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Windows UAC Bypass via NTFS Reparse Point: wusa.exe DLL Hijacking Process Behavior

Alerts on high-integrity wusa.exe launched from Temp update.msu with a dism.exe parent showing DismHost activity.

FreeReviewedSigma · High · v1
Product
windows
Category
process_creation
Author
Christian Burkard (Nextron Systems) (SigmaHQ), DRL 1.1
Published
2021-08-30
Updated
2026-07-30
AnalysisDetection

ATT&CK techniques

Priv Esc → Defense Evasion

  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 a process-creation sequence consistent with a UAC bypass technique that uses an NTFS reparse point and wusa.exe DLL hijacking. It matches wusa.exe executions with specific command-line patterns and high/system integrity context, as well as a parent dism.exe invocation indicative of package/handler staging. Telemetry required is Windows process creation with full command lines and process integrity level data.

Reporting behind it

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Malicious UAC Bypass via explorer.exe NOUACCHECK Argument
Suspicious UAC Bypass via ms-settings Shell Command Hijack (via registry_set)
Windows UAC Bypass via NTFS Reparse Point: wusa.exe DLL Hijacking Process Behavior
Pivot detection · T1548.002 · 9 related

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