huntrule

Windows Process Creation: rundll32.exe Command Line Invoking .sys Files

Flags Windows rundll32.exe executions whose command line references .sys file patterns.

FreeReviewedSigma · High · v1
Product
windows
Category
process_creation
Author
Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
Published
2021-03-05
Updated
2026-07-30
AnalysisDetection

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 identifies Windows process creation events where rundll32.exe is launched with a command line that includes a .sys file pattern ('.sys,' or '.sys '). Attackers may use rundll32 to load or reference system driver files as part of stealthy execution, making this string-based behavior a useful indicator of suspicious rundll32 usage. It relies on process creation telemetry with access to the full command line.

Reporting behind it

Related detections9 linkedT1218.011 — drag to rearrange
Malicious DLL Execution With Non Standard Extension via rundll32
Andromeda Loader Execution via Rundll32 Desktop.ini Ordinal
Suspicious rundll32 Execution of sqlite3 DLL by Ordinal with TLB Argument
Malicious Zardoor Backdoor Execution via rundll32 (via process_creation)
Malicious Rundll32 Loading an Export From a User Path (via process_creation)
Renamed Regsvr32 or Rundll32 Loading a DLL With a Non-Standard Extension (via process_creation)
Malicious Rundll32 DllRegisterServer Execution From a User-Writable Path (via process_creation)
IMEEX Framework DLL Execution via Rundll32 Loading imaadp (via process_creation)
Suspicious Persistence via pcalua Launching rundll32 Control_RunDLL
Windows Process Creation: rundll32.exe Command Line Invoking .sys Files
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.