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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:

Tags:

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

Version: 4

Rule authors:

  • Elastic

Rule license: Elastic License v2

Investigation guide

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

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&CKTM