persistence_suspicious_calendar_modification.toml

[metadata]
creation_date = "2021/01/19"
integration = ["endpoint"]
maturity = "production"
min_stack_comments = "New fields added: required_fields, related_integrations, setup"
min_stack_version = "8.3.0"
updated_date = "2023/02/22"

[rule]
author = ["Elastic"]
description = """
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.
"""
false_positives = ["Trusted applications for managing calendars and reminders."]
from = "now-9m"
index = ["logs-endpoint.events.*", "auditbeat-*"]
language = "kuery"
license = "Elastic License v2"
name = "Suspicious Calendar File Modification"
references = [
    "https://labs.f-secure.com/blog/operationalising-calendar-alerts-persistence-on-macos",
    "https://github.com/FSecureLABS/CalendarPersist",
    "https://github.com/D00MFist/PersistentJXA/blob/master/CalendarPersist.js",
]
risk_score = 47
rule_id = "cb71aa62-55c8-42f0-b0dd-afb0bb0b1f51"
severity = "medium"
tags = ["Elastic", "Host", "macOS", "Threat Detection", "Persistence"]
timestamp_override = "event.ingested"
type = "query"

query = '''
event.category:file and host.os.type:macos 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/*
    )
  )
'''


[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
id = "T1546"
name = "Event Triggered Execution"
reference = "https://attack.mitre.org/techniques/T1546/"


[rule.threat.tactic]
id = "TA0003"
name = "Persistence"
reference = "https://attack.mitre.org/tactics/TA0003/"