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Launch Agent

Per Apple’s developer documentation, when a user logs in, a per-user launchd process is started which loads the parameters for each launch-on-demand user agent from the property list (plist) files found in /System/Library/LaunchAgents, /Library/LaunchAgents, and $HOME/Library/LaunchAgents [1] [2] [3]. These launch agents have property list files which point to the executables that will be launched [4].

Adversaries may install a new launch agent that can be configured to execute at login by using launchd or launchctl to load a plist into the appropriate directories [5] [6]. The agent name may be disguised by using a name from a related operating system or benign software. Launch Agents are created with user level privileges and are executed with the privileges of the user when they log in [7] [8]. They can be set up to execute when a specific user logs in (in the specific user’s directory structure) or when any user logs in (which requires administrator privileges).

ID: T1159

Tactic: Persistence

Platform:  macOS

Permissions Required:  User, Administrator

Data Sources:  File monitoring, Process monitoring

Version: 1.0

Examples

NameDescription
Calisto

Calisto adds a .plist file to the /Library/LaunchAgents folder to maintain persistence.[9]

CrossRAT

CrossRAT creates a Launch Agent on macOS.

Dok

Dok persists via a Launch Agent.[10]

FruitFly

FruitFly persists via a Launch Agent.[10]

Keydnap

Keydnap uses a Launch Agent to persist.[11]

Komplex

The Komplex trojan creates a persistent launch agent called with $HOME/Library/LaunchAgents/com.apple.updates.plist with launchctl load -w ~/Library/LaunchAgents/com.apple.updates.plist.[5]

MacSpy

MacSpy persists via a Launch Agent.[10]

Proton

Proton persists via a Launch Agent.[10]

Mitigation

Restrict user's abilities to create Launch Agents with group policy.

Detection

Monitor Launch Agent creation through additional plist files and utilities such as Objective-See’s KnockKnock application. Launch Agents also require files on disk for persistence which can also be monitored via other file monitoring applications.

References