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Elastic Docs ›Elastic Security Solution [8.4] ›Detections and alerts ›Prebuilt rule reference

Suspicious Calendar File Modification

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Suspicious Calendar File Modification

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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: 3 (version history)

Added (Elastic Stack release): 7.12.0

Last modified (Elastic Stack release): 8.4.0

Rule authors: Elastic

Rule license: Elastic License v2

Potential false positives

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Trusted applications for managing calendars and reminders.

Rule query

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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
/System/Applications/Mail.app/Contents/MacOS/Mail or
/usr/libexec/xpcproxy or /sbin/launchd or /Applications/*
) )

Threat mapping

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Framework: MITRE ATT&CKTM

Rule version history

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Version 3 (8.4.0 release)

  • Updated query, changed from:

    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/* ) )
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