Sigma rule: Suspicious Csi.exe Usage

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-c18e9f1bd1aa, updated 2022-07-11T00:00:00.000Z.

Rule

Title
Suspicious Csi.exe Usage
Status
test
Level
medium
Author
Konstantin Grishchenko, oscd.community
Date
2020-10-17
Modified
2022-07-11
File
rules/windows/process_creation/proc_creation_win_csi_execution.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Csi.exe is a signed binary from Microsoft that comes with Visual Studio and provides C# interactive capabilities. It can be used to run C# code from a file passed as a parameter in command line. Early version of this utility provided with Microsoft “Roslyn” Community Technology Preview was named 'rcsi.exe'

Log source

product
windows
category
process_creation

Detection

selection_img:
    - Image|endswith:
          - '\csi.exe'
          - '\rcsi.exe'
    - OriginalFileName:
          - 'csi.exe'
          - 'rcsi.exe'
selection_cli:
    Company: 'Microsoft Corporation'
condition: all of selection*

False positives (as the rule lists them)

  • Legitimate usage by software developers

Tags

  • attack.lateral-movement
  • attack.execution
  • attack.stealth
  • attack.t1072
  • attack.t1218

MITRE ATT&CK ids this rule names

References

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_csi_execution.yml

Sources and licences

  • SigmaHQ

    "Suspicious Csi.exe Usage" by Konstantin Grishchenko, oscd.community (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_csi_execution.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

Cite this page

Dragons Eye Ransomware Tracker, "Sigma rule: Suspicious Csi.exe Usage",
entity page, dataset version ref-c18e9f1bd1aa, updated 2022-07-11T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/40b95d31-1afc-469e-8d34-9a3a667d058e (accessed 2026-11-03).
Underlying source: SigmaHQ rule 40b95d31-1afc-469e-8d34-9a3a667d058e, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.