Renamed Regsvr32 or Rundll32 Loading a DLL With a Non-Standard Extension (via process_creation)

ATT&CK techniques

Defense Evasion

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
- T1036.008Masquerade File Type
- T1218.011Rundll32
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects regsvr32 or rundll32 loading a module that carries a disguised or non-standard extension such as .dat, .tmp, .png or .log from a user-writable directory, a masquerading pattern used by loaders like Qbot to hide their DLL payload. Proxy execution of renamed DLLs is documented in the Red Canary Threat Detection Report as a way to defeat extension-based controls. Detecting these disguised module loads surfaces the payload execution.

Reporting behind it

Related detections9 linkedT1218.011 — drag to rearrange

Malicious Rundll32 Loading an Export From a User Path (via process_creation)

Malicious Rundll32 DllRegisterServer Execution From a User-Writable Path (via process_creation)

Masquerading sLoad Ramnit Loader Execution via PowerShell Running a Masqueraded Log Script (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

Suspicious Rundll32 Execution of Timestamp-Named DLL

Suspicious Rundll32 Loading DLL from LocalAppData with Short Export (via process_creation)

Malicious Word Spawning Rundll32 Loading DLL from Roaming Word Folder

Renamed Regsvr32 or Rundll32 Loading a DLL With a Non-Standard Extension (via process_creation)

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.

Full detection rule

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