Unexpected Child Process of macOS Screensaver Engineedit

Identifies when a child process is spawned by the screensaver engine process, which is consistent with an attacker’s malicious payload being executed after the screensaver activated on the endpoint. An adversary can maintain persistence on a macOS endpoint by creating a malicious screensaver (.saver) file and configuring the screensaver plist file to execute code each time the screensaver is activated.

Rule type: eql

Rule indices:

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

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: 5 (version history)

Added (Elastic Stack release): 7.16.0

Last modified (Elastic Stack release): 8.4.0

Rule authors: Elastic

Rule license: Elastic License v2

Investigation guideedit

## Triage and analysis

- Analyze the descendant processes of the ScreenSaverEngine process for malicious code and suspicious behavior such
as a download of a payload from a server.
- Review the installed and activated screensaver on the host. Triage the screensaver (.saver) file that was triggered to
identify whether the file is malicious or not.

Rule queryedit

process where event.type == "start" and process.parent.name ==
"ScreenSaverEngine"

Threat mappingedit

Framework: MITRE ATT&CKTM

Rule version historyedit

Version 5 (8.4.0 release)
  • Formatting only
Version 3 (8.2.0 release)
  • Formatting only
Version 2 (8.1.0 release)
  • Formatting only