Malicious WARMCOOKIE DLL Execution from RtlUpd Path via rundll32

PremiumReviewedSigma · High · v1
Category
process_creation
Author
HuntRule
Published
2026-07-30
Updated
2026-08-28

ATT&CK techniques

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 detects rundll32.exe executing a DLL from the C:\ProgramData\RtlUpd directory, the fixed drop path and loader behavior of the WARMCOOKIE backdoor. The malware writes RtlUpd.dll to this ProgramData location and runs it via rundll32 to establish its foothold.

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Pivot detection · T1218.011 · 9 related

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