Elastic Security Detection Rules

Suspicious Calendar File Modification

Last updated 5 months ago on 2025-03-18
Created 5 years ago on 2021-01-19

About

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.
Tags
Domain: EndpointOS: macOSUse Case: Threat DetectionTactic: PersistenceData Source: Elastic DefendLanguage: eql
Severity
medium
Risk Score
47
MITRE ATT&CK™

Persistence (TA0003)(opens in a new tab or window)

↳ Event Triggered Execution (T1546)(opens in a new tab or window)

False Positive Examples
Trusted applications for managing calendars and reminders.
License
Elastic License v2(opens in a new tab or window)

Definition

Rule Type
Event Correlation Rule
Integration Pack
Prebuilt Security Detection Rules
Index Patterns
logs-endpoint.events.*
Related Integrations

endpoint(opens in a new tab or window)

Query
file where host.os.type == "macos" and event.action == "modification" and
  file.path like~ "/Users/*/Library/Calendars/*.calendar/Events/*.ics" and
  not process.executable like ("/System/Library/*", "/System/Applications/Calendar.app/Contents/MacOS/*", 
                               "/System/Applications/Mail.app/Contents/MacOS/Mail", "/usr/libexec/xpcproxy",
                               "/sbin/launchd", "/Applications/*")

Install detection rules in Elastic Security

Detect Suspicious Calendar File Modification in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(opens in a new tab or window).