huntrule

Windows Registry AMSI COM Server Hijacking via InProcServer32 CLSID Modification

Alerts on registry changes that alter an AMSI COM CLSID InProcServer32 entry to break AMSI loading.

FreeReviewedSigma · High · v1
Product
windows
Category
registry_set
Author
Nasreddine Bencherchali (Nextron Systems) (SigmaHQ), DRL 1.1
Published
2023-01-04
Updated
2026-07-30
AnalysisDetection

ATT&CK techniques

  1. Recon

  2. Resource Dev

  3. Initial Access

  4. Execution

  5. Persistence

  6. Priv Esc

  7. Defense Evasion

  8. Cred Access

  9. Discovery

  10. Lateral Movement

  11. Collection

  12. C2

  13. Exfiltration

  14. Impact

What it detects

This rule flags attempts to modify the InProcServer32 registry value for a specific AMSI-related COM CLSID, which can prevent AMSI from loading its COM server component. Attackers may use this defense-impairment technique to disrupt AMSI scanning functionality. The detection relies on registry set telemetry for the targeted CLSID InProcServer32 default value and excludes cases where the value points to %windir%\system32\amsi.dll.

Reporting behind it

Related detections9 linkedT1685 — drag to rearrange
Suspicious Vulnerable Intel Ethernet Driver Load for BYOVD via SCATTERED SPIDER (via driver_load)
Malicious Defender Disable And Executable Exclusion Via Registry
Malicious UAC Disable via EnableLUA Registry Modification (via registry_set)
Malicious AMSI and ETW Patching via PowerShell Script
Malicious PowMix AMSI Bypass via amsiInitFailed
Suspicious ThrottleStop Driver Abuse for Defense Evasion in Ransomware Attacks
Malicious Disabling of Microsoft Defender Real-Time Protection via SystemSettingsAdminFlows by DeadLock Ransomware
Suspicious Security Software Uninstallation via WMIC Product Call Uninstall (Chaos Ransomware)
Suspicious Security Product Uninstall via wmic product call uninstall
Windows Registry AMSI COM Server Hijacking via InProcServer32 CLSID Modification
Pivot detection · T1685 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.