Malicious AMSI and ETW Patching via PowerShell Script

ATT&CK techniques

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects PowerShell script content that references AmsiScanBuffer or EtwEventWrite in order to patch the Antimalware Scan Interface and Event Tracing for Windows, an in-memory evasion step UAT-11795 performs before injecting the Starland RAT as reported by Cisco Talos. Tampering with these logging and scanning interfaces blinds defenses. Detecting the patch strings exposes active defense evasion in the loader.

Reporting behind it

Related detections9 linkedT1685 — drag to rearrange

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Malicious Windows Defender Tampering via Set-MpPreference and Add-MpPreference (via ps_script)

Suspicious PowerShell AMSI Bypass via 8220 Gang Hadooken Loader

Malicious Microsoft Defender Services Stopped via sc.exe

Suspicious Microsoft Defender Definitions Removed via MpCmdRun

Suspicious Defender Behavior Monitoring Disable via PowerShell (via process_creation)

Suspicious Windows Defender Real-Time Monitoring Disable (via process_creation)

Malicious Microsoft Defender Real-Time Monitoring Disabled via Set-MpPreference (via process_creation)

Malicious AMSI and ETW Patching via PowerShell Script

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.

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