Linux Persistence via Crontab Modification or Suspicious Cron Job

SIGMA detection rule by Damir Sadikov · Unknown

Detects creation or modification of cron-related files and the registration of cron jobs that execute from world-writable or temporary directories, or that pipe remote content to a shell. Cron is one of the most common Linux persistence mechanisms.

title: Linux Persistence via Crontab Modification or Suspicious Cron Job
id: 3a6d9f28-7c14-4e62-b9a8-5d2f8c1b7043
status: experimental
description: |
  Detects creation or modification of cron-related files and the registration
  of cron jobs that execute from world-writable or temporary directories, or
  that pipe remote content to a shell. Cron is one of the most common Linux
  persistence mechanisms.
references:
  - https://attack.mitre.org/techniques/T1053/003/
author: Damir Sadikov
date: 2026/05/28
tags:
  - attack.persistence
  - attack.t1053.003
logsource:
  product: linux
  service: cron
detection:
  selection_path:
    CommandLine|contains:
      - '/tmp/'
      - '/dev/shm/'
      - '/var/tmp/'
  selection_remote:
    CommandLine|contains|all:
      - 'curl'
      - 'sh'
  selection_remote_alt:
    CommandLine|contains|all:
      - 'wget'
      - 'bash'
  condition: selection_path or selection_remote or selection_remote_alt
fields:
  - User
  - CommandLine
falsepositives:
  - Legitimate maintenance jobs that use temporary working directories.
level: medium

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

44d2ff27-158d-4de8-8c63-1bf82b861173

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Executable code, not a declarative rule

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