huntrule

Windows Process CommandLine contains -export dll_u (DLL export function load)

Flags Windows processes that invoke a DLL export function named dll_u via command-line export arguments.

FreeReviewedSigma · Critical · v5
Product
windows
Category
process_creation
Author
Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
Published
2019-03-04
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 matches Windows process command lines that include the DLL export function name "dll_u" via the "-export" parameter. Attackers may use DLL export function invocation patterns to load or execute code in a stealthy way, blending into legitimate-looking command-line activity. Detection relies on process creation telemetry with the full CommandLine field.

Reporting behind it

Related detections9 linkedT1218.011 — drag to rearrange
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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 CommandLine contains -export dll_u (DLL export function load)
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.