huntrule

Windows Registry: User Account Changed for FAX Service

Flags registry changes that alter the FAX service’s associated user account on Windows.

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 identifies when the user account associated with the Windows FAX service is changed via the registry. Attackers can use service logon account changes to redirect service execution and potentially support persistence or defense impairment. It relies on registry set telemetry targeting the FAX service ObjectName value under HKLM\System\CurrentControlSet\Services\Fax.

Reporting behind it

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Malicious WDigest UseLogonCredential Enabled for Cleartext Credential Theft (via registry_set)
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Windows Registry: User Account Changed for FAX Service
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.