Registry-Free Process Scope COR_PROFILER — Sigma Rule

Rule metadata and linked tags

Author: frack113. Source status: test; severity: medium. Source dates: 2021-12-30 / not supplied.

{
  "product": "windows",
  "category": "ps_script",
  "definition": "Requirements: Script Block Logging must be enabled"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 37f7d327cf6f5d9ae05bf5421e6b0c8908f56364a6a166e6e6a709b9a77d2a2f

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: Registry-Free Process Scope COR_PROFILER
id: 23590215-4702-4a70-8805-8dc9e58314a2
status: test
description: |
    Adversaries may leverage the COR_PROFILER environment variable to hijack the execution flow of programs that load the .NET CLR.
    The COR_PROFILER is a .NET Framework feature which allows developers to specify an unmanaged (or external of .NET) profiling DLL to be loaded into each .NET process that loads the Common Language Runtime (CLR).
    These profiliers are designed to monitor, troubleshoot, and debug managed code executed by the .NET CLR.
    (Citation: Microsoft Profiling Mar 2017)
    (Citation: Microsoft COR_PROFILER Feb 2013)
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1574.012/T1574.012.md#atomic-test-3---registry-free-process-scope-cor_profiler
author: frack113
date: 2021-12-30
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.execution
    - attack.stealth
    - attack.t1574.012
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    selection:
        ScriptBlockText|contains|all:
            - '$env:COR_ENABLE_PROFILING'
            - '$env:COR_PROFILER'
            - '$env:COR_PROFILER_PATH'
    condition: selection
falsepositives:
    - Legitimate administrative script
level: medium

Original YAML and metadata in JSON

False positives

• Legitimate administrative script

Source references

• https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1574.012/T1574.012.md#atomic-test-3---registry-free-process-scope-cor_profiler