T1037.002 Logon Script (Mac)

Adversaries may use macOS logon scripts automatically executed at logon initialization to establish persistence. macOS allows logon scripts (known as login hooks) to be executed whenever a specific user logs into a system. A login hook tells Mac OS X to execute a certain script when a user logs in, but unlike Startup Items, a login hook executes as the elevated root user.(Citation: creating login hook)

Adversaries may use these login hooks to maintain persistence on a single system.(Citation: S1 macOs Persistence) Access to login hook scripts may allow an adversary to insert additional malicious code. There can only be one login hook at a time though and depending on the access configuration of the hooks, either local credentials or an administrator account may be necessary.