Phoenix Studio
Convert indexed Sigma rules into analyst-ready detections.
This studio is built around Phoenix's own rule corpus, not a blank editor. Search by title or rule id, choose a live sigma-cli backend, then reveal pipelines only when you actually need them.
Indexed Rules
3,707
Ready to search
Backends
17
Live from sigconverter.io
CLI Versions
10
Newest: 2.0.2
Translation Workspace
Shape the rule before it leaves Phoenix
Tune Translation
Active Rule
Use of FSharp Interpreters
Target Profile
Splunk
Splunk SPL & tstats data model queries
Format Mode
Default
Plain SPL queries
Conversion Output
Use of FSharp Interpreters
Using Splunk · Default · sigma-cli 2.0.2
Translation controls
Adjust the rule on the left, then regenerate when you want a fresh backend-native query.
BackendSplunkFormatDefaultVersion2.0.2
title: Use of FSharp Interpreters
id: b96b2031-7c17-4473-afe7-a30ce714db29
status: test
description: |
Detects the execution of FSharp Interpreters "FsiAnyCpu.exe" and "FSi.exe"
Both can be used for AWL bypass and to execute F# code via scripts or inline.
references:
- https://learn.microsoft.com/en-us/windows/security/application-security/application-control/windows-defender-application-control/design/applications-that-can-bypass-wdac
- https://bohops.com/2020/11/02/exploring-the-wdac-microsoft-recommended-block-rules-part-ii-wfc-fsi/
- https://lolbas-project.github.io/lolbas/OtherMSBinaries/FsiAnyCpu/
- https://lolbas-project.github.io/lolbas/OtherMSBinaries/Fsi/
author: Christopher Peacock @SecurePeacock, SCYTHE @scythe_io
date: 2022-06-02
modified: 2024-04-23
tags:
- attack.execution
- attack.t1059
logsource:
category: process_creation
product: windows
detection:
selection:
- Image|endswith:
- '\fsi.exe'
- '\fsianycpu.exe'
- OriginalFileName:
- 'fsi.exe'
- 'fsianycpu.exe'
condition: selection
falsepositives:
- Legitimate use by a software developer.
level: medium
CLI command
Copy the exact command to reproduce this translation locally.
sigma convert --without-pipeline -t splunk -f default rules/windows/process_creation/proc_creation_win_fsi_fsharp_code_execution.yml