Apple MacOS, Login Hook Persistence: Techniques, Prevention, and Detection

ReZa AdineH
2 min readMar 19, 2023

Abstract:

Adversaries can use Login Hooks as a technique to establish persistence and execute malicious code upon user logon on macOS. This white paper explores the mechanism behind Login Hooks, the techniques adversaries use to exploit them, and preventive measures that organizations can implement to protect their systems. The paper also discusses detection methods and provides guidance on how to detect and respond to this type of attack.

Introduction:

Login Hooks are a mechanism provided by macOS to execute a script with root privileges upon user login. Adversaries can abuse this feature to establish persistence and execute malicious code that can evade detection. This white paper describes how adversaries use Login Hooks, how organizations can prevent this type of attack, and how to detect and respond to it.

Techniques:

Adversaries can use several techniques to exploit Login Hooks, including modifying the /Library/Preferences/com.apple.loginwindow.plist file to point to a malicious script. They can also use a tool like defaults to modify or create new Login Hooks. Once the script is executed upon login, it can perform various actions, such as downloading and executing additional malware, stealing data, or creating a backdoor. Adversaries can also use similar techniques to create Logout Hooks, which execute a script upon user logout.

Prevention:

To prevent Login Hook attacks, organizations can implement the following measures:

  1. Restrict access to the /Library/Preferences/com.apple.loginwindow.plist file to authorized personnel.
  2. Monitor changes to the Login Hooks list and validate that each script is legitimate.
  3. Implement endpoint protection software that can detect and prevent malicious scripts from executing.
  4. Train users to recognize phishing attempts and avoid clicking on suspicious links or downloading files from untrusted sources.

Detection:

Organizations can detect Login Hook attacks by monitoring changes to the /Library/Preferences/com.apple.loginwindow.plist file and verifying that each script is legitimate. They can also use endpoint detection and response (EDR) software that can detect the execution of malicious scripts and provide alerts to security teams.

Additionally, organizations can leverage logging and monitoring tools to detect unusual activity, such as unexpected network connections or processes running with elevated privileges. Regular vulnerability scans and penetration tests can also help identify and address security weaknesses that adversaries can exploit.

Conclusion:

Login Hook Persistence is a technique that adversaries can use to establish persistence and execute malicious code upon user logon. This white paper provides an overview of the technique, the techniques adversaries use to exploit it, and preventive measures that organizations can implement to protect their systems. By implementing these measures and using detection and response tools, organizations can mitigate the risk of Login Hook attacks and improve their overall security posture.

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ReZa AdineH

Hey, this is Reza Adineh, SOC Architect and consultant, SIEM Engineer, Threat Detection Engineer. follow me on RezaAdineh.info