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T1037.002 - Login Hook

T1037.002 - Login Hook#

Adversaries may use a Login Hook to establish persistence executed upon user logon. A login hook is a plist file that points to a specific script to execute with root privileges upon user logon. The plist file is located in the /Library/Preferences/com.apple.loginwindow.plist file and can be modified using the defaults command-line utility. This behavior is the same for logout hooks where a script can be executed upon user logout. All hooks require administrator permissions to modify or create hooks.(Citation: Login Scripts Apple Dev)(Citation: LoginWindowScripts Apple Dev)

Adversaries can add or insert a path to a malicious script in the com.apple.loginwindow.plist file, using the LoginHook or LogoutHook key-value pair. The malicious script is executed upon the next user login. If a login hook already exists, adversaries can add additional commands to an existing login hook. There can be only one login and logout hook on a system at a time.(Citation: S1 macOs Persistence)(Citation: Wardle Persistence Chapter)

Note: Login hooks were deprecated in 10.11 version of macOS in favor of Launch Daemon and Launch Agent

Atomic Tests#

Atomic Test #1 - Logon Scripts - MacMac logon script#

Supported Platforms: macosRun it with these steps!1. Create the required plist file

sudo touch /private/var/root/Library/Preferences/com.apple.loginwindow.plist

  1. Populate the plist with the location of your shell script

    sudo defaults write com.apple.loginwindow LoginHook /Library/Scripts/AtomicRedTeam.sh

  2. Create the required plist file in the target user’s Preferences directory

    touch /Users/$USER/Library/Preferences/com.apple.loginwindow.plist

  3. Populate the plist with the location of your shell script

    defaults write com.apple.loginwindow LoginHook /Library/Scripts/AtomicRedTeam.sh

Detection#

Monitor logon scripts for unusual access by abnormal users or at abnormal times. Look for files added or modified by unusual accounts outside of normal administration duties. Monitor running process for actions that could be indicative of abnormal programs or executables running upon logon.

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