Microsoft Defender Antivirus
TMA-DEFENDER-1.6.1.17
Ensure 'Configure Attack Surface Reduction rules: Set the state for each ASR rule' is set to 'c1db55ab-c21a-4637-bb3f- a12568109d35:2' or higher
Description
This rule provides an extra layer of protection against ransomware. It uses both client and cloud heuristics to determine whether a file resembles ransomware. This rule doesn't block files that have one or more of the following characteristics: - The file has already been found to be unharmful in the Microsoft cloud. - The file is a valid signed file. Rationale: This ASR rule can help an organization enhance its protection against ransomware by using both cloud and local heuristics. Audit reads the Group Policy registry value and prints 'compliant', 'unset' (policy not configured, reported as FAIL) or the non-compliant value. Registry value: HKLM\SOFTWARE\Policies\Microsoft\Windows Defender\Windows Defender Exploit Guard\ASR\Rules:c1db55ab-c21a-4637-bb3f-a12568109d35 (REG_SZ); compliant when it is 2 or 1.
How it is checked
Audit method: Windows registry
$v = (Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Windows Defender Exploit Guard\ASR\Rules' -Name 'c1db55ab-c21a-4637-bb3f-a12568109d35' -ErrorAction SilentlyContinue).'c1db55ab-c21a-4637-bb3f-a12568109d35'; if ($null -eq $v) { 'unset' } elseif (($null -ne $v -and @('2','1') -contains "$v")) { 'compliant' } else { "non-compliant: $v" }- Expected output
compliant
How it is fixed
Fix method: Guidance or infrastructure patch
Configure through Group Policy: Computer Configuration\Policies\Administrative Templates\Windows Components\Microsoft Defender Antivirus\Microsoft Defender Exploit Guard\Attack Surface Reduction\Configure Attack Surface Reduction rules: Set the state for each ASR rule = c1db55ab-c21a-4637-bb3f-a12568109d35 with a value of 2 or 1. Test in audit mode (2) first. Local alternative (writes Defender preferences, not the Group Policy value this audit reads): Add-MpPreference -AttackSurfaceReductionRules_Ids c1db55ab-c21a-4637-bb3f-a12568109d35 -AttackSurfaceReductionRules_Actions 2
Properties
- Operating systems
- Any
- Tags
- defenderantiviruscis-l1
- Reference
- CIS Microsoft Defender Antivirus Benchmark v1.0.0 - 1.6.1.17 Ensure 'Configure Attack Surface Reduction rules: Set the state for each ASR rule' is set to 'c1db55ab-c21a-4637-bb3f- a12568109d35:2' or higher
Check this host
Run this on a machine you are allowed to audit. The scan is read-only.
tmaegis scan --target defender