huntrule

Windows Process Creation: NirCmd runasSystem CommandLine Usage

Alerts on NirCmd being used to run commands as LocalSystem based on the process command line.

FreeReviewedSigma · High · v1
Product
windows
Category
process_creation
Author
Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems) (SigmaHQ), DRL 1.1
Published
2022-01-24
Updated
2026-07-30
AnalysisDetection

ATT&CK techniques

Execution

  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 command line contains the ' runassystem ' string, indicating use of NirCmd to execute commands in the LocalSystem context. Attackers can leverage this capability to elevate execution privileges and run actions with high authority. The detection relies on process creation telemetry and the recorded command line content.

Reporting behind it

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Suspicious PSexec Application Execution (via process_creation)
Malicious Metasploit PsExec Named Pipe Command Execution
Malicious PsExec Service Installation via PSEXESVC
Malicious NotPetya Payload Execution via Rundll32 Ordinal Export from Windows Directory
Suspicious Lateral Movement via PsExec Service (via process_creation)
Possible PsExec Remote Service Installation with Randomly Named Service (via security)
Windows Process Creation: NirCmd runasSystem CommandLine Usage
Pivot detection · T1569.002 · 9 related

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