Privilege Escalation via Root Crontab File Modification

Elastic Stack Serverless Security

Identifies modifications to the root crontab file. Adversaries may overwrite this file to gain code execution with root privileges by exploiting privileged file write or move related vulnerabilities.

Rule type: query

Rule indices:

• auditbeat-*
• logs-endpoint.events.*

Severity: high

Risk score: 73

Runs every: 5m

Searches indices from: now-9m (https://www.elastic.co/guide/en/elasticsearch/reference/current/common-options.html#date-math[Date Math format], see also Additional look-back time)

Maximum alerts per execution: 100

References:

• https://phoenhex.re/2017-06-09/pwn2own-diskarbitrationd-privesc
• https://www.exploit-db.com/exploits/42146

Tags:

• Elastic
• Host
• macOS
• Threat Detection
• Privilege Escalation

Version: 101

Rule authors:

• Elastic

Rule license: Elastic License v2

event.category:file and not event.type:deletion and
 file.path:/private/var/at/tabs/root and not process.executable:/usr/bin/crontab

Framework: MITRE ATT&CKTM

• Tactic:

  • Name: Privilege Escalation
  • ID: TA0004
  • Reference URL: https://attack.mitre.org/tactics/TA0004/

• Technique:

  • Name: Scheduled Task/Job
  • ID: T1053
  • Reference URL: https://attack.mitre.org/techniques/T1053/

• Sub-technique:

  • Name: Cron
  • ID: T1053.003
  • Reference URL: https://attack.mitre.org/techniques/T1053/003/