huntrule

Malicious PXA Stealer Persistence via Windows Update Service Run Key (via registry_set)

PremiumReviewedSigma · High · v1
Product
windows
Category
registry_set
Author
HuntRule
Published
2026-10-27
Updated
2026-10-27
AnalysisDetection

ATT&CK techniques

Persistence → Priv Esc

  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 detects PXA Stealer establishing persistence by writing a Run key named Windows Update Service that launches a payload from the public user directory. The value masquerades as a Windows update while pointing at an attacker binary under C drive Users Public. Legitimate autostart entries rarely execute from that location.

Reporting behind it

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Suspicious HTA File Dropped into Startup Folder
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Malicious Registry Run Key Persistence Using Scarlet Goldfinch OFFICE and DIVXX Values (via registry_set)
Suspicious Internet Shortcut URL File Registered for Run Key Persistence (via registry_set)
Malicious Run Key Persistence Named SystemAgentService
Malicious PXA Stealer Persistence via Windows Update Service Run Key (via registry_set)
Pivot detection · T1547.001 · 9 related

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