Detection rules › Sigma

Audit policy disabled by command line

Status
experimental
Severity
high
Log source
product windows, service security
Author
mdecrevoisier
Source
github.com/mdecrevoisier/SIGMA-detection-rules

Detects scenarios where an attacker attempts disbaled the audit policy for defense evasion purposes.

MITRE ATT&CK coverage

Event coverage

Rule body yaml

title: Audit policy disabled by command line
description: Detects scenarios where an attacker attempts disbaled the audit policy for defense evasion purposes.
references:
- https://github.com/mdecrevoisier/EVTX-to-MITRE-Attack/tree/master/TA0005-Defense%20Evasion/T1562.002-Disable%20Windows%20Event%20Logging
- https://searchitchannel.techtarget.com/feature/Using-AuditPol-to-audit-Windows-users-and-set-policies
tags:
- attack.defense_evasion
- attack.t1562.002
author: mdecrevoisier
status: experimental
logsource:
  product: windows
  service: security
detection:
  selection:
    EventID: 4719 # System audit policy was changed.
    AuditPolicyChanges|contains:
      - '%%8448' # Success removed
      - '%%8450' # Failure removed
  filter:
    SubjectUserName|endswith: $ # Excludes system or GPO changes
  condition: selection and not filter
falsepositives:
- Administrator debugging audit policy
level: high

Stages and Predicates

Stage 0: condition

selection and not filter

Stage 1: selection

selection:
  EventID: 4719
  AuditPolicyChanges|contains:
    - '%%8448'
    - '%%8450'

Stage 2: not filter

filter:
  SubjectUserName|endswith: $

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

FieldKindExcluded values
SubjectUserNameends_with$

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
AuditPolicyChangesmatch
  • %%8448 corpus 3 (sigma 3)
  • %%8450 corpus 3 (sigma 3)