T1037.002 Login Hook

> Sub-technique of: T1037

High-Level Description

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 <code>/Library/Preferences/com.apple.loginwindow.plist</code> file and can be modified using the <code>defaults</code> 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.

Adversaries can add or insert a path to a malicious script in the <code>com.apple.loginwindow.plist</code> file, using the <code>LoginHook</code> or <code>LogoutHook</code> 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.

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

Kill Chain Phase

• Persistence (TA0003)
• Privilege Escalation (TA0004)

Platforms: macOS

What to Check

• ] Identify if Login Hook technique is applicable to target environment
• ] Check macOS systems for indicators of Login Hook
• ] Verify mitigations are bypassed or absent (1 known mitigations)
• ] Assess detection coverage (1 detection strategies)

How to Test

Atomic Red Team Tests

The following tests are from Atomic Red Team and provide actionable ways to test this technique:

Atomic Test 1: Logon Scripts - Mac

Mac logon script

Supported Platforms: macos

Manual Testing

If Atomic Red Team tests are not applicable, manually verify the technique by:

1. Identify Attack Surface: Determine if the target environment is susceptible to Login Hook by examining the target platforms (macOS).

1. Assess Existing Defenses: Review whether mitigations for T1037.002 are in place. If defenses are absent or misconfigured, this technique may be exploitable.

1. Execute Test: Use tools and methods described in the MITRE ATT&CK page and external references below.

Remediation Guide

M1022 Restrict File and Directory Permissions

Restrict write access to logon scripts to specific administrators.

Detection

Detection Strategy for Login Hook Persistence on macOS

Risk Assessment

| Finding | Severity | Impact | | ------------------------------- | -------- | ----------- | | Login Hook technique applicable | High | Persistence |

CWE Categories

| CWE ID | Title | | ------- | ----------------------------- | | CWE-276 | Incorrect Default Permissions |

References

• Login Scripts Apple Dev
• LoginWindowScripts Apple Dev
• Wardle Persistence Chapter
• S1 macOs Persistence
• Atomic Red Team - T1037.002
• MITRE ATT&CK - T1037.002