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Detection rules › Sigma

NET NGenAssemblyUsageLog Registry Key Tamper

Status
test
Severity
high
Log source
product windows, category registry_set
Author
frack113
Source
github.com/SigmaHQ/sigma

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.

MITRE ATT&CK coverage

TacticTechniques
PersistenceT1112 Modify Registry
Defense ImpairmentT1112 Modify Registry

Event coverage

ProviderEventTitle
SysmonEvent ID 13RegistryEvent (Value Set)

Rule body yaml

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

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    TargetObject|endswith: 'SOFTWARE\Microsoft\.NETFramework\NGenAssemblyUsageLog'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
TargetObjectends_with
  • SOFTWARE\Microsoft\.NETFramework\NGenAssemblyUsageLog