Suspicious Windows Defender Exclusion Added for Entire Windows Directory

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 Add-MpPreference adding a Defender path exclusion for the broad C:\WINDOWS directory, an impairment technique used by the Nezha threat actor tool. Excluding the entire Windows directory blinds antivirus to malware staged in system paths. This overly broad exclusion is rarely legitimate and indicates deliberate defense evasion.

Reporting behind it

Related detections9 linkedT1685 — drag to rearrange

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Malicious Vulnerable Driver Load via TfSysMon.sys BYOVD (via driver_load)

Suspicious Defendnot Antivirus Disabling Component Dropped in ProgramData (via file_event)

Suspicious Windows Defender Exclusion Added for Entire Windows Directory

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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