View SCAP - MS Windows Defender Antivirus Security Technical Implementation Guide V1R6

c

Windows Defender AV must be configured to block the Potentially Unwanted Application (PUA) feature.

RMF Control: SI-3
Severity: High
CCI: CCI-001243
Version: WNDF-AV-000001
Vuln IDs: V-75147
Rule IDs: SV-89827r3_rule

After enabling this feature, PUA protection blocking takes effect on endpoint clients after the next signature update or computer restart. Signature updates take place daily under typical circumstances. PUA will be blocked and automatically quarantined.

Fix: F-81759r4_fix

Set the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Windows Defender Antivirus >> "Configure Detection for Potentially Unwanted Applications" to "Enabled" and "Block".

b

Windows Defender AV must be configured to automatically take action on all detected tasks.

RMF Control: SI-3
Severity: Medium
CCI: CCI-001243
Version: WNDF-AV-000003
Vuln IDs: V-75151
Rule IDs: SV-89831r2_rule

This policy setting allows you to configure whether Windows Defender automatically takes action on all detected threats. The action to be taken on a particular threat is determined by the combination of the policy-defined action user-defined action and the signature-defined action. If you enable this policy setting Windows Defender does not automatically take action on the detected threats but prompts users to choose from the actions available for each threat. If you disable or do not configure this policy setting Windows Defender automatically takes action on all detected threats after a nonconfigurable delay of approximately five seconds.

Fix: F-81763r2_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> "Turn off routine remediation" to "Disabled" or "Not Configured".

c

Windows Defender AV must be configured to run and scan for malware and other potentially unwanted software.

RMF Control: SI-3
Severity: High
CCI: CCI-001242
Version: WNDF-AV-000004
Vuln IDs: V-75153
Rule IDs: SV-89833r5_rule

This policy setting turns off Windows Defender Antivirus. If you enable this policy setting Windows Defender Antivirus does not run and computers are not scanned for malware or other potentially unwanted software. When the setting is Disabled and a third-party antivirus solution is installed, the two applications can both simultaneously try to protect the system. The two AV solutions both attempt to quarantine the same threat and will fight for access to delete the file. Users will see conflicts and the system may lock up until the two solutions finish processing. When the setting is Not Configured and a third-party antivirus solution is installed, both applications co-exist on the system without conflicts. Defender Antivirus will automatically disable itself and will enable if the third-party solution stops functioning. When the setting is Not Configured and Defender Antivirus is the only AV solution, Defender AV will run (default state) and receive definition updates. An administrator account is needed to turn off the service. A standard user cannot disable the service.

Fix: F-81765r5_fix

For Windows 10: Set the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Windows Defender Antivirus set "Turn off Windows Defender Antivirus" to "Not Configured". For Windows 2016/Windows 2019: Use the following PowerShell cmdlet to uninstall Windows Defender AV on Windows 2016/Windows 2019: Uninstall-WindowsFeature -Name Windows-Defender

b

Windows Defender AV must be configured to not exclude files for scanning.

RMF Control: SI-3
Severity: Medium
CCI: CCI-001242
Version: WNDF-AV-000005
Vuln IDs: V-75155
Rule IDs: SV-89835r2_rule

This policy setting allows you to disable scheduled and real-time scanning for files under the paths specified or for the fully qualified resources specified. Paths should be added under the Options for this setting. Each entry must be listed as a name value pair where the name should be a string representation of a path or a fully qualified resource name. As an example a path might be defined as: "c:\Windows" to exclude all files in this directory. A fully qualified resource name might be defined as: "C:\Windows\App.exe". The value is not used and it is recommended that this be set to 0.

Fix: F-81767r2_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Exclusions -> "Path Exclusions" to "Disabled" or "Not Configured".

b

Windows Defender AV must be configured to not exclude files opened by specified processes.

RMF Control: SI-3
Severity: Medium
CCI: CCI-001242
Version: WNDF-AV-000006
Vuln IDs: V-75157
Rule IDs: SV-89837r2_rule

This policy setting allows you to disable scheduled and real-time scanning for any file opened by any of the specified processes. The process itself will not be excluded. To exclude the process use the Path exclusion. Processes should be added under the Options for this setting. Each entry must be listed as a name value pair where the name should be a string representation of the path to the process image. Note that only executables can be excluded. For example a process might be defined as: "c:\windows\app.exe". The value is not used and it is recommended that this be set to 0.

Fix: F-81769r2_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Exclusions -> "Process Exclusions" to "Disabled" or "Not Configured".

b

Windows Defender AV must be configured to enable the Automatic Exclusions feature.

RMF Control: SI-3
Severity: Medium
CCI: CCI-001242
Version: WNDF-AV-000007
Vuln IDs: V-75159
Rule IDs: SV-89839r2_rule

Allows an administrator to specify if Automatic Exclusions feature for Server SKUs should be turned off.

Fix: F-81771r1_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Exclusions -> "Turn off Auto Exclusions" to "Disabled".

b

Windows Defender AV must be configured to disable local setting override for reporting to Microsoft MAPS.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001170
Version: WNDF-AV-000008
Vuln IDs: V-75161
Rule IDs: SV-89841r2_rule

This policy setting configures a local override for the configuration to join Microsoft MAPS. This setting can only be set by Group Policy. If you enable this setting the local preference setting will take priority over Group Policy. If you disable or do not configure this setting Group Policy will take priority over the local preference setting.

Fix: F-81773r4_fix

This is applicable to unclassified systems, for other systems this is NA. Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> MAPS -> "Configure local setting override for reporting to Microsoft MAPS" to "Disabled" or "Not Configured".

b

Windows Defender AV must be configured to check in real time with MAPS before content is run or accessed.

RMF Control: SI-3
Severity: Medium
CCI: CCI-001242
Version: WNDF-AV-000009
Vuln IDs: V-75163
Rule IDs: SV-89843r2_rule

This feature ensures the device checks in real time with the Microsoft Active Protection Service (MAPS) before allowing certain content to be run or accessed. If this feature is disabled the check will not occur which will lower the protection state of the device. Enabled - The Block at First Sight setting is turned on. Disabled - The Block at First Sight setting is turned off. This feature requires these Group Policy settings to be set as follows: MAPS -> The "Join Microsoft MAPS" must be enabled or the "Block at First Sight" feature will not function. MAPS -> The "Send file samples when further analysis is required" should be set to 1 (Send safe samples) or 3 (Send all samples). Setting to 0 (Always Prompt) will lower the protection state of the device. Setting to 2 (Never send) means the "Block at First Sight" feature will not function. Real-time Protection -> The "Scan all downloaded files and attachments" policy must be enabled or the "Block at First Sight" feature will not function. Real-time Protection -> Do not enable the "Turn off real-time protection" policy or the "Block at First Sight" feature will not function.

Fix: F-81775r3_fix

This is applicable to unclassified systems, for other systems this is NA. Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> MAPS -> "Configure the 'Block at First Sight' feature" to "Enabled".

b

Windows Defender AV must be configured to join Microsoft MAPS.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001170
Version: WNDF-AV-000010
Vuln IDs: V-75167
Rule IDs: SV-89847r6_rule

This policy setting allows you to join Microsoft MAPS. Microsoft MAPS is the online community that helps you choose how to respond to potential threats. The community also helps stop the spread of new malicious software infections. You can choose to send basic or additional information about detected software. Additional information helps Microsoft create new definitions and help it to protect your computer. This information can include things like location of detected items on your computer if harmful software was removed. The information will be automatically collected and sent. In some instances personal information might unintentionally be sent to Microsoft. However Microsoft will not use this information to identify you or contact you. Possible options are: (0x0) Disabled (default) (0x1) Basic membership (0x2) Advanced membership Basic membership will send basic information to Microsoft about software that has been detected including where the software came from the actions that you apply or that are applied automatically and whether the actions were successful. Advanced membership in addition to basic information will send more information to Microsoft about malicious software spyware and potentially unwanted software including the location of the software file names how the software operates and how it has impacted your computer. If you enable this setting you will join Microsoft MAPS with the membership specified. If you disable or do not configure this setting you will not join Microsoft MAPS. In Windows 10 Basic membership is no longer available so setting the value to 1 or 2 enrolls the device into Advanced membership.

Fix: F-81779r8_fix

This is applicable to unclassified systems, for other systems this is NA. Set the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Windows Defender Antivirus >> MAPS >> "Join Microsoft MAPS" to "Enabled" and select "Advanced MAPS" from the drop down box.

b

Windows Defender AV must be configured to only send safe samples for MAPS telemetry.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001170
Version: WNDF-AV-000011
Vuln IDs: V-75207
Rule IDs: SV-89887r3_rule

This policy setting configures behavior of samples submission when opt-in for MAPS telemetry is set. Possible options are: (0x0) Always prompt (0x1) Send safe samples automatically (0x2) Never send (0x3) Send all samples automatically.

Fix: F-81859r4_fix

This is applicable to unclassified systems, for other systems this is NA. Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> MAPS -> "Send file samples when further analysis is required" to "Enabled" and select "Send safe samples" from the drop down box.

b

Windows Defender AV must be configured for protocol recognition for network protection.

RMF Control: SI-3
Severity: Medium
CCI: CCI-001242
Version: WNDF-AV-000012
Vuln IDs: V-75209
Rule IDs: SV-89889r2_rule

This policy setting allows you to configure protocol recognition for network protection against exploits of known vulnerabilities. If you enable or do not configure this setting protocol recognition will be enabled. If you disable this setting protocol recognition will be disabled.

Fix: F-81819r2_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Network Inspection System -> "Turn on protocol recognition" to "Enabled" or "Not Configured".

b

Windows Defender AV must be configured to not allow local override of monitoring for file and program activity.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001695
Version: WNDF-AV-000013
Vuln IDs: V-75211
Rule IDs: SV-89891r2_rule

This policy setting configures a local override for the configuration of monitoring for file and program activity on your computer. This setting can only be set by Group Policy. If you enable this setting the local preference setting will take priority over Group Policy. If you disable or do not configure this setting Group Policy will take priority over the local preference setting.

Fix: F-81821r2_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Real-time Protection -> "Configure local setting override for monitoring file and program activity on your computer" to "Disabled" or "Not Configured".

b

Windows Defender AV must be configured to not allow override of monitoring for incoming and outgoing file activity.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001695
Version: WNDF-AV-000014
Vuln IDs: V-75213
Rule IDs: SV-89893r2_rule

This policy setting configures a local override for the configuration of monitoring for incoming and outgoing file activity. This setting can only be set by Group Policy. If you enable this setting the local preference setting will take priority over Group Policy. If you disable or do not configure this setting Group Policy will take priority over the local preference setting.

Fix: F-81823r2_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Real-time Protection -> "Configure local setting override for monitoring for incoming and outgoing file activity" to "Disabled" or "Not Configured".

b

Windows Defender AV must be configured to not allow override of scanning for downloaded files and attachments.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001169
Version: WNDF-AV-000015
Vuln IDs: V-75215
Rule IDs: SV-89895r2_rule

This policy setting configures a local override for the configuration of scanning for all downloaded files and attachments. This setting can only be set by Group Policy. If you enable this setting the local preference setting will take priority over Group Policy. If you disable or do not configure this setting Group Policy will take priority over the local preference setting.

Fix: F-81825r2_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Real-time Protection -> "Configure local setting override for scanning all downloaded files and attachments" to "Disabled" or "Not Configured".

b

Windows Defender AV must be configured to not allow override of behavior monitoring.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001170
Version: WNDF-AV-000016
Vuln IDs: V-75217
Rule IDs: SV-89897r2_rule

This policy setting configures a local override for the configuration of behavior monitoring. This setting can only be set by Group Policy. If you enable this setting the local preference setting will take priority over Group Policy. If you disable or do not configure this setting Group Policy will take priority over the local preference setting.

Fix: F-81827r2_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Real-time Protection -> "Configure local setting override for turn on behavior monitoring" to "Disabled" or "Not Configured".

b

Windows Defender AV Group Policy settings must take priority over the local preference settings.

RMF Control: SI-3
Severity: Medium
CCI: CCI-001242
Version: WNDF-AV-000017
Vuln IDs: V-75219
Rule IDs: SV-89899r2_rule

This policy setting configures a local override for the configuration to turn on real-time protection. This setting can only be set by Group Policy. If you enable this setting the local preference setting will take priority over Group Policy. If you disable or do not configure this setting Group Policy will take priority over the local preference setting.

Fix: F-81829r2_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Real-time Protection -> "Configure local setting override to turn on real-time protection" to "Disabled" or "Not Configured".

b

Windows Defender AV must monitor for incoming and outgoing files.

RMF Control: SI-3
Severity: Medium
CCI: CCI-001242
Version: WNDF-AV-000018
Vuln IDs: V-75221
Rule IDs: SV-89901r2_rule

This policy setting allows you to configure monitoring for incoming and outgoing files without having to turn off monitoring entirely. It is recommended for use on servers where there is a lot of incoming and outgoing file activity but for performance reasons need to have scanning disabled for a particular scan direction. The appropriate configuration should be evaluated based on the server role. Note that this configuration is only honored for NTFS volumes. For any other file system type full monitoring of file and program activity will be present on those volumes. The options for this setting are mutually exclusive: 0 = Scan incoming and outgoing files (default) 1 = Scan incoming files only 2 = Scan outgoing files only Any other value or if the value does not exist resolves to the default (0). If you enable this setting the specified type of monitoring will be enabled. If you disable or do not configure this setting monitoring for incoming and outgoing files will be enabled.

Fix: F-81831r2_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Real-time Protection -> "Configure monitoring for incoming and outgoing file and program activity" to "Disabled" or "Not Configured".

b

Windows Defender AV must be configured to monitor for file and program activity.

RMF Control: SI-3
Severity: Medium
CCI: CCI-001242
Version: WNDF-AV-000019
Vuln IDs: V-75223
Rule IDs: SV-89903r2_rule

This policy setting allows you to configure monitoring for file and program activity. If you enable or do not configure this setting monitoring for file and program activity will be enabled. If you disable this setting monitoring for file and program activity will be disabled.

Fix: F-81833r2_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Real-time Protection -> "Monitor file and program activity on your computer" to "Enabled" or "Not Configured".

b

Windows Defender AV must be configured to scan all downloaded files and attachments.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001169
Version: WNDF-AV-000020
Vuln IDs: V-75225
Rule IDs: SV-89905r2_rule

This policy setting allows you to configure scanning for all downloaded files and attachments. If you enable or do not configure this setting scanning for all downloaded files and attachments will be enabled. If you disable this setting scanning for all downloaded files and attachments will be disabled.

Fix: F-81835r2_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Real-time Protection -> "Scan all downloaded files and attachments" to "Enabled" or "Not Configured".

b

Windows Defender AV must be configured to always enable real-time protection.

RMF Control: SI-3
Severity: Medium
CCI: CCI-001242
Version: WNDF-AV-000021
Vuln IDs: V-75227
Rule IDs: SV-89907r2_rule

This policy setting turns off real-time protection prompts for known malware detection. Windows Defender Antivirus alerts you when malware or potentially unwanted software attempts to install itself or to run on your computer. If you enable this policy setting Windows Defender Antivirus will not prompt users to take actions on malware detections. If you disable or do not configure this policy setting Windows Defender Antivirus will prompt users to take actions on malware detections.

Fix: F-81837r2_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Real-time Protection -> "Turn off real-time protection" to "Disabled" or "Not Configured".

b

Windows Defender AV must be configured to enable behavior monitoring.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001170
Version: WNDF-AV-000022
Vuln IDs: V-75229
Rule IDs: SV-89909r2_rule

This policy setting allows you to configure behavior monitoring. If you enable or do not configure this setting behavior monitoring will be enabled. If you disable this setting behavior monitoring will be disabled.

Fix: F-81839r2_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Real-time Protection -> "Turn on behavior monitoring" to "Enabled " or "Not Configured".

b

Windows Defender AV must be configured to process scanning when real-time protection is enabled.

RMF Control: SI-3
Severity: Medium
CCI: CCI-001242
Version: WNDF-AV-000023
Vuln IDs: V-75231
Rule IDs: SV-89911r2_rule

This policy setting allows you to configure process scanning when real-time protection is turned on. This helps to catch malware which could start when real-time protection is turned off. If you enable or do not configure this setting a process scan will be initiated when real-time protection is turned on. If you disable this setting a process scan will not be initiated when real-time protection is turned on.

Fix: F-81841r2_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Real-time Protection -> Turn on process scanning whenever real-time protection is enabled to "Enabled" or "Not Configured".

b

Windows Defender AV must be configured to scan archive files.

RMF Control: SI-3
Severity: Medium
CCI: CCI-001242
Version: WNDF-AV-000024
Vuln IDs: V-75233
Rule IDs: SV-89913r2_rule

This policy setting allows you to configure scans for malicious software and unwanted software in archive files such as .ZIP or .CAB files. If you enable or do not configure this setting archive files will be scanned. If you disable this setting archive files will not be scanned.

Fix: F-81843r2_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Scan -> "Scan archive files" to "Enabled " or "Not Configured".

b

Windows Defender AV must be configured to scan removable drives.

RMF Control: MA-3
Severity: Medium
CCI: CCI-000870
Version: WNDF-AV-000025
Vuln IDs: V-75235
Rule IDs: SV-89915r2_rule

This policy setting allows you to manage whether or not to scan for malicious software and unwanted software in the contents of removable drives such as USB flash drives when running a full scan. If you enable this setting removable drives will be scanned during any type of scan. If you disable or do not configure this setting removable drives will not be scanned during a full scan. Removable drives may still be scanned during quick scan and custom scan.

Fix: F-81845r3_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Scan -> "Scan removable drives" to "Enabled".

b

Windows Defender AV must be configured to perform a weekly scheduled scan.

RMF Control: SI-3
Severity: Medium
CCI: CCI-001241
Version: WNDF-AV-000026
Vuln IDs: V-75237
Rule IDs: SV-89917r2_rule

This policy setting allows you to specify the day of the week on which to perform a scheduled scan. The scan can also be configured to run every day or to never run at all. This setting can be configured with the following ordinal number values: (0x0) Every Day (0x1) Sunday (0x2) Monday (0x3) Tuesday (0x4) Wednesday (0x5) Thursday (0x6) Friday (0x7) Saturday (0x8) Never (default) If you enable this setting a scheduled scan will run at the frequency specified. If you disable or do not configure this setting a scheduled scan will run at a default frequency.

Fix: F-81847r2_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Scan -> "Specify the day of the week to run a scheduled scan" to "Enabled " and select anything other than "Never" in the drop down box.

b

Windows Defender AV must be configured to turn on e-mail scanning.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001170
Version: WNDF-AV-000027
Vuln IDs: V-75239
Rule IDs: SV-89919r2_rule

This policy setting allows you to configure e-mail scanning. When e-mail scanning is enabled the engine will parse the mailbox and mail files according to their specific format in order to analyze the mail bodies and attachments. Several e-mail formats are currently supported for example: pst (Outlook) dbx mbx mime (Outlook Express) binhex (Mac). If you enable this setting e-mail scanning will be enabled. If you disable or do not configure this setting e-mail scanning will be disabled.

Fix: F-81849r2_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Scan -> "Turn on e-mail scanning" to "Enabled".

c

Windows Defender AV spyware definition age must not exceed 7 days.

RMF Control: SI-3
Severity: High
CCI: CCI-001240
Version: WNDF-AV-000028
Vuln IDs: V-75241
Rule IDs: SV-89921r2_rule

This policy setting allows you to define the number of days that must pass before spyware definitions are considered out of date. If definitions are determined to be out of date this state may trigger several additional actions including falling back to an alternative update source or displaying a warning icon in the user interface. By default this value is set to 14 days. If you enable this setting spyware definitions will be considered out of date after the number of days specified have passed without an update. If you disable or do not configure this setting spyware definitions will be considered out of date after the default number of days have passed without an update.

Fix: F-81851r2_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Signature Updates -> "Define the number of days before spyware definitions are considered out of date" to "Enabled" and select "7" or less in the drop down box. Do not select a value of 0. This disables the option.

c

Windows Defender AV virus definition age must not exceed 7 days.

RMF Control: SI-3
Severity: High
CCI: CCI-001240
Version: WNDF-AV-000029
Vuln IDs: V-75243
Rule IDs: SV-89923r2_rule

This policy setting allows you to define the number of days that must pass before virus definitions are considered out of date. If definitions are determined to be out of date this state may trigger several additional actions including falling back to an alternative update source or displaying a warning icon in the user interface. By default this value is set to 14 days. If you enable this setting virus definitions will be considered out of date after the number of days specified have passed without an update. If you disable or do not configure this setting virus definitions will be considered out of date after the default number of days have passed without an update.

Fix: F-81853r2_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Signature Updates -> "Define the number of days before virus definitions are considered out of date" to "Enabled" and select "7" or less in the drop down box. Do not select a value of 0. This disables the option.

b

Windows Defender AV must be configured to check for definition updates daily.

RMF Control: SI-8
Severity: Medium
CCI: CCI-001308
Version: WNDF-AV-000030
Vuln IDs: V-75245
Rule IDs: SV-89925r2_rule

This policy setting allows you to specify the day of the week on which to check for definition updates. The check can also be configured to run every day or to never run at all. This setting can be configured with the following ordinal number values: (0x0) Every Day (default) (0x1) Sunday (0x2) Monday (0x3) Tuesday (0x4) Wednesday (0x5) Thursday (0x6) Friday (0x7) Saturday (0x8) Never If you enable this setting the check for definition updates will occur at the frequency specified. If you disable or do not configure this setting the check for definition updates will occur at a default frequency.

Fix: F-81855r3_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Signature Updates -> "Specify the day of the week to check for definition updates" to "Enabled" and select "Every Day" in the drop down box.

b

Windows Defender AV must be configured for automatic remediation action to be taken for threat alert level Severe.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001662
Version: WNDF-AV-000031
Vuln IDs: V-75247
Rule IDs: SV-89927r3_rule

This policy setting allows you to customize which automatic remediation action will be taken for each threat alert level. Threat alert levels should be added under the Options for this setting. Each entry must be listed as a name value pair. The name defines a threat alert level. The value contains the action ID for the remediation action that should be taken. Valid threat alert levels are: 1 = Low 2 = Medium 4 = High 5 = Severe Valid remediation action values are: 2 = Quarantine 3 = Remove 6 = Ignore

Fix: F-81857r3_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Threats -> "Specify threat alert levels at which default action should not be taken when detected" to "Enabled". Select the “Show…” option box and enter "5” in the ‘Value name’ field and enter “2" in the ‘Value’ field.

b

Windows Defender AV must be configured to block executable content from email client and webmail.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001170
Version: WNDF-AV-000032
Vuln IDs: V-77965
Rule IDs: SV-92661r1_rule

This rule blocks the following file types from being run or launched from an email seen in either Microsoft Outlook or webmail (such as Gmail.com or Outlook.com): Executable files (such as .exe, .dll, or .scr) Script files (such as a PowerShell .ps, VisualBasic .vbs, or JavaScript .js file) Script archive files

Fix: F-84677r1_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Windows Defender Exploit Guard -> Attack Surface Reduction -> "Configure Attack Surface Reduction rules" to "Enabled”. Click ‘Show...’. Set the Value name to “BE9BA2D9-53EA-4CDC-84E5-9B1EEEE46550” and the Value to “1”.

b

Windows Defender AV must be configured block Office applications from creating child processes.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001170
Version: WNDF-AV-000033
Vuln IDs: V-77967
Rule IDs: SV-92663r1_rule

Office apps, such as Word or Excel, will not be allowed to create child processes. This is a typical malware behavior, especially for macro-based attacks that attempt to use Office apps to launch or download malicious executables.

Fix: F-84679r1_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Windows Defender Exploit Guard -> Attack Surface Reduction -> "Configure Attack Surface Reduction rules" to "Enabled”. Click ‘Show...’. Set the Value name to “D4F940AB-401B-4EFC-AADC-AD5F3C50688A” and the Value to “1”.

b

Windows Defender AV must be configured block Office applications from creating executable content.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001170
Version: WNDF-AV-000034
Vuln IDs: V-77969
Rule IDs: SV-92665r1_rule

This rule targets typical behaviors used by suspicious and malicious add-ons and scripts (extensions) that create or launch executable files. This is a typical malware technique. Extensions will be blocked from being used by Office apps. Typically these extensions use the Windows Scripting Host (.wsh files) to run scripts that automate certain tasks or provide user-created add-on features.

Fix: F-84681r1_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Windows Defender Exploit Guard -> Attack Surface Reduction -> "Configure Attack Surface Reduction rules" to "Enabled”. Click ‘Show...’. Set the Value name to “3B576869-A4EC-4529-8536-B80A7769E899” and the Value to “1”.

b

Windows Defender AV must be configured to block Office applications from injecting into other processes.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001170
Version: WNDF-AV-000035
Vuln IDs: V-77971
Rule IDs: SV-92667r1_rule

Office apps, such as Word, Excel, or PowerPoint, will not be able to inject code into other processes. This is typically used by malware to run malicious code in an attempt to hide the activity from antivirus scanning engines.

Fix: F-84683r1_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Windows Defender Exploit Guard -> Attack Surface Reduction -> "Configure Attack Surface Reduction rules" to "Enabled”. Click ‘Show...’. Set the Value name to “75668C1F-73B5-4CF0-BB93-3ECF5CB7CC84” and the Value to “1”.

b

Windows Defender AV must be configured to impede JavaScript and VBScript to launch executables.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001170
Version: WNDF-AV-000036
Vuln IDs: V-77973
Rule IDs: SV-92669r1_rule

JavaScript and VBScript scripts can be used by malware to launch other malicious apps. This rule prevents these scripts from being allowed to launch apps, thus preventing malicious use of the scripts to spread malware and infect machines.

Fix: F-84685r1_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Windows Defender Exploit Guard -> Attack Surface Reduction -> "Configure Attack Surface Reduction rules" to "Enabled”. Click ‘Show...’. Set the Value name to “D3E037E1-3EB8-44C8-A917-57927947596D” and the Value to “1”.

b

Windows Defender AV must be configured to block execution of potentially obfuscated scripts.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001170
Version: WNDF-AV-000037
Vuln IDs: V-77975
Rule IDs: SV-92671r1_rule

Malware and other threats can attempt to obfuscate or hide their malicious code in some script files. This rule prevents scripts that appear to be obfuscated from running. It uses the AntiMalwareScanInterface (AMSI) to determine if a script is potentially obfuscated, and then blocks such a script, or blocks scripts when an attempt is made to access them.

Fix: F-84687r1_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Windows Defender Exploit Guard -> Attack Surface Reduction -> "Configure Attack Surface Reduction rules" to "Enabled”. Click ‘Show...’. Set the Value name to “5BEB7EFE-FD9A-4556-801D-275E5FFC04CC” and the Value to “1”.

b

Windows Defender AV must be configured to block Win32 imports from macro code in Office.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001170
Version: WNDF-AV-000038
Vuln IDs: V-77977
Rule IDs: SV-92673r1_rule

This rule blocks potentially malicious behavior by not allowing macro code to execute routines in the Win 32 dynamic link library (DLL).

Fix: F-84689r1_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Windows Defender Exploit Guard -> Attack Surface Reduction -> "Configure Attack Surface Reduction rules" to "Enabled”. Click ‘Show...’. Set the Value name to “92E97FA1-2EDF-4476-BDD6-9DD0B4DDDC7B” and the Value to “1”.

b

Windows Defender AV must be configured to prevent user and apps from accessing dangerous websites.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001170
Version: WNDF-AV-000039
Vuln IDs: V-77979
Rule IDs: SV-92675r1_rule

Enable Windows Defender Exploit Guard network protection to prevent employees from using any application to access dangerous domains that may host phishing scams exploit-hosting sites and other malicious content on the Internet.

Fix: F-84691r1_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Windows Defender Exploit Guard -> Network Protection -> "Prevent users and apps from accessing dangerous websites" to "Enabled” and select “Block" in the drop down box.

b

Windows Defender AV must be configured for automatic remediation action to be taken for threat alert level High.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001662
Version: WNDF-AV-000040
Vuln IDs: V-79965
Rule IDs: SV-94669r1_rule

This policy setting allows you to customize which automatic remediation action will be taken for each threat alert level. Threat alert levels should be added under the Options for this setting. Each entry must be listed as a name value pair. The name defines a threat alert level. The value contains the action ID for the remediation action that should be taken. Valid threat alert levels are: 1 = Low 2 = Medium 4 = High 5 = Severe Valid remediation action values are: 2 = Quarantine 3 = Remove 6 = Ignore

Fix: F-86769r1_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Threats -> "Specify threat alert levels at which default action should not be taken when detected" to "Enabled". Select the “Show…” option box and enter "4” in the ‘Value name’ field and enter “2" in the ‘Value’ field.

b

Windows Defender AV must be configured for automatic remediation action to be taken for threat alert level Medium.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001662
Version: WNDF-AV-000041
Vuln IDs: V-79967
Rule IDs: SV-94671r1_rule

This policy setting allows you to customize which automatic remediation action will be taken for each threat alert level. Threat alert levels should be added under the Options for this setting. Each entry must be listed as a name value pair. The name defines a threat alert level. The value contains the action ID for the remediation action that should be taken. Valid threat alert levels are: 1 = Low 2 = Medium 4 = High 5 = Severe Valid remediation action values are: 2 = Quarantine 3 = Remove 6 = Ignore

Fix: F-86771r1_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Threats -> "Specify threat alert levels at which default action should not be taken when detected" to "Enabled". Select the “Show…” option box and enter "2” in the ‘Value name’ field and enter “2" in the ‘Value’ field.

b

Windows Defender AV must be configured for automatic remediation action to be taken for threat alert level Low.

RMF Control: SC-18
Severity: Medium
CCI: CCI-001662
Version: WNDF-AV-000042
Vuln IDs: V-79971
Rule IDs: SV-94675r1_rule

This policy setting allows you to customize which automatic remediation action will be taken for each threat alert level. Threat alert levels should be added under the Options for this setting. Each entry must be listed as a name value pair. The name defines a threat alert level. The value contains the action ID for the remediation action that should be taken. Valid threat alert levels are: 1 = Low 2 = Medium 4 = High 5 = Severe Valid remediation action values are: 2 = Quarantine 3 = Remove 6 = Ignore

Fix: F-86775r1_fix

Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Threats -> "Specify threat alert levels at which default action should not be taken when detected" to "Enabled". Select the “Show…” option box and enter "1” in the ‘Value name’ field and enter “2" in the ‘Value’ field.