Attempt to Remove File Quarantine Attribute

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 (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

Elastic
Host
macOS
Threat Detection
Defense Evasion

Version: 4

Rule authors:

Elastic

Rule license: Elastic License v2

Investigation guide

edit

## Config

If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define `event.ingested` and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate `event.ingested` to @timestamp for this rule to work.

Rule query

edit

process where event.type in ("start", "process_started") and
  process.args : "xattr" and
  (
    (process.args : "com.apple.quarantine" and process.args : ("-d", "-w")) or
    (process.args : "-c" and process.command_line :
      (
        "/bin/bash -c xattr -c *",
        "/bin/zsh -c xattr -c *",
        "/bin/sh -c xattr -c *"
      )
    )
  )

Framework: MITRE ATT&CK^TM

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/

« SystemKey Access via Command Line Potential Privacy Control Bypass via TCCDB Modification »