Microsoft Exchange 2016 Edge Transport Server Security Technical Implementation Guide

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: [email protected]

Details

Version / Release: V1R5

Published: 2020-06-17

Updated At: 2020-08-15 20:23:07

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Drop CKL or SCAP (XCCDF) results here.

    Vuln Rule Version CCI Severity Title Description Status Finding Details Comments
    SV-95195r1_rule EX16-ED-000010 CCI-000054 MEDIUM Exchange must limit the Receive connector timeout. 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.
    SV-95197r1_rule EX16-ED-000020 CCI-000213 MEDIUM Exchange servers must use approved DoD certificates. 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 cont
    SV-95199r1_rule EX16-ED-000030 CCI-001368 MEDIUM Exchange must have accepted domains configured. 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.
    SV-95201r2_rule EX16-ED-000040 CCI-001368 MEDIUM Exchange must have auto-forwarding of email to remote domains disabled or restricted. 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
    SV-95203r1_rule EX16-ED-000050 CCI-001368 MEDIUM Exchange external Receive connectors must be domain secure-enabled. 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 fo
    SV-95205r1_rule EX16-ED-000060 CCI-000169 MEDIUM The Exchange email Diagnostic log level must be set to the lowest level. 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
    SV-95207r1_rule EX16-ED-000070 CCI-000169 MEDIUM Exchange Connectivity logging must be enabled. 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 defa
    SV-95209r1_rule EX16-ED-000080 CCI-000154 MEDIUM Exchange Queue monitoring must be configured with threshold and action. 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
    SV-95211r1_rule EX16-ED-000090 CCI-000381 MEDIUM Exchange must not send Customer Experience reports to Microsoft. 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
    SV-95213r1_rule EX16-ED-000100 CCI-000162 MEDIUM Exchange Audit data must be protected against unauthorized access (read access). 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 availabl
    SV-95215r1_rule EX16-ED-000110 CCI-000381 MEDIUM Exchange Send Fatal Errors to Microsoft must be disabled. 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
    SV-95217r1_rule EX16-ED-000120 CCI-000163 MEDIUM Exchange audit data must be protected against unauthorized access for modification. 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 availabl
    SV-95219r1_rule EX16-ED-000130 CCI-000164 MEDIUM Exchange audit data must be protected against unauthorized access for deletion. 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 availabl
    SV-95221r1_rule EX16-ED-000140 CCI-001348 MEDIUM Exchange audit data must be on separate partitions. 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 expl
    SV-95223r1_rule EX16-ED-000150 CCI-001749 MEDIUM The Exchange local machine policy must require signed scripts. 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.
    SV-95225r1_rule EX16-ED-000160 CCI-001178 MEDIUM Exchange Internet-facing Send connectors must specify a Smart Host. 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
    SV-95227r1_rule EX16-ED-000170 CCI-001184 MEDIUM Exchange internal Send connectors must use domain security (mutual authentication Transport Layer Security). 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 fo
    SV-95229r1_rule EX16-ED-000180 CCI-001184 MEDIUM Exchange Internet-facing Receive connectors must offer Transport Layer Security (TLS) before using basic authentication. 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 eavesdr
    SV-95231r1_rule EX16-ED-000190 CCI-001095 MEDIUM Exchange Outbound Connection Timeout must be 10 minutes or less. 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
    SV-95233r1_rule EX16-ED-000200 CCI-001095 MEDIUM Exchange Outbound Connection Limit per Domain Count must be controlled. 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 C
    SV-95235r1_rule EX16-ED-000230 CCI-001095 LOW Exchange Send connector connections count must be limited. 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 l
    SV-95237r1_rule EX16-ED-000240 CCI-001095 LOW Exchange message size restrictions must be controlled on Send connectors. 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 strateg
    SV-95239r1_rule EX16-ED-000250 CCI-001095 LOW Exchange Send connectors delivery retries must be controlled. 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 gen
    SV-95241r1_rule EX16-ED-000260 CCI-001095 LOW Exchange Send connectors must be clearly named. 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. Collective
    SV-95243r1_rule EX16-ED-000270 CCI-001095 MEDIUM Exchange Receive connector Maximum Hop Count must be 60. 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 I
    SV-95245r2_rule EX16-ED-000280 CCI-001095 LOW Exchange Receive connectors must be clearly named. 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. Collect
    SV-95247r1_rule EX16-ED-000290 CCI-001095 LOW Exchange Receive connectors must control the number of recipients chunked on a single message. 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 strateg
    SV-95249r1_rule EX16-ED-000300 CCI-001095 MEDIUM Exchange Receive connectors must control the number of recipients per message. 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 thro
    SV-95251r1_rule EX16-ED-000310 CCI-001095 LOW The Exchange Internet Receive connector connections count must be set to default. 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 simultaneou
    SV-95253r1_rule EX16-ED-000320 CCI-001095 LOW Exchange Message size restrictions must be controlled on Receive connectors. 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 strate
    SV-95255r1_rule EX16-ED-000330 CCI-001308 MEDIUM Exchange messages with a blank sender field must be rejected. 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 fie
    SV-95257r1_rule EX16-ED-000340 CCI-001308 MEDIUM Exchange messages with a blank sender field must be filtered. 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 fie
    SV-95259r2_rule EX16-ED-000350 CCI-001308 MEDIUM Exchange filtered messages must be archived. 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 fo
    SV-95261r2_rule EX16-ED-000360 CCI-001308 MEDIUM The Exchange Sender filter must block unaccepted domains. 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 i
    SV-95263r2_rule EX16-ED-000370 CCI-001308 MEDIUM Exchange nonexistent recipients must not be blocked. 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 mai
    SV-95265r2_rule EX16-ED-000380 CCI-001308 MEDIUM The Exchange Sender Reputation filter must be enabled. 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 tha
    SV-95267r2_rule EX16-ED-000390 CCI-001308 MEDIUM The Exchange Sender Reputation filter must identify the spam block level. 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 tha
    SV-95269r2_rule EX16-ED-000400 CCI-001308 MEDIUM Exchange Attachment filtering must remove undesirable attachments by file type. 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 fo
    SV-95271r2_rule EX16-ED-000410 CCI-001308 MEDIUM The Exchange Spam Evaluation filter must be enabled. 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 ve
    SV-95273r1_rule EX16-ED-000420 CCI-001308 MEDIUM The Exchange Block List service provider must be identified. 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 th
    SV-95275r2_rule EX16-ED-000430 CCI-001308 MEDIUM Exchange messages with a malformed From address must be rejected. 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 Se
    SV-95277r1_rule EX16-ED-000470 CCI-001308 MEDIUM The Exchange Recipient filter must be enabled. 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 evaluat
    SV-95279r1_rule EX16-ED-000480 CCI-001308 MEDIUM The Exchange tarpitting interval must be set. 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 comm
    SV-95281r1_rule EX16-ED-000490 CCI-001308 MEDIUM Exchange internal Receive connectors must not allow anonymous connections. 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 n
    SV-95283r1_rule EX16-ED-000500 CCI-001308 MEDIUM Exchange Simple Mail Transfer Protocol (SMTP) IP Allow List entries must be empty. 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 evaluat
    SV-95285r1_rule EX16-ED-000510 CCI-001308 MEDIUM The Exchange Simple Mail Transfer Protocol (SMTP) IP Allow List Connection filter must be enabled. 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 evaluat
    SV-95287r1_rule EX16-ED-000520 CCI-001308 MEDIUM The Exchange Simple Mail Transfer Protocol (SMTP) Sender filter must be enabled. 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 evalua
    SV-95289r1_rule EX16-ED-000530 CCI-001308 MEDIUM Exchange must have antispam filtering installed. 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 d
    SV-95291r1_rule EX16-ED-000540 CCI-001308 MEDIUM Exchange must have antispam filtering enabled. 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 d
    SV-95293r1_rule EX16-ED-000550 CCI-001308 MEDIUM Exchange must have antispam filtering configured. 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 sc
    SV-95295r2_rule EX16-ED-000560 CCI-001308 MEDIUM Exchange Sender Identification Framework must be enabled. 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 authen
    SV-95297r3_rule EX16-ED-000570 CCI-001308 HIGH Exchange must strip hyperlink email sources from non-.mil domains. 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 n
    SV-95299r1_rule EX16-ED-000580 CCI-001812 MEDIUM The Exchange application directory must be protected from unauthorized access. 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 w
    SV-95301r1_rule EX16-ED-000590 CCI-001813 MEDIUM The Exchange software baseline copy must exist. 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
    SV-95303r1_rule EX16-ED-000610 CCI-001762 MEDIUM Exchange services must be documented and unnecessary services must be removed or disabled. 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 ou
    SV-95305r1_rule EX16-ED-000620 CCI-002530 MEDIUM Exchange software must be installed on a separate partition from the OS. 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 ot
    SV-95307r1_rule EX16-ED-000630 CCI-002385 MEDIUM The Exchange SMTP automated banner response must not reveal server details. 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
    SV-95309r1_rule EX16-ED-000660 CCI-002418 HIGH Exchange must provide redundancy. 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 ap
    SV-95311r1_rule EX16-ED-000670 CCI-002385 MEDIUM Exchange internal Send connectors must use an authentication level. 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 co
    SV-95313r2_rule EX16-ED-000690 CCI-002418 HIGH Exchange internal Send connectors must require encryption. 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 co
    SV-95315r1_rule EX16-ED-000700 CCI-002605 MEDIUM Exchange must have the most current, approved service pack installed. 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 acti
    SV-95317r1_rule EX16-ED-000720 CCI-001241 MEDIUM The application must configure malicious code protection mechanisms to perform periodic scans of the information system every seven days. 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
    SV-95319r1_rule EX16-ED-000730 CCI-001241 MEDIUM The application must configure malicious code protection mechanisms to perform periodic scans of the information system every seven days. 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
    SV-95321r1_rule EX16-ED-000750 CCI-001243 MEDIUM The application must be configured to block and quarantine malicious code upon detection, then send an immediate alert to appropriate individuals. 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
    SV-95323r1_rule EX16-ED-000760 CCI-001243 MEDIUM The application must be configured to block and quarantine malicious code upon detection, then send an immediate alert to appropriate individuals. 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
    SV-95325r1_rule EX16-ED-002400 CCI-001240 MEDIUM The application must update malicious code protection mechanisms whenever new releases are available in accordance with organizational configuration management policy and procedures. 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, whic
    SV-95327r1_rule EX16-ED-002410 CCI-001240 MEDIUM The application must update malicious code protection mechanisms whenever new releases are available in accordance with organizational configuration management policy and procedures. 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, whic
    SV-95329r1_rule EX16-ED-003010 CCI-001242 MEDIUM The applications built-in Malware Agent must be disabled. 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
    SV-95331r1_rule EX16-ED-003020 CCI-001242 MEDIUM A DoD-approved third-party Exchange-aware malicious code protection application must be implemented. 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
    SV-95463r1_rule EX16-ED-000680 CCI-002418 HIGH Exchange internal Receive connectors must require encryption. 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.