Potential Microsoft Office Sandbox Evasion

Elastic Stack Serverless Security

Identifies the creation of a suspicious zip file prepended with special characters. Sandboxed Microsoft Office applications on macOS are allowed to write files that start with special characters, which can be combined with an AutoStart location to achieve sandbox evasion.

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://i.blackhat.com/USA-20/Wednesday/us-20-Wardle-Office-Drama-On-macOS.pdf
• https://www.mdsec.co.uk/2018/08/escaping-the-sandbox-microsoft-office-on-macos/
• https://desi-jarvis.medium.com/office365-macos-sandbox-escape-fcce4fa4123c

Tags:

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

Version: 101

Rule authors:

• Elastic

Rule license: Elastic License v2

event.category:file and not event.type:deletion and file.name:~$*.zip and host.os.type:macos

Framework: MITRE ATT&CKTM

• Tactic:

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

• Technique:

  • Name: Virtualization/Sandbox Evasion
  • ID: T1497
  • Reference URL: https://attack.mitre.org/techniques/T1497/