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Windows regsvr32 Usage of /i Without /n Flag

Alerts on regsvr32.exe invocations using /i: without the usually paired /n flag.

FreeReviewedSigma · Medium · v1
Product
windows
Category
process_creation
Author
Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
Published
2019-07-13
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 flags Windows process creation events where the image path ends with regsvr32.exe and the command line contains the /i flag while the /n flag is not present. Attackers may use regsvr32 with atypical flag combinations to execute actions stealthily, so unusual parameter usage can be an early signal. The detection relies on process creation telemetry including the process image name and the full command line.

Reporting behind it

Related detections9 linkedT1218.010 — drag to rearrange
Malicious Regsvr32 ShellExec_RunDLL Proxy Execution (via process_creation)
Suspicious DLL Execution via Regsvr32 DllInstall of dat File
Malicious Xctdoor XcLoader Execution via Regsvr32 AppX Path Abuse (via process_creation)
Malicious Office Application Loading a User-Path DLL via Regsvr32 or Rundll32 (via process_creation)
Masquerading SSLoad PhantomLoader DLL Execution via Regsvr32 Silent Load from AppData (via process_creation)
Malicious Kimsuky AlphaSeed Payload Execution via Regsvr32 Loading edge dat (via process_creation)
Malicious Regsvr32 Executing DLL From Windows Temp
HttpSpy Payload Registration via Regsvr32 of Non-DLL File (via process_creation)
Malicious regsvr32 Scriptlet Execution via scrobj.dll
Windows regsvr32 Usage of /i Without /n Flag
Pivot detection · T1218.010 · 9 related

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