Unexpected Child Process of macOS Screensaver Engine

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Unexpected Child Process of macOS Screensaver Engine

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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:

  • logs-endpoint.events.*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Domain: Endpoint
  • OS: macOS
  • Use Case: Threat Detection
  • Tactic: Persistence
  • Data Source: Elastic Defend

Version: 106

Rule authors:

  • Elastic

Rule license: Elastic License v2

Investigation guide

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## 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 query

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

Framework: MITRE ATT&CKTM