Malicious regsvr32 DLL Execution with Custom Install Argument

ATT&CK techniques

Defense Evasion

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
- T1218.010Regsvr32
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects regsvr32 executed silently with the /n and /i install switches to register and pass a custom argument to a DLL, a technique observed in the AppleSeed triple-combo campaign that ran tripservice.dll with the marker /i:tgvyh. It captures signed-binary proxy execution used to run attacker DLL code while bypassing application controls. Detecting this is important because the combination of /s /n /i on regsvr32 rarely appears in legitimate software.

Reporting behind it

Related detections9 linkedT1218.010 — drag to rearrange

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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

Malicious regsvr32 DLL Execution with Custom Install Argument

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.

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