huntrule

Windows Registry Fax Device Provider ImageName changed to load external DLL

Alerts when Fax Device Providers\ImageName registry values change in a way consistent with DLL-loading persistence.

FreeReviewedSigma · High · v1
Product
windows
Category
registry_set
Author
frack113 (SigmaHQ), DRL 1.1
Published
2022-07-17
Updated
2026-07-30
AnalysisDetection

ATT&CK techniques

Persistence → 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 registry changes under the Fax device provider path where an ImageName value is set, indicating a possible Fax DLL load persistence mechanism upon service restart. Attackers may use this to cause a service to load a chosen DLL, helping maintain execution across restarts while blending into expected system component configuration. Detection relies on Windows registry set telemetry matching the targeted Fax provider subkeys and ImageName entries, while excluding cases where the ImageName points to %systemroot%\system32\fxst30.dll.

Reporting behind it

Related detections9 linkedT1112 — drag to rearrange
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Malicious WDigest Credential Caching Enabled via Registry (via registry_set)
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Malicious Gh0stBins RAT Registry Marker HHClient
Suspicious PebbleDash C2 Configuration Stored Under WMI Security Key (via registry_set)
Suspicious WDigest UseLogonCredential Enablement for Plaintext Credential Theft (via registry_set)
Windows Registry Fax Device Provider ImageName changed to load external DLL
Pivot detection · T1112 · 9 related

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