Potentially Suspicious Child Process Of VsCode — Sigma Rule

Rule metadata and linked tags

Author: Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: medium. Source dates: 2023-01-26 / 2023-10-25.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 8ba9daa27e398f5b7a7c917c57060dc2692d8c94d78f23d9c3d9fa311b99ea81

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Potentially Suspicious Child Process Of VsCode
id: 5a3164f2-b373-4152-93cf-090b13c12d27
status: test
description: Detects uncommon or suspicious child processes spawning from a VsCode "code.exe" process. This could indicate an attempt of persistence via VsCode tasks or terminal profiles.
references:
    - https://twitter.com/nas_bench/status/1618021838407495681
    - https://twitter.com/nas_bench/status/1618021415852335105
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-01-26
modified: 2023-10-25
tags:
    - attack.execution
    - attack.stealth
    - attack.t1218
    - attack.t1202
logsource:
    category: process_creation
    product: windows
detection:
    selection_parent:
        ParentImage|endswith: '\code.exe'
    selection_children_images:
        Image|endswith:
            - '\calc.exe'
            - '\regsvr32.exe'
            - '\rundll32.exe'
            - '\cscript.exe'
            - '\wscript.exe'
    selection_children_cli:
        Image|endswith:
            - '\powershell.exe'
            - '\pwsh.exe'
            - '\cmd.exe'
        CommandLine|contains:
            - 'Invoke-Expressions'
            - 'IEX'
            - 'Invoke-Command'
            - 'ICM'
            - 'DownloadString'
            - 'rundll32'
            - 'regsvr32'
            - 'wscript'
            - 'cscript'
    selection_children_paths:
        Image|contains:
            # Add more suspicious locations
            - ':\Users\Public\'
            - ':\Windows\Temp\'
            - ':\Temp\'
    condition: selection_parent and 1 of selection_children_*
falsepositives:
    - In development environment where VsCode is used heavily. False positives may occur when developers use task to compile or execute different types of code. Remove or add processes accordingly
level: medium

Original YAML and metadata in JSON

False positives

• In development environment where VsCode is used heavily. False positives may occur when developers use task to compile or execute different types of code. Remove or add processes accordingly

Source references

• https://twitter.com/nas_bench/status/1618021838407495681
• https://twitter.com/nas_bench/status/1618021415852335105