huntrule

Windows: Suspicious Execution of CSharp Interactive Console via PowerShell

Alerts when PowerShell launches csi.exe, indicating possible interactive .NET code execution.

FreeReviewedSigma · High · v2
Product
windows
Category
process_creation
Author
Michael R. (@nahamike01) (SigmaHQ), DRL 1.1
Published
2020-03-08
Updated
2026-07-31
AnalysisDetection

ATT&CK techniques

Execution → 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 identifies process creation where the C# interactive console (csi.exe) is launched by PowerShell-related parent processes. Attackers may use interactive .NET/C# tooling to rapidly execute code and evade traditional scripting or deployment paths. The detection relies on Windows process creation telemetry, matching the child executable name and the parent executable path endings (PowerShell/pwsh/Powershell ISE).

Reporting behind it

Related detections9 linkedT1127 — drag to rearrange
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Suspicious aspnet_compiler.exe Execution from User or Temp Paths on Windows
Windows: Detect kavremover-related LOLBIN command-line usage
Windows node.exe Execution with -e/--eval and suspicious child process usage
Windows: Process creation involving VSIISExeLauncher.exe with -p and -a arguments
Windows Process Creation: Mftrace.exe Child Process Execution
Windows Process Creation: Remote.exe Execution
Windows: Suspicious Execution of CSharp Interactive Console via PowerShell
Pivot detection · T1127 · 9 related

Changelog

v2
  1. v2
    Candidate ingested via manual entry.2026-07-31
  2. 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.