Suspicious Calendar File Modification

edit

Identifies suspicious modifications of the calendar file by an unusual process. Adversaries may create a custom calendar notification procedure to execute a malicious program at a recurring interval to establish persistence.

Rule type: query

Rule indices:

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

Severity: medium

Risk score: 47

Runs every: 5 minutes

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
  • Persistence

Version: 1

Added (Elastic Stack release): 7.12.0

Rule authors: Elastic

Rule license: Elastic License v2

Potential false positives

edit

Trusted applications for managing calendars and reminders.

Rule query

edit
event.category:file and event.action:modification and
file.path:/Users/*/Library/Calendars/*.calendar/Events/*.ics and
process.executable: (* and not ( /System/Library/* or
/System/Applications/Calendar.app/Contents/MacOS/* or
/usr/libexec/xpcproxy or /sbin/launchd or
/Applications/* ) )

Threat mapping

edit

Framework: MITRE ATT&CKTM