Scheduled Cron Task/Job - Linux — Sigma Rule

Rule metadata and linked tags

Author: Alejandro Ortuno, oscd.community. Source status: test; severity: medium. Source dates: 2020-10-06 / 2022-11-27.

{
  "category": "process_creation",
  "product": "linux"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: f5e630f32a2d9793bde25c9a00370a593e622a7ef639b4ea0e282a5befea26a2

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: Scheduled Cron Task/Job - Linux
id: 6b14bac8-3e3a-4324-8109-42f0546a347f
status: test
description: Detects abuse of the cron utility to perform task scheduling for initial or recurring execution of malicious code. Detection will focus on crontab jobs uploaded from the tmp folder.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1053.003/T1053.003.md
author: Alejandro Ortuno, oscd.community
date: 2020-10-06
modified: 2022-11-27
tags:
    - attack.execution
    - attack.persistence
    - attack.privilege-escalation
    - attack.t1053.003
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        Image|endswith: 'crontab'
        CommandLine|contains: '/tmp/'
    condition: selection
falsepositives:
    - Legitimate administration activities
level: medium

Original YAML and metadata in JSON

False positives

• Legitimate administration activities

Source references

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