Detection rules › Sigma

macOS Authentication Events

Status
experimental
Severity
low
Log source
product macos, service unifiedlog
Author
Eric Brown - Nebulock, Inc.
Source
github.com/Nebulock-Inc/macos-coresigma

Detects authentication-related events from the macOS authorization subsystem. Monitors for login attempts, credential validation, and authorization requests which may indicate initial access attempts or compromised credentials.

MITRE ATT&CK coverage

TacticTechniques
Initial AccessT1078 Valid Accounts
Credential AccessT1555 Credentials from Password Stores

Rule body yaml

title: macOS Authentication Events
id: 3697a253-44ea-4276-b805-f07935c82538
status: experimental
description: 'Detects authentication-related events from the macOS authorization subsystem.

  Monitors for login attempts, credential validation, and authorization requests

  which may indicate initial access attempts or compromised credentials.

  '
author: Eric Brown - Nebulock, Inc.
date: 2025/10/31
modified: 2025/10/31
references:
- https://attack.mitre.org/techniques/T1078/
- https://developer.apple.com/documentation/os/logging
logsource:
  product: macos
  service: unifiedlog
detection:
  selection_subsystem:
    subsystem: com.apple.authorization
  selection_keywords:
    message|contains:
    - authentication
    - login
    - credential
    - authorize
  condition: selection_subsystem and selection_keywords
falsepositives:
- Normal user authentication and login activity
- System services performing authorized operations
- Legitimate administrative tasks
fields:
- subsystem
- category
- process
- message
- level
tags:
- attack.initial_access
- attack.t1078
- attack.credential_access
- attack.t1555
level: low

Stages and Predicates

Stage 0: condition

selection_subsystem and selection_keywords

Stage 1: selection_subsystem

selection_subsystem:
  subsystem: com.apple.authorization

Stage 2: selection_keywords

selection_keywords:
  message|contains:
  - authentication
  - login
  - credential
  - authorize

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
messagematch
  • authentication
  • authorize
  • credential
  • login
subsystemeq
  • com.apple.authorization