Identifier / Programs / Windows
fsi.exe
LOLBAS AWL Bypass 1 Sigma rule name it 1 ATT&CK technique 2 documented commands
How fsi.exe is abused
AWL Bypass T1059 Command and Scripting Interpreter
Each abuse is LOLBAS's category and the options and words it uses; the full write-up is on LOLBAS's page for fsi.exe.
2 documented commands
AWL Bypass T1059 Command and Scripting Interpreter User privileges
Execute F# code via script file
fsi.exe {PATH:.fsscript}Trips 1 Sigma rule: mediumUse of FSharp Interpreters by Christopher Peacock @SecurePeacock, SCYTHE @scythe_io
AWL Bypass T1059 Command and Scripting Interpreter User privileges
Execute F# code via interactive command line
fsi.exeTrips 1 Sigma rule: mediumUse of FSharp Interpreters by Christopher Peacock @SecurePeacock, SCYTHE @scythe_io
All 2 commands the identifier reads trip a Sigma process-creation rule. These commands and their descriptions are from LOLBAS’s entry for fsi.exe, by Jimmy (@bohops), at commit 2056cb766250 of 2026-09-26, under the GPL-3.0 and LOLBAS’s notice, with no warranty. Changed: Markdown is shown formatted. The source is in lolbas-gtfobins-commands.json.gz, and the full entry is on LOLBAS’s page for fsi.exe. The identifier reads each with LOLBAS’s placeholders filled in: a URL as https://example.com/file, a share as \\192.0.2.10\share\file, a path as C:\Data\file and a command as calc.exe.