Modifying Crontab — Sigma Rule

Rule metadata and linked tags

Author: Pawel Mazur. Source status: test; severity: medium. Source dates: 2022-04-16 / not supplied.

{
  "product": "linux",
  "service": "cron"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 57fae599a26cc85cc62453bdbff9c226cbffc940bf4e66dc2933244abe937f3e

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: Modifying Crontab
id: af202fd3-7bff-4212-a25a-fb34606cfcbe
status: test
description: Detects suspicious modification of crontab file.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1053.003/T1053.003.md
author: Pawel Mazur
date: 2022-04-16
tags:
    - attack.privilege-escalation
    - attack.execution
    - attack.persistence
    - attack.t1053.003
logsource:
    product: linux
    service: cron
detection:
    keywords:
        - 'REPLACE'
    condition: keywords
falsepositives:
    - Legitimate modification of crontab
level: medium

Original YAML and metadata in JSON

False positives

• Legitimate modification of crontab

Source references

• https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1053.003/T1053.003.md