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 Lunar Spider Loader Execution via rundll32 (via process_creation)
Malicious SYSTEM Persistence via Scheduled Task Running rundll32 at Startup (via process_creation)
Malicious Rundll32 Executing Image File as DLL
Suspicious Scheduled Task Executing Rundll32 DLL Export by Ordinal
Malicious Renamed Rundll32 Copied to Temp via Xcopy
Suspicious rundll32 Executing DLL from ProgramData (via process_creation)
Suspicious Rundll32 Loading DLL From Public or ProgramData Path via Process Creation (via process_creation)
Malicious LSASS Credential Dump via Rundll32 Comsvcs MiniDump via Process Creation (via process_creation)
Suspicious Rundll32 Execution Without a DLL Reference via Process Creation (via process_creation)
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.