Suspicious Csi.exe Usage
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…
Description
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'
Detection logic
Detection requirements
- Platform
- LinuxmacOSNetwork DevicesSaaSWindows
The rule states no platform. This is derived from the 2 ATT&CK techniques it maps to.
- Log source product
- windows
- Log source category
- process_creation
Known benign triggers
- Legitimate usage by software developers
MITRE ATT&CK mappings
0 exclusive techniques.This is coverage no other published rule has; it is not this rule's total technique count.
References
| Reference | Cited by |
|---|---|
| enigma0x3.net/2016/11/21/bypassing-application-whitelisting-by-using-rcsi-exe/ | Only this detection cites it |
| lolbas-project.github.io/lolbas/OtherMSBinaries/Csi/ | 2 |
| lolbas-project.github.io/lolbas/OtherMSBinaries/Rcsi/ | Only this detection cites it |
| twitter.com/Z3Jpa29z/status/1317545798981324801 | Only this detection cites it |
From the source
- At source
- Open at source
- Upstream identifier
- 40b95d31-1afc-469e-8d34-9a3a667d058e
- Tagged by the source as
- attack.executionattack.lateral-movementattack.stealth
Licence
- Published under
- Detection Rule License 1.1Read the licence
- Attribution
- Required
Authorship
- Written by
- Published
- Aug 26, 2026
- Version
- 1