huntrule

Windows Process Creation: regsvr32 Invoked to Load .ocx from AppData Roaming

Flags regsvr32 /s /i loading an .ocx from AppData\Roaming on Windows, a stealthy code-loading technique.

FreeReviewedSigma · Critical · v5
Product
windows
Category
process_creation
Author
Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
Published
2020-07-10
Updated
2026-07-31
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 flags Windows process creation events where regsvr32 is executed with parameters that include /s /i, a path under AppData\Roaming\, and a .ocx extension. That pattern is consistent with signed-binary execution used to load and run external component files from user-writable locations. The detection relies on process command-line telemetry containing these specific substrings.

Reporting behind it

Related detections9 linkedT1218.011 — drag to rearrange
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
Suspicious Rundll32 Executing DLL Start Export With Control Flags
Windows Process Creation: regsvr32 Invoked to Load .ocx from AppData Roaming
Pivot detection · T1218.011 · 9 related

Changelog

v5
  1. v5
    Candidate ingested via manual entry.2026-07-31
  2. v4
    Candidate ingested via manual entry.2026-07-31
  3. v3
    Candidate ingested via manual entry.2026-07-31
  4. v2
    Candidate ingested via manual entry.2026-07-31
  5. v1
    No changelog recorded for this version.2026-07-30

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