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Windows Image Load of clfsw32.dll by svchost.exe indicating PRIVATELOG usage

Alert on svchost.exe loading clfsw32.dll, a rarely observed Windows image load pattern consistent with PRIVATELOG.

FreeReviewedSigma · High · v5
Product
windows
Category
image_load
Author
Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
Published
2021-09-07
Updated
2026-07-31
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 specific Windows image load sequence where svchost.exe loads clfsw32.dll. Such module loading patterns are rarely observed under normal conditions and can indicate tool-driven stealth or misuse of legitimate components. The detection relies on image load telemetry that records the full image path for both the loading process (Image) and the loaded module (ImageLoaded).

Reporting behind it

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Suspicious SmallTiger Backdoor DLL Load via Image Load
Suspicious svchost Execution With Anomalous Arguments via DeedRAT (via process_creation)
Windows Image Load of clfsw32.dll by svchost.exe indicating PRIVATELOG usage
Pivot detection · T1055 · 9 related

Changelog

v5
  1. v5
    Candidate ingested via manual entry.2026-07-31
  2. v4
    Candidate ingested via manual entry.2026-07-31
  3. v3
    Candidate ingested via manual entry.2026-07-31
  4. v2
    Candidate ingested via manual entry.2026-07-31
  5. v1
    No changelog recorded for this version.2026-07-30

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