SV-278649r1192810: Microsoft Defender AV must block untrusted and unsigned processes that run from USB. | Microsoft Defender Antivirus STIG SCAP Benchmark

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Assessment Title

Rule Text

Microsoft Defender AV must block untrusted and unsigned processes that run from USB.

Description

Discussion Text

This policy setting helps prevents unsigned or untrusted executable files from running from USB removable drives, including SD cards. Blocked file types include executable files (such as .exe, .dll, or .scr).

How this relates to the STIG checklist: STIG vs SCAP benchmark.

IA Controls

NIST SP 800-53

Not mappedCCI-001170

References

DPMS Target Microsoft Defender Antivirus DISA DPMS Target Microsoft Defender Antivirus 3985

SCC Automation Reference

The reconstructed evaluation script behind this rule's OVAL check(s) — every module a compound check combines, with this rule's own concrete values and DISA's SCC tool's real per-module mechanism curated from static teardown of SCC releases.

# Windows PowerShell
# Reconstructed from oval:mil.disa.stig.windowsdefav:def:278649
# Microsoft Defender AV must block untrusted and unsigned processes that run from USB.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# b2b3f03d-6a65-4f7b-a9c7-1c7ef74a9ba4 == 1
# registry_object (registry_test)
function test_1 {
  return (((@{String='reg_sz';ExpandString='reg_expand_sz';Binary='reg_binary';DWord='reg_dword';MultiString='reg_multi_sz';QWord='reg_qword';None='reg_none'}[(Get-Item -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows Defender\Windows Defender Exploit Guard\ASR\Rules').GetValueKind('b2b3f03d-6a65-4f7b-a9c7-1c7ef74a9ba4').ToString()]) -eq 'reg_sz') -and (((Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows Defender\Windows Defender Exploit Guard\ASR\Rules' -Name 'b2b3f03d-6a65-4f7b-a9c7-1c7ef74a9ba4' -ErrorAction SilentlyContinue) | Select-Object -ExpandProperty 'b2b3f03d-6a65-4f7b-a9c7-1c7ef74a9ba4') -eq '1'))
}

if (test_1) {
  Write-Output "PASS"
} else {
  Write-Output "FAIL"
}

Assessment Script Powered by AISyntax-verified

A standalone PowerShell script to assess this control automatically. Review before running it in your environment.

Syntax-checked as valid PowerShell. Not executed here — running it for real needs the actual ms_defender_antivirus target this check assesses.

# OVAL Definition: oval:mil.disa.stig.windowsdefav:def:278649
$regPath = "HKLM:\Software\Policies\Microsoft\Windows Defender\Windows Defender Exploit Guard\ASR\Rules"
$regKey = "b2b3f03d-6a65-4f7b-a9c7-1c7ef74a9ba4"
$regValue = 1
if (Test-Path $regPath -ErrorAction SilentlyContinue -and (Get-ItemProperty -Path $regPath -Name $regKey -ErrorAction SilentlyContinue).$regKey -eq $regValue) { Write-Output "PASS"; Exit 0 } else { Write-Output "FAIL"; Exit 1 }

Remediation

Set the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> Microsoft Defender Exploit Guard >> Attack Surface Reduction >> Configure Attack Surface Reduction rules to "Enabled".

Under the policy option "Set the state for each ASR rule:", then click "Show".

Enter GUID "b2b3f03d-6a65-4f7b-a9c7-1c7ef74a9ba4" in the "Value Name" column.

Enter "1" in the "Value" column.