Sigma rule: Process Proxy Execution Via Squirrel.EXE

Rule

Title

Process Proxy Execution Via Squirrel.EXE

Status

test

Level

medium

Author

Nasreddine Bencherchali (Nextron Systems), Karneades / Markus Neis, Jonhnathan Ribeiro, oscd.community

Date

2022-06-09

Modified

2025-10-07

File

rules/windows/process_creation/proc_creation_win_squirrel_proxy_execution.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects the usage of the "Squirrel.exe" binary to execute arbitrary processes. This binary is part of multiple Electron based software installations (Slack, Teams, Discord, etc.)

Log source

product

windows

category

process_creation

Detection

selection_img:
    Image|endswith:
        - '\squirrel.exe'
        - '\update.exe'
selection_exec:
    CommandLine|contains:
        - '--processStart'
        - '--processStartAndWait'
        - '--createShortcut'
filter_optional_discord:
    CommandLine|contains|all:
        - ':\Users\'
        - '\AppData\Local\Discord\Update.exe'
        - 'Discord.exe'
    CommandLine|contains:
        - '--createShortcut'
        - '--processStart'
filter_optional_github_desktop:
    CommandLine|contains|all:
        - ':\Users\'
        - '\AppData\Local\GitHubDesktop\Update.exe'
        - 'GitHubDesktop.exe'
    CommandLine|contains:
        - '--createShortcut'
        - '--processStartAndWait'
filter_optional_teams:
    CommandLine|contains|all:
        - ':\Users\'
        - '\AppData\Local\Microsoft\Teams\Update.exe'
        - 'Teams.exe'
    CommandLine|contains:
        - '--processStart'
        - '--createShortcut'
filter_optional_yammer:
    CommandLine|contains|all:
        - ':\Users\'
        - '\AppData\Local\yammerdesktop\Update.exe'
        - 'Yammer.exe'
    CommandLine|contains:
        - '--processStart'
        - '--createShortcut'
condition: all of selection_* and not 1 of filter_optional_*

False positives (as the rule lists them)

• Expected FP with some Electron based applications such as (1Clipboard, Beaker Browser, Caret, Discord, GitHub Desktop, etc.)

Tags

• attack.execution
• attack.stealth
• attack.t1218

MITRE ATT&CK ids this rule names

• T1218

Related rules

• 1e75c1cc-c5d4-42aa-ac3d-91b0b68b3b4c (similar)
• fa4b21c9-0057-4493-b289-2556416ae4d7 (obsolete)

References

• https://lolbas-project.github.io/lolbas/OtherMSBinaries/Squirrel/
• http://www.hexacorn.com/blog/2019/03/30/sqirrel-packages-manager-as-a-lolbin-a-k-a-many-electron-apps-are-lolbins-by-default/
• http://www.hexacorn.com/blog/2018/08/16/squirrel-as-a-lolbin/

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_squirrel_proxy_execution.yml