Attempt to Remove File Quarantine Attribute

Elastic Stack Serverless Security

Identifies a potential Gatekeeper bypass. In macOS, when applications or programs are downloaded from the internet, there is a quarantine flag set on the file. This attribute is read by Apple’s Gatekeeper defense program at execution time. An adversary may disable this attribute to evade defenses.

Rule type: eql

Rule indices:

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

Severity: medium

Risk score: 47

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://www.trendmicro.com/en_us/research/20/k/new-macos-backdoor-connected-to-oceanlotus-surfaces.html
• https://ss64.com/osx/xattr.html

Tags:

• Elastic
• Host
• macOS
• Threat Detection
• Defense Evasion

Version: 101

Rule authors:

• Elastic

Rule license: Elastic License v2

process where event.type in ("start", "process_started") and
  process.name : "xattr" and
  (
    (process.args : "com.apple.quarantine" and process.args : ("-d", "-w")) or
    (process.args : "-c") or
    (process.command_line : ("/bin/bash -c xattr -c *", "/bin/zsh -c xattr -c *", "/bin/sh -c xattr -c *"))
  ) and not process.args_count > 12

Framework: MITRE ATT&CKTM

• Tactic:

  • Name: Defense Evasion
  • ID: TA0005
  • Reference URL: https://attack.mitre.org/tactics/TA0005/

• Technique:

  • Name: Impair Defenses
  • ID: T1562
  • Reference URL: https://attack.mitre.org/techniques/T1562/

• Sub-technique:

  • Name: Disable or Modify Tools
  • ID: T1562.001
  • Reference URL: https://attack.mitre.org/techniques/T1562/001/