Microsoft Windows Defender Antivirus STIG: WNDF-AV-000037

Check: WNDF-AV-000037 (in versions v2 r2 through v1 r2)

Title

Windows Defender AV must be configured to block execution of potentially obfuscated scripts. (Cat II impact)

Discussion

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.

Check Content

This setting is applicable starting with v1709 of Windows 10, it is NA for prior versions. Verify 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" is set to "Enabled”. Click ‘Show...’. Verify the rule ID in the Value name column and the desired state in the Value column is set as follows: Value name: 5BEB7EFE-FD9A-4556-801D-275E5FFC04CC Value: 1 Procedure: Use the Windows Registry Editor to navigate to the following key: HKLM\Software\Policies\Microsoft\Windows Defender\Windows Defender Exploit Guard\ASR\Rules Criteria: If the value “5BEB7EFE-FD9A-4556-801D-275E5FFC04CC” is REG_SZ = 1, this is not a finding.

Fix Text

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”.

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CCIs

CCIs tied to check.
Number Definition
CCI-001170

The information system prevents the automatic execution of mobile code in organization-defined software applications.

Controls

Controls tied to check. These are derived from the CCIs shown above.
Number Title
SC-18 (4)

Prevent Automatic Execution