Malicious AMSI Bypass via PowerShell Reflection (via ps_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 attempting to disable the Antimalware Scan Interface by patching AmsiUtils fields such as amsiInitFailed. The ClearFake variant runs an AMSI bypass before decrypting its AES payload so in-memory scanning is suppressed. Manipulating AMSI internals from a script is a strong signal of malicious execution.

Reporting behind it

Related detections9 linkedT1685 — drag to rearrange

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Malicious BYOVD EDR Kill via Renamed GMER Driver by Agonizing Serpens

Malicious AMSI Bypass via PowerShell Reflection (via ps_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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