NET NGenAssemblyUsageLog Registry Key Tamper — Sigma Rule

Rule metadata and linked tags

Author: frack113. Source status: test; severity: high. Source dates: 2022-11-18 / 2023-08-17.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: cfe8c11907ec3faaa782e136a299d200611fb8ab5a86a3642650ae1e42276d26

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: NET NGenAssemblyUsageLog Registry Key Tamper
id: 28036918-04d3-423d-91c0-55ecf99fb892
status: test
description: |
  Detects changes to the NGenAssemblyUsageLog registry key.
  .NET Usage Log output location can be controlled by setting the NGenAssemblyUsageLog CLR configuration knob in the Registry or by configuring an environment variable (as described in the next section).
  By simplify specifying an arbitrary value (e.g. fake output location or junk data) for the expected value, a Usage Log file for the .NET execution context will not be created.
references:
    - https://bohops.com/2021/03/16/investigating-net-clr-usage-log-tampering-techniques-for-edr-evasion/
author: frack113
date: 2022-11-18
modified: 2023-08-17
tags:
    - attack.persistence
    - attack.defense-impairment
    - attack.t1112
logsource:
    product: windows
    category: registry_set
detection:
    selection:
        TargetObject|endswith: 'SOFTWARE\Microsoft\.NETFramework\NGenAssemblyUsageLog'
    condition: selection
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://bohops.com/2021/03/16/investigating-net-clr-usage-log-tampering-techniques-for-edr-evasion/