CCI-001308 - V-221239 - SV-221239r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000400

Vuln IDs

V-221239
V-80559

Rule IDs

SV-221239r508017_rule
SV-95269

By performing filtering at the perimeter, up to 90 percent of spam, malware, and other undesirable messages are eliminated from the message stream rather than admitting them into the mail server environment. Attachments are being used more frequently for different forms of attacks. By filtering undesirable attachments, a large percent of malicious code can be prevented from entering the system. Attachments must be controlled at the entry point into the email environment to prevent successful attachment-based attacks. The following is a basic list of known attachments that should be filtered from Internet mail attachments: *.ade *.crt *.jse *.msi *.scr *.wsh *.dir *.adp *.csh *.ksh *.msp *.sct *.htm *.dcr *.app *.exe *.lnk *.mst *.shb *.html *.plg *.asx *.fxp *.mda *.ops *.shs *.htc *.spl *.bas *.hlp *.mdb *.pcd *.url *.mht *.swf *.bat *.hta *.mde *.pif *.vb *.mhtml *.zip *.chm *.inf *.mdt *.prf *.vbe *.shtm *.cmd *.ins *.mdw *.prg *.vbs *.shtml *.com *.isp *.mdz *.reg *.wsc *.stm *.cpl *.js *.msc *.scf *.wsf *.xml

Checks: C-22954r411843_chk

Note: If third-party anti-spam product is being used, the anti-spam product must be configured to meet the requirement. Review the Email Domain Security Plan (EDSP). Determine the list of undesirable attachment types that should be stripped. Open the Exchange Management Shell and enter the following command: Get-AttachmentFilterEntry For each attachment type, if the values returned are different from the EDSP documented attachment types, this is a finding.

Fix: F-22943r411844_fix

Update the EDSP to reflect the list of undesirable attachment types that should be stripped. Open the Exchange Management Shell and enter the following command: Add-AttachmentFilterEntry -Name <'*.FileExtension'> -Type FileName Repeat the procedure for each undesirable attachment type.

The Exchange Spam Evaluation filter must be enabled.

SI-8 - Medium - CCI-001308 - V-221240 - SV-221240r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000410

Vuln IDs

V-221240
V-80561

Rule IDs

SV-221240r508017_rule
SV-95271

By performing filtering at the perimeter, up to 90 percent of spam, malware, and other undesirable messages may be eliminated from the transport message stream, preventing their entry into the Exchange environment. This significantly reduces the attack vector for inbound email-borne spam and malware. Spam Evaluation filters scan inbound email messages for evidence of spam and other attacks that primarily use "social engineering" techniques. Upon evaluation completion, a rating is assigned to each message estimating the likelihood of its being spam. Upon arrival at the destination mailbox, the junk mail filter threshold (also configurable) determines whether the message will be withheld from delivery, delivered to the junk mail folder, or delivered to the user’s inbox.

Checks: C-22955r411846_chk

Note: If third-party anti-spam product is being used, the anti-spam product must be configured to meet the requirement. Open the Exchange Management Shell and enter the following command: Get-ContentFilterConfig | Select Name, Identity, Enabled If the value of "Enabled" is not set to "True", this is a finding.

Fix: F-22944r411847_fix

Open the Exchange Management Shell and enter the following command: Set-ContentFilterConfig -Enabled $true

The Exchange Block List service provider must be identified.

SI-8 - Medium - CCI-001308 - V-221241 - SV-221241r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000420

Vuln IDs

V-221241
V-80563

Rule IDs

SV-221241r508017_rule
SV-95273

Block List filtering is a sanitization process performed on email messages prior to their arrival at the destination mailbox. By performing this process at the email perimeter, threats can be eliminated outside the enclave, where there is less risk for them to do harm. Block List services (sometimes called Reputation Data services) are fee-based data providers that collect the IP addresses of known spammers and other malware purveyors. Block List service subscribers benefit from more effective spam elimination. (Spam is estimated to compose up to 90 percent of inbound mail volume.) Failure to specify a Block List provider risks that manual email administration effort would be needed to maintain and update larger Block Lists than a single email site administrator could conveniently or accurately maintain. The Block List service vendor provides a value for this field, usually the Domain Name System (DNS) suffix for its domain.

Checks: C-22956r411849_chk

If not using a service provider, this requirement is not applicable. Review the Email Domain Security Plan (EDSP). Determine the name and information for the Block List provider. Open the Exchange Management Shell and enter the following command: Get-IPBlockListProvider | Select Name, Identity, LookupDomain If the values for "Name", GUID, and "LookupDomain" are not configured, this is a finding.

Fix: F-22945r411850_fix

Update the EDSP to reflect the name and information for the Block List provider. Open the Exchange Management Shell and enter the following command: Set-IPBlockListProvider -Name <Provider Name> [Additional optional parameters as required by the service provider]

Exchange messages with a malformed From address must be rejected.

SI-8 - Medium - CCI-001308 - V-221242 - SV-221242r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000430

Vuln IDs

V-221242
V-80565

Rule IDs

SV-221242r508017_rule
SV-95275

Sender Identification (SID) is an email antispam sanitization process. Sender ID uses DNS MX record lookups to verify the Simple Mail Transfer Protocol (SMTP) sending server is authorized to send email for the originating domain. Failure to implement Sender ID risks that spam could be admitted into the email domain that originates from rogue servers. Most spam content originates from domains where the IP address has been spoofed prior to sending, thereby avoiding detection. For example, messages with malformed or incorrect "purported responsible sender" data in the message header could be (best case) created by using RFI noncompliant software but is more likely to be spam.

Checks: C-22957r411852_chk

Note: If third-party anti-spam product is being used, the anti-spam product must be configured to meet the requirement. Open the Exchange Management Shell and enter the following command: Get-SenderIdConfig | Select Name, Identity, SpoofedDomainAction If the value of "SpoofedDomainAction" is not set to "Reject", this is a finding.

Fix: F-22946r411853_fix

Open the Exchange Management Shell and enter the following command: Set-SenderIdConfig -SpoofedDomainAction Reject

The Exchange Recipient filter must be enabled.

SI-8 - Medium - CCI-001308 - V-221243 - SV-221243r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000470

Vuln IDs

V-221243
V-80567

Rule IDs

SV-221243r508017_rule
SV-95277

Checks: C-22958r411855_chk

Open the Exchange Management Shell and enter the following command: Get-RecipientFilterConfig | Select Name, Enabled If the value of "Enabled" is not set to "True", this is a finding.

Fix: F-22947r411856_fix

Open the Exchange Management Shell and enter the following command: Set-RecipientFilterConfig -Enabled $true

The Exchange tarpitting interval must be set.

SI-8 - Medium - CCI-001308 - V-221244 - SV-221244r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000480

Vuln IDs

V-221244
V-80569

Rule IDs

SV-221244r508017_rule
SV-95279

Tarpitting is the practice of artificially delaying server responses for specific Simple Mail Transfer Protocol (SMTP) communication patterns that indicate high volumes of spam or other unwelcome messages. The intent of tarpitting is to slow down the communication process for spam batches to reduce the cost effectiveness of sending spam and thwart directory harvest attacks. A directory harvest attack is an attempt to collect valid email addresses from a particular organization so the email addresses can be added to a spam database. A program can be written to collect email addresses that return a "Recipient OK" SMTP response and discard all email addresses that return a "User unknown" SMTP response. Tarpitting makes directory harvest attacks too costly to automate efficiently.

Checks: C-22959r411858_chk

Open the Exchange Management Shell and enter the following command: Get-ReceiveConnector | Select Name, Identity, TarpitInterval For each Receive connector, if the value of "TarpitInterval" is not set to "00:00:05" or greater, this is a finding.

Fix: F-22948r411859_fix

Open the Exchange Management Shell and enter the following command: Set-ReceiveConnector -Identity <'IdentityName'> -TarpitInterval '00:00:05' Note: The <IdentityName> value and the Interval must be in single quotes. Repeat the procedures for each Receive connector.

Exchange internal Receive connectors must not allow anonymous connections.

SI-8 - Medium - CCI-001308 - V-221245 - SV-221245r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000490

Vuln IDs

V-221245
V-80571

Rule IDs

SV-221245r508017_rule
SV-95281

This control is used to limit the servers that may use this server as a relay. If a Simple Mail Transport Protocol (SMTP) sender does not have a direct connection to the Internet (for example, an application that produces reports to be emailed), it will need to use an SMTP Receive connector that does have a path to the Internet (for example, a local email server) as a relay. SMTP relay functions must be protected so third parties are not able to hijack a relay service for their own purposes. Most commonly, relay hijacking is done by spammers to disguise the source of their messages and may also be used to cover the source of more destructive attacks. Relays can be restricted in one of three ways: by blocking relays (restrict to a blank list of servers); by restricting use to lists of valid servers; or by restricting use to servers that can authenticate. Because authenticated connections are the most secure for SMTP Receive connectors, it is recommended that relays allow only servers that can authenticate.

Checks: C-22960r411861_chk

Open the Exchange Management Shell and enter the following command: Get-ReceiveConnector | Select Name, Identity, PermissionGroups For each Receive connector, if the value of "PermissionGroups" is "AnonymousUsers" for any non-Internet connector, this is a finding.

Fix: F-22949r411862_fix

Open the Exchange Management Shell and enter the following command: Set-ReceiveConnector -Identity <'IdentityName'> -PermissionGroups 'valid user group(s)' Note: The <IdentityName> value and user group(s) must be in single quotes. Example for user groups only: 'ExchangeServers, ExchangeUsers' Repeat the procedures for each Receive connector. This is an Example only: Set-ReceiveConnector -Identity <'IdentityName'> -PermissionGroups 'ExchangeUsers'

Exchange Simple Mail Transfer Protocol (SMTP) IP Allow List entries must be empty.

SI-8 - Medium - CCI-001308 - V-221246 - SV-221246r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000500

Vuln IDs

V-221246
V-80573

Rule IDs

SV-221246r508017_rule
SV-95283

Email system availability depends in part on best practice strategies for setting tuning configurations. Careful tuning reduces the risk that system or network congestion will contribute to availability impacts. Filters that govern inbound email evaluation can significantly reduce spam, phishing, and spoofed emails. Filters for messages from blank senders, known spammers, or zero-day attack modifications must be enabled to be effective. Having items identified in the Allow List causes other spam evaluation steps to be bypassed and therefore should be used only with an abundance of caution. If spammers were to learn of entries in the Allow List, it could enable them to plan a denial of service attack (or other attack) by spoofing that source.

Checks: C-22961r411864_chk

Review the Email Domain Security Plan (EDSP). Identify the SMTP allow list settings. Open the Exchange Management Shell and enter the following command: Get-IPAllowListEntry | fl If the result returns any values, this is a finding. or If the result returns any values but has signoff and risk acceptance in the EDSP, this is not a finding.

Fix: F-22950r411865_fix

Update the EDSP to reflect the SMTP allow list settings. Open the Exchange Management Shell and enter the following command: Note: Remove any value(s) that are not identified by the EDSP or have not obtained a signoff with risk acceptance. Remove-IPAllowListEntry -Identity <IP Allow List entry ID>

The Exchange Simple Mail Transfer Protocol (SMTP) IP Allow List Connection filter must be enabled.

SI-8 - Medium - CCI-001308 - V-221247 - SV-221247r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000510

Vuln IDs

V-221247
V-80575

Rule IDs

SV-221247r508017_rule
SV-95285

Checks: C-22962r411867_chk

Open the Exchange Management Shell and enter the following command: Get-IPAllowListConfig | Select Name, Enabled If the value for "Enabled" is not set to "True", this is a finding.

Fix: F-22951r411868_fix

Open the Exchange Management Shell and enter the following command: Set-IPAllowListConfig -Enabled $true

The Exchange Simple Mail Transfer Protocol (SMTP) Sender filter must be enabled.

SI-8 - Medium - CCI-001308 - V-221248 - SV-221248r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000520

Vuln IDs

V-221248
V-80577

Rule IDs

SV-221248r508017_rule
SV-95287

Email system availability depends in part on best practices strategies for setting tuning configurations. Careful tuning reduces the risk that system or network congestion will contribute to availability impacts. Filters that govern inbound email evaluation can significantly reduce spam, phishing, and spoofed emails. Filters for messages from blank senders, known spammers, or zero-day attack modifications must be enabled to be effective. Failure to enable the filter will result in no action taken. This setting should always be enabled.

Checks: C-22963r411870_chk

This requirement is N/A for SIPR enclaves. This requirement is N/A if the organization subscribes to EEMSG or other similar DoD enterprise protections for email services. Open the Exchange Management Shell and enter the following command: Get-SenderFilterConfig | Select Name, Enabled If the value of "Enabled" is not set to "True", this is a finding.

Fix: F-22952r411871_fix

Open the Exchange Management Shell and enter the following command: Set-SenderFilterConfig -Enabled $true

Exchange must have antispam filtering installed.

SI-8 - Medium - CCI-001308 - V-221249 - SV-221249r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000530

Vuln IDs

V-221249
V-80579

Rule IDs

SV-221249r508017_rule
SV-95289

Originators of spam messages are constantly changing their techniques in order to defeat spam countermeasures; therefore, spam software must be constantly updated to address the changing threat. Spam protection mechanisms include, for example, signature definitions, rule sets, and algorithms. Exchange 2016 provides both antispam and antimalware protection out of the box. The Exchange 2016 antispam and antimalware product capabilities are limited but still provide some protection.

Checks: C-22964r411873_chk

Fix: F-22953r411874_fix

Install the AntiSpam module. Open the Exchange Management Shell and enter the following command: & $env:ExchangeInstallPath\Scripts\Install-AntiSpamAgents.ps1

Exchange must have antispam filtering enabled.

SI-8 - Medium - CCI-001308 - V-221250 - SV-221250r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000540

Vuln IDs

V-221250
V-80581

Rule IDs

SV-221250r508017_rule
SV-95291

Checks: C-22965r411876_chk

Review the Email Domain Security Plan (EDSP) for an installed antispam product. Note: If using another DoD-approved antispam product for email or a DoD-approved Email Gateway spamming device, such as Enterprise Email Security Gateway (EEMSG), this is not applicable. Open the Exchange Management Shell and enter the following command: Get-ContentFilterConfig | Format-Table Name, Enabled; Get-SenderFilterConfig | Format-Table Name, Enabled; Get-SenderIDConfig | Format-Table Name, Enabled; Get-SenderReputationConfig | Format-Table Name, Enabled If any of the following values returned are not set to "True", this is a finding: Set-ContentFilterConfig Set-SenderFilterConfig Set-SenderIDConfig Set-SenderReputationConfig

Fix: F-22954r411877_fix

Open the Exchange Management Shell and enter the following command for any values that were not set to True: Set-ContentFilterConfig -Enabled $true Set-SenderFilterConfig -Enabled $true Set-SenderIDConfig -Enabled $true Set-SenderReputationConfig -Enabled $true

Exchange must have antispam filtering configured.

SI-8 - Medium - CCI-001308 - V-221251 - SV-221251r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000550

Vuln IDs

V-221251
V-80583

Rule IDs

SV-221251r508017_rule
SV-95293

Originators of spam messages are constantly changing their techniques in order to defeat spam countermeasures; therefore, spam software must be constantly updated to address the changing threat. A manual update procedure is labor intensive and does not scale well in an enterprise environment. This risk may be mitigated by using an automatic update capability. Spam protection mechanisms include, for example, signature definitions, rule sets, and algorithms. Exchange 2016 provides both antispam and antimalware protection out of the box. The Exchange 2016 antispam and antimalware product capabilities are limited but still provide some protection.

Checks: C-22966r411879_chk

Site should utilize an approved DoD scanner as Exchange Malware software has a limited scanning capability. If an approved DoD scanner is not being used, this is a finding.

Fix: F-22955r411880_fix

Following vendor best practice guidance, install and configure a DoD approved scanner.

Exchange Sender Identification Framework must be enabled.

SI-8 - Medium - CCI-001308 - V-221252 - SV-221252r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000560

Vuln IDs

V-221252
V-80585

Rule IDs

SV-221252r508017_rule
SV-95295

Email is only as secure as the recipient. When the recipient is an email server accepting inbound messages, authenticating the sender enables the receiver to better assess message quality and to validate the sending domain as authentic. One or more authentication techniques used in combination can be effective in reducing spam, phishing, and forger attacks. The Sender ID Framework (SIDF) receiver accesses specially formatted DNS records (SPF format) that contain the IP address of authorized sending servers for the sending domain that can be compared to data in the email message header. Receivers are able to validate the authenticity of the sending domain, helping to avoid receiving inbound messages from phishing or other spam domains.

Checks: C-22967r411882_chk

Note: If third-party anti-spam product is being used, the anti-spam product must be configured to meet the requirement. Open the Exchange Management Shell and enter the following command: Get-SenderIdConfig | Select Name, Identity, Enabled If the value of "Enabled" is not set to "True", this is a finding.

Fix: F-22956r411883_fix

Open the Exchange Management Shell and enter the following command: Set-SenderIdConfig -Enable $true

Exchange must strip hyperlink email sources from non-.mil domains.

SI-8 - High - CCI-001308 - V-221253 - SV-221253r508017_rule

RMF Control

SI-8

Severity

CCI

CCI-001308

Version

EX16-ED-000570

Vuln IDs

V-221253
V-80587

Rule IDs

SV-221253r508017_rule
SV-95297

Active hyperlinks within an email are susceptible to attacks of malicious software or malware. The hyperlink could lead to a malware infection or redirect the website to another fraudulent website without the user's consent or knowledge. Exchange does not have a built-in message filtering capability. DoD Enterprise Email (DEE) has created a custom resolution to filter messages from non-.mil users that have hyperlinks in the message body. The hyperlink within the messages will be modified, preventing end users from automatically clicking links.

Checks: C-22968r411885_chk

Note: If using another DoD-approved antispam product for email or a DoD-approved Email Gateway spamming device, such as Enterprise Email Security Gateway (EEMSG), this is not applicable. Note: If system is on SIPRNet, this is not applicable. Review the Email Domain Security Plan (EDSP). Determine the name of the Transport Agent. Open the Windows PowerShell console and enter the following command: Get-TransportAgent -Name 'customAgent' | FL If the value does not return "customAgent", this is a finding. Note: "customAgent" is the name of the custom agent developed to strip hyperlink email sources from non .mil domains and must be in single quot

Fix: F-22957r411886_fix

Update the EDSP to reflect the name of the Transport Agent. Contact the DISA Enterprise Email Service Desk at disa.tinker.eis.mbx.dod-enterprise-services-service-desk@mail.mil and request the Agent and installation procedures. or Contact DEE Engineering PMO and request the Agent and installation procedures.

The Exchange application directory must be protected from unauthorized access.

CM-11 - Medium - CCI-001812 - V-221254 - SV-221254r508017_rule

RMF Control

CM-11

Severity

CCI

CCI-001812

Version

EX16-ED-000580

Vuln IDs

V-221254
V-80589

Rule IDs

SV-221254r508017_rule
SV-95299

Default product installations may provide more generous access permissions than are necessary to run the application. By examining and tailoring access permissions to more closely provide the least amount of privilege possible, attack vectors that align with user permissions are less likely to access more highly secured areas.

Checks: C-22969r411888_chk

Review the Email Domain Security Plan (EDSP). Determine the authorized groups and users that have access to the Exchange application directories. Determine if the access permissions on the directory match the access permissions listed in the EDSP. If any group or user has different access permissions than listed in the EDSP, this is a finding. Note: The default installation directory is \Program Files\Microsoft\Exchange Server\V15.

Fix: F-22958r411889_fix

Update the EDSP to reflect the authorized groups and users that have access to the Exchange application directories. Navigate to the Exchange application directory and remove or modify the group or user access permissions. Note: The default installation directory is \Program Files\Microsoft\Exchange Server\V15.

The Exchange software baseline copy must exist.

CM-5 - Medium - CCI-001813 - V-221255 - SV-221255r508017_rule

RMF Control

CM-5

Severity

CCI

CCI-001813

Version

EX16-ED-000590

Vuln IDs

V-221255
V-80591

Rule IDs

SV-221255r508017_rule
SV-95301

Exchange software, as with other application software installed on a host system, must be included in a system baseline record and periodically reviewed; otherwise, unauthorized changes to the software may not be discovered. This effort is a vital step to securing the host and the applications, as it is the only method that may provide the ability to detect and recover from otherwise undetected changes, such as those that result from worm or bot intrusions. The Exchange software and configuration baseline is created and maintained for comparison during scanning efforts. Operational procedures must include baseline updates as part of configuration management tasks that change the software and configuration.

Checks: C-22970r411891_chk

Review the Email Domain Security Plan (EDSP). Determine the baseline documentation. Review the application software baseline procedures and implementation artifacts. Note the list of files and directories included in the baseline procedure for completeness. If an email software copy exists to serve as a baseline and is available for comparison during scanning efforts, this is not a finding.

Fix: F-22959r411892_fix

Implement an email software baseline process and update the EDSP.

Exchange services must be documented and unnecessary services must be removed or disabled.

CM-7 - Medium - CCI-001762 - V-221256 - SV-221256r508017_rule

RMF Control

CM-7

Severity

CCI

CCI-001762

Version

EX16-ED-000610

Vuln IDs

V-221256
V-80593

Rule IDs

SV-221256r508017_rule
SV-95303

Unneeded but running services offer attackers an enhanced attack profile, and attackers are constantly watching to discover open ports with running services. By analyzing and disabling unneeded services, the associated open ports become unresponsive to outside queries, and servers become more secure as a result. Exchange Server has role-based server deployment to enable protocol path control and logical separation of network traffic types. For example, a server implemented in the Client Access role (i.e., Outlook Web App [OWA]) is configured and tuned as a web server using web protocols. A client access server exposes only web protocols (HTTP/HTTPS), enabling system administrators to optimize the protocol path and disable all services unnecessary for Exchange web services. Similarly, servers created to host mailboxes are dedicated to that task and must operate only the services needed for mailbox hosting. (Exchange servers must also operate some web services, but only to the degree that Exchange requires the IIS engine in order to function). Because POP3 and IMAP4 clients are not included in the standard desktop offering, they must be disabled.

Checks: C-22971r411894_chk

Review the Email Domain Security Plan (EDSP). Note: Required services will vary between organizations and will vary depending on the role of the individual system. Organizations will develop their own list of services, which will be documented and justified with the ISSO. The site’s list will be provided for any security review. Services that are common to multiple systems can be addressed in one document. Exceptions for individual systems should be identified separately by system. Open a Windows PowerShell and enter the following command: Get-Service | Where-Object {$_.status -eq 'running'} Note: The command returns a list of installed services and the status of that service. If the services required are not documented in the EDSP or undocumented or unnecessary services are running, this is a finding.

Fix: F-22960r411895_fix

Update the EDSP with the services required for the system to function. Navigate to Administrator Tools >> Services and disable or remove any services that are not required.

Exchange software must be installed on a separate partition from the OS.

SC-39 - Medium - CCI-002530 - V-221257 - SV-221257r508017_rule

RMF Control

SC-39

Severity

CCI

CCI-002530

Version

EX16-ED-000620

Vuln IDs

V-221257
V-80595

Rule IDs

SV-221257r508017_rule
SV-95305

In the same way that added security layers can provide a cumulative positive effect on security posture, multiple applications can provide a cumulative negative effect. A vulnerability and subsequent exploit to one application can lead to an exploit of other applications sharing the same security context. For example, an exploit to a web server process that leads to unauthorized administrative access to the host system can most likely lead to a compromise of all applications hosted by the same system. Email services should be installed on a partition that does not host other applications. Email services should never be installed on a Domain Controller/Directory Services server.

Checks: C-22972r411897_chk

Review the Email Domain Security Plan (EDSP). Determine the directory where Exchange is installed. Open Windows Explorer. Navigate to the location where Exchange is installed. If Exchange resides on a directory or partition other than that of the OS and does not have other applications installed (without associated approval from the ISSO), this is not a finding.

Fix: F-22961r411898_fix

Update the EDSP to reflect the directory where Exchange is installed. Install Exchange on a dedicated application directory or partition separate than that of the OS.

The Exchange SMTP automated banner response must not reveal server details.

SC-5 - Medium - CCI-002385 - V-221258 - SV-221258r508017_rule

RMF Control

SC-5

Severity

CCI

CCI-002385

Version

EX16-ED-000630

Vuln IDs

V-221258
V-80597

Rule IDs

SV-221258r508017_rule
SV-95307

Automated connection responses occur as a result of FTP or Telnet connections when connecting to those services. They report a successful connection by greeting the connecting client and stating the name, release level, and (often) additional information about the responding product. While useful to the connecting client, connection responses can also be used by a third party to determine operating system or product release levels on the target server. The result can include disclosure of configuration information to third parties, paving the way for possible future attacks. For example, when querying the SMTP service on port 25, the default response looks similar to this one: 220 exchange.mydomain.org Microsoft ESMTP MAIL Service, Version: 6.0.3790.211 ready at Wed, 2 Feb 2005 23:40:00 -0500 Changing the response to hide local configuration details reduces the attack profile of the target.

Checks: C-22973r411900_chk

Open the Exchange Management Shell and enter the following command: Get-ReceiveConnector | Select Name, Identity, Banner If the value of "Banner" is not set to "220 SMTP Server Ready", this is a finding.

Fix: F-22962r411901_fix

Open the Exchange Management Shell and enter the following command: Set-ReceiveConnector -Identity <'IdentityName'> -Banner '220 SMTP Server Ready' Note: The <IdentityName> and 220 SMTP Server Ready values must be in single quotes.

Exchange must provide redundancy.

SC-8 - High - CCI-002418 - V-221259 - SV-221259r508017_rule

RMF Control

SC-8

Severity

CCI

CCI-002418

Version

EX16-ED-000660

Vuln IDs

V-221259
V-80599

Rule IDs

SV-221259r508017_rule
SV-95309

Denial of Service (DoS) is a condition when a resource is not available for legitimate users. When this occurs, the organization either cannot accomplish its mission or must operate at degraded capacity. This requirement addresses the configuration of applications to mitigate the impact of DoS attacks that have occurred or are ongoing on application availability. For each application, known and potential DoS attacks must be identified and solutions for each type implemented. A variety of technologies exist to limit or, in some cases, eliminate the effects of DoS attacks (e.g., limiting processes or restricting the number of sessions the application opens at one time). Employing increased capacity and bandwidth, combined with service redundancy, may reduce the susceptibility to some DoS attacks.

Checks: C-22974r411903_chk

Review the Email Domain Security Plan (EDSP). Determine if the Exchange servers are using redundancy by entering the following command: Get-TransportService | select FL If the value returned is not at least two Edge servers, this is a finding.

Fix: F-22963r411904_fix

Update the EDSP to reflect the Exchange servers used for redundancy. Configure two or more Edge servers for load balancing.

Exchange internal Send connectors must use an authentication level.

SC-5 - Medium - CCI-002385 - V-221260 - SV-221260r508017_rule

RMF Control

SC-5

Severity

CCI

CCI-002385

Version

EX16-ED-000670

Vuln IDs

V-221260
V-80601

Rule IDs

SV-221260r508017_rule
SV-95311

The Simple Mail Transfer Protocol (SMTP) connector is used by Exchange to send and receive messages from server to server. Several controls work together to provide security between internal servers. This setting controls the encryption method used for communications between servers. With this feature enabled, only servers capable of supporting Transport Layer Security (TLS) will be able to send and receive mail within the domain. The use of secure communication prevents eavesdroppers from reading or modifying communications between mail clients and servers. While sensitive message bodies should be encrypted by the sender at the client, requiring a secure connection from server to server adds protection by encrypting the sender and recipient information that cannot be encrypted by the sender. Individually, channel security and encryption can be compromised by attackers. Used together, email becomes a more difficult target, and security is heightened. Failure to enable this feature gives eavesdroppers an opportunity to read or modify messages between servers.

Checks: C-22975r411906_chk

Open the Exchange Management Shell and enter the following command: Get-SendConnector | Select Name, Identity, TlsAuthLevel If the value of "TlsAuthLevel" is not set to "DomainValidation", this is a finding.

Fix: F-22964r411907_fix

Open the Exchange Management Shell and enter the following command: Set-SendConnector -Identity <'IdentityName'> -TlsAuthLevel DomainValidation

Exchange internal Receive connectors must require encryption.

SC-8 - High - CCI-002418 - V-221261 - SV-221261r508017_rule

RMF Control

SC-8

Severity

CCI

CCI-002418

Version

EX16-ED-000680

Vuln IDs

V-221261
V-80753

Rule IDs

SV-221261r508017_rule
SV-95463

The Simple Mail Transfer Protocol (SMTP) Receive connector is used by Exchange to send and receive messages from server to server using SMTP protocol. This setting controls the encryption strength used for client connections to the SMTP Receive connector. With this feature enabled, only clients capable of supporting secure communications will be able to send mail using this SMTP server. Where secure channels are required, encryption can also be selected. The use of secure communication prevents eavesdroppers from reading or modifying communications between mail clients and servers. While sensitive message bodies should be encrypted by the sender at the client, requiring a secure connection from the client to the server adds protection by encrypting the sender and recipient information that cannot be encrypted by the sender. Individually, channel security and encryption have been compromised by attackers. Used together, email becomes a more difficult target, and security is heightened. Failure to enable this feature gives eavesdroppers an opportunity to read or modify messages between the client and server.

Checks: C-22976r411909_chk

Open the Exchange Management Shell and enter the following command: Get-ReceiveConnector | Select Name, Identity, AuthMechanism For each Receive connector, if the value of "AuthMechanism" is not set to "Tls", this is a finding.

Fix: F-22965r411910_fix

Open the Exchange Management Shell and enter the following command: Set-ReceiveConnector -Identity <'IdentityName'> -AuthMechanism 'Tls' Note: The <IdentityName> value must be in single quotes. Repeat the process for each Receive connector.

Exchange internal Send connectors must require encryption.

SC-8 - High - CCI-002418 - V-221262 - SV-221262r508017_rule

RMF Control

SC-8

Severity

CCI

CCI-002418

Version

EX16-ED-000690

Vuln IDs

V-221262
V-80603

Rule IDs

SV-221262r508017_rule
SV-95313

The Simple Mail Transfer Protocol (SMTP) connector is used by Exchange to send and receive messages from server to server. Several controls work together to provide security between internal servers. This setting controls the encryption method used for communications between servers. With this feature enabled, only servers capable of supporting Transport Layer Security (TLS) will be able to send and receive mail within the domain. The use of secure communication prevents eavesdroppers from reading or modifying communications between mail clients and servers. While sensitive message bodies should be encrypted by the sender at the client, requiring a secure connection from server to server adds protection by encrypting the sender and recipient information that cannot be encrypted by the sender. Individually, channel security and encryption can be compromised by attackers. Used together, email becomes a more difficult target, and security is heightened. Failure to enable this feature gives eavesdroppers an opportunity to read or modify messages between servers.

Checks: C-22977r457887_chk

Open the Exchange Management Shell and enter the following command: Get-SendConnector | Select Name, Identity, TlsDomain If the value of "TlsDomain" is not set to the value of the internal <'SMTP Domain'>, this is a finding. Get-SendConnector | Select Name, Identity, DomainSecureEnabled If the value of 'DomainSecureEnabled' is not set to 'True', this is a finding.

Fix: F-22966r457888_fix

Open the Exchange Management Shell and enter the following command: Set-SendConnector -Identity <'IdentityName'> -TlsDomain <'SMTP Domain'> Set-SendConnector -Identity <'ReceiveConnector'> -DomainSecureEnabled 'True' Note: The SMTP Domain is the internal SMTP domain within the organization.

Exchange must have the most current, approved service pack installed.

SI-2 - Medium - CCI-002605 - V-221263 - SV-221263r508017_rule

RMF Control

SI-2

Severity

CCI

CCI-002605

Version

EX16-ED-000700

Vuln IDs

V-221263
V-80605

Rule IDs

SV-221263r508017_rule
SV-95315

The organization (including any contractor to the organization) must promptly install security-relevant software updates (e.g., patches, service packs, hot fixes). Flaws discovered during security assessments, continuous monitoring, incident response activities, or information system error handling must also be addressed.

Checks: C-22978r411915_chk

Open the Exchange Management Shell and enter the following command: Get-ExchangeServer | fl name, AdminDisplayVersion If the value of "AdminDisplayVersion" does not return the most current, approved service pack, this is a finding.

Fix: F-22967r411916_fix

Install the most current, approved service pack.

The application must configure malicious code protection mechanisms to perform periodic scans of the information system every seven days.

SI-3 - Medium - CCI-001241 - V-221264 - SV-221264r508017_rule

RMF Control

SI-3

Severity

CCI

CCI-001241

Version

EX16-ED-000720

Vuln IDs

V-221264
V-80607

Rule IDs

SV-221264r508017_rule
SV-95317

Malicious code protection mechanisms include, but are not limited, to anti-virus and malware detection software. In order to minimize potential negative impact to the organization that can be caused by malicious code, it is imperative that malicious code is identified and eradicated. Malicious code includes viruses, worms, trojan horses, and spyware. It is not enough to simply have the software installed; this software must periodically scan the system to search for malware on an organization-defined frequency. This requirement applies to applications providing malicious code protection.

Checks: C-22979r411918_chk

Open the Exchange Management Shell and enter the following command: Get-TransportAgent "Malware Agent" If the value of "Enabled" is set to "True", this is a finding.

Fix: F-22968r411919_fix

Open the Exchange Management Shell and enter the following command: & env:ExchangeInstallPath\Scripts\Disable-Antimalwarescanning.ps1

The application must configure malicious code protection mechanisms to perform periodic scans of the information system every seven days.

SI-3 - Medium - CCI-001241 - V-221265 - SV-221265r508017_rule

RMF Control

SI-3

Severity

CCI

CCI-001241

Version

EX16-ED-000730

Vuln IDs

V-221265
V-80609

Rule IDs

SV-221265r508017_rule
SV-95319

Checks: C-22980r411921_chk

Site must utilize an approved DoD third-party malicious code scanner. Consult with System Administrator to demonstrate the application being used to provide malicious code protection in the Exchange implementation. If System Administrator is unable to demonstrate a third-party malicious code protection application, this is a finding. If System Administrator is unaware of a third-party malicious code protection application, this is a finding.

Fix: F-22969r411922_fix

Following vendor best practice guidance, install and configure a third-party malicious code protection application.

The application must be configured to block and quarantine malicious code upon detection, then send an immediate alert to appropriate individuals.

SI-3 - Medium - CCI-001243 - V-221266 - SV-221266r508017_rule

RMF Control

SI-3

Severity

CCI

CCI-001243

Version

EX16-ED-000750

Vuln IDs

V-221266
V-80611

Rule IDs

SV-221266r508017_rule
SV-95321

Malicious code protection mechanisms include, but are not limited, to anti-virus and malware detection software. In order to minimize potential negative impact to the organization that can be caused by malicious code, it is imperative that malicious code is identified and eradicated. Applications providing this capability must be able to perform actions in response to detected malware. Responses include blocking, quarantining, deleting, and alerting. Other technology- or organization-specific responses may also be employed to satisfy this requirement. Malicious code includes viruses, worms, trojan horses, and spyware. This requirement applies to applications providing malicious code protection.

Checks: C-22981r411924_chk

Open the Exchange Management Shell and enter the following command: Get-TransportAgent "Malware Agent" If the value of "Enabled" is set to "True", this is a finding.

Fix: F-22970r411925_fix

Open the Exchange Management Shell and enter the following command: & env:ExchangeInstallPath\Scripts\Disable-Antimalwarescanning.ps1

The application must be configured to block and quarantine malicious code upon detection, then send an immediate alert to appropriate individuals.

SI-3 - Medium - CCI-001243 - V-221267 - SV-221267r508017_rule

RMF Control

SI-3

Severity

CCI

CCI-001243

Version

EX16-ED-000760

Vuln IDs

V-221267
V-80613

Rule IDs

SV-221267r508017_rule
SV-95323

Malicious code protection mechanisms include, but are not limited, to anti-virus and malware detection software. In order to minimize potential negative impact to the organization that can be caused by malicious code, it is imperative that malicious code is identified and eradicated. Applications providing this capability must be able to perform actions in response to detected malware. Responses include blocking, quarantining, deleting, and alerting. Other technology- or organization-specific responses may also be employed to satisfy this requirement. Malicious code includes viruses, worms, trojan horses, and spyware. This requirement applies to applications providing malicious code protection.

Checks: C-22982r411927_chk

Fix: F-22971r411928_fix

Following vendor best practice guidance, install and configure a third-party malicious code protection application.

The application must update malicious code protection mechanisms whenever new releases are available in accordance with organizational configuration management policy and procedures.

SI-3 - Medium - CCI-001240 - V-221268 - SV-221268r508017_rule

RMF Control

SI-3

Severity

CCI

CCI-001240

Version

EX16-ED-002400

Vuln IDs

V-221268
V-80615

Rule IDs

SV-221268r508017_rule
SV-95325

Malicious code includes viruses, worms, trojan horses, and spyware. The code provides the ability for a malicious user to read from and write to files and folders on a computer's hard drive. Malicious code may also be able to run and attach programs, which may allow the unauthorized distribution of malicious mobile code. Once this code is installed on endpoints within the network, unauthorized users may be able to breach firewalls and gain access to sensitive data. This requirement applies to applications providing malicious code protection. Malicious code protection mechanisms include, but are not limited, to, anti-virus and malware detection software. Malicious code protection mechanisms (including signature definitions and rule sets) must be updated when new releases are available.

Checks: C-22983r411930_chk

Open the Exchange Management Shell and enter the following command: Get-TransportAgent "Malware Agent" If the value of "Enabled" is set to "True", this is a finding.

Fix: F-22972r411931_fix

Open the Exchange Management Shell and enter the following command: & env:ExchangeInstallPath\Scripts\Disable-Antimalwarescanning.ps1

The application must update malicious code protection mechanisms whenever new releases are available in accordance with organizational configuration management policy and procedures.

SI-3 - Medium - CCI-001240 - V-221269 - SV-221269r508017_rule

RMF Control

SI-3

Severity

CCI

CCI-001240

Version

EX16-ED-002410

Vuln IDs

V-221269
V-80617

Rule IDs

SV-221269r508017_rule
SV-95327

Checks: C-22984r411933_chk

Fix: F-22973r411934_fix

Following vendor best practice guidance, install and configure a third-party malicious code protection application.

The applications built-in Malware Agent must be disabled.

SI-3 - Medium - CCI-001242 - V-221270 - SV-221270r508017_rule

RMF Control

SI-3

Severity

CCI

CCI-001242

Version

EX16-ED-003010

Vuln IDs

V-221270
V-80619

Rule IDs

SV-221270r508017_rule
SV-95329

Malicious code protection mechanisms include, but are not limited, to, anti-virus and malware detection software. In order to minimize potential negative impact to the organization that can be caused by malicious code, it is imperative that malicious code is identified and eradicated. Malicious code includes viruses, worms, trojan horses, and spyware. It is not enough to simply have the software installed; this software must periodically scan the system to search for malware on an organization-defined frequency. Exchange's built-in Malware Agent is not designed to address all malicious code protection workloads. This workload is best handled by third-party anti-virus and intrusion prevention software. Site must utilize an approved DoD scanner. Exchange Malware software has a limited scanning capability and does not scan files that are downloaded, opened, or executed.

Checks: C-22985r411936_chk

Open the Exchange Management Shell and enter the following command: Get-TransportAgent "Malware Agent" If the value of "Enabled" is set to "True", this is a finding.

Fix: F-22974r411937_fix

Open the Exchange Management Shell and enter the following command: & env:ExchangeInstallPath\Scripts\Disable-Antimalwarescanning.ps1

Added rules 69

Removed rules 70

Checks: C-22917r411732_chk

Fix: F-22906r411733_fix

Generate Mitigation Statement:

Checks: C-22918r411735_chk

Fix: F-22907r411736_fix

Generate Mitigation Statement:

Checks: C-22919r411738_chk

Fix: F-22908r411739_fix

Generate Mitigation Statement:

Checks: C-22920r411741_chk

Fix: F-22909r411742_fix

Generate Mitigation Statement:

Checks: C-22921r411744_chk

Fix: F-22910r411745_fix

Generate Mitigation Statement:

Checks: C-22922r411747_chk

Fix: F-22911r411748_fix

Generate Mitigation Statement:

Checks: C-22923r411750_chk

Fix: F-22912r411751_fix

Generate Mitigation Statement:

Checks: C-22924r411753_chk

Fix: F-22913r411754_fix

Generate Mitigation Statement:

Checks: C-22925r411756_chk

Fix: F-22914r411757_fix

Generate Mitigation Statement:

Checks: C-22926r411759_chk

Fix: F-22915r411760_fix

Generate Mitigation Statement:

Checks: C-22927r411762_chk

Fix: F-22916r411763_fix

Generate Mitigation Statement:

Checks: C-22928r411765_chk

Fix: F-22917r411766_fix

Generate Mitigation Statement:

Checks: C-22929r411768_chk

Fix: F-22918r411769_fix

Generate Mitigation Statement:

Checks: C-22930r411771_chk

Fix: F-22919r411772_fix

Generate Mitigation Statement:

Checks: C-22931r411774_chk

Fix: F-22920r411775_fix

Generate Mitigation Statement:

Checks: C-22932r411777_chk

Fix: F-22921r411778_fix

Generate Mitigation Statement:

Checks: C-22933r411780_chk

Fix: F-22922r411781_fix

Generate Mitigation Statement:

Checks: C-22934r411783_chk

Fix: F-22923r411784_fix

Generate Mitigation Statement:

Checks: C-22935r411786_chk

Fix: F-22924r411787_fix

Generate Mitigation Statement:

Checks: C-22936r411789_chk

Fix: F-22925r411790_fix

Generate Mitigation Statement:

Checks: C-22937r411792_chk

Fix: F-22926r411793_fix

Generate Mitigation Statement:

Checks: C-22938r411795_chk

Fix: F-22927r411796_fix

Generate Mitigation Statement:

Checks: C-22939r411798_chk

Fix: F-22928r411799_fix

Generate Mitigation Statement:

Checks: C-22940r411801_chk

Fix: F-22929r411802_fix

Generate Mitigation Statement:

Checks: C-22941r411804_chk

Fix: F-22930r411805_fix

Generate Mitigation Statement:

Checks: C-22942r495389_chk

Fix: F-22931r411808_fix

Generate Mitigation Statement: