Registry-Free Process Scope COR_PROFILER

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)

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Detection logic

selection

ScriptBlockText|contains|all:
  - $env:COR_ENABLE_PROFILING
  - $env:COR_PROFILER
  - $env:COR_PROFILER_PATH

Condition

selection

Raw YAML

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