Login Hook
Login Hook [T1037.002]
Information
Name: Login Hook
ID: T1037.002
Technique: T1037
Introduction
Login Hook (T1037.002) is a sub-technique from the MITRE ATT&CK framework under the Persistence tactic and Boot or Logon Autostart Execution technique. Attackers leverage login hooks to execute malicious code automatically upon user login, ensuring persistence on compromised macOS systems. This technique exploits built-in macOS functionality designed to run scripts or executables when a user logs in, enabling attackers to maintain access and execute further commands or payloads seamlessly without user awareness.
Deep Dive Into Technique
Login hooks are scripts or executables configured to run automatically at user login on macOS systems. Historically, macOS provided built-in support for login hooks through the command-line utility:
Technical details and execution methods include:
Login Hooks Configuration: Attackers create or modify login hook scripts, typically shell scripts, that execute malicious commands or payloads upon user login.
Privilege Requirements: Login hooks require administrative privileges to set or modify. Attackers usually escalate privileges or use compromised admin credentials.
Persistence Mechanism: Once configured, login hooks run automatically each time a user logs in, providing long-term persistence.
Script Locations and Formats:
Commonly stored in hidden or obscure directories (
/Library/,/usr/local/bin/,/Users/Shared/).Usually shell scripts (
.sh) or executable binaries.
Obfuscation and Evasion:
Attackers may obfuscate scripts or store them in hidden directories.
Scripts may reference external payloads or command-and-control servers.
Real-world Procedures:
Attackers may combine login hooks with other persistence mechanisms (launch agents, daemons).
Login hooks may download additional malware, establish remote access, or collect user/system information.
When this Technique is Usually Used
Attackers typically leverage login hooks in various attack scenarios and stages, including:
Persistence Stage:
Maintaining long-term access after initial compromise.
Surviving system reboots or user logouts.
Post-Exploitation Stage:
Ensuring continued command-and-control (C2) communication.
Re-establishing backdoors after detection or partial remediation.
Privilege Escalation Scenarios:
After gaining administrative credentials, attackers configure login hooks to automate privilege escalation payloads or maintain elevated access.
Targeted Attacks:
Advanced Persistent Threats (APTs) targeting macOS environments commonly use login hooks for persistence.
Espionage campaigns where stealthy persistence mechanisms are crucial.
How this Technique is Usually Detected
Detection methods, tools, and indicators of compromise (IoCs) include:
System Configuration Audits:
Regularly auditing macOS login hook configurations through commands such as:
File Integrity Monitoring (FIM):
Monitoring unexpected changes or additions to scripts or executables in common system directories (
/Library/,/usr/local/bin/,/Users/Shared/).
Endpoint Detection and Response (EDR):
EDR solutions may detect suspicious file creations, modifications, or executions triggered by login hooks.
Behavioral Monitoring:
Detecting anomalous processes or scripts running immediately after user login.
Monitoring network connections initiated by processes spawned from login hooks.
Log Analysis:
Reviewing macOS system logs (
/var/log/system.log) for unusual login hook activity or errors.
Specific Indicators of Compromise (IoCs):
Presence of unauthorized login hook scripts or binaries.
Suspicious network traffic initiated by login hook scripts.
Unexpected persistence mechanisms detected in macOS configuration.
Why it is Important to Detect This Technique
Early detection of login hook persistence is critical due to potential severe impacts on systems and networks:
Long-Term Persistence:
Attackers maintain persistent, stealthy access, allowing ongoing espionage, data exfiltration, or lateral movement.
Stealthy Execution:
Login hooks execute automatically and silently, making detection difficult without proactive monitoring.
System Integrity and Security:
Undetected login hooks can compromise system integrity, enabling attackers to escalate privileges, install additional malware, or exfiltrate sensitive data.
Data Exfiltration and Espionage:
Attackers may leverage login hooks to establish persistent command-and-control channels, facilitating data theft or espionage.
Operational Disruption:
Persistent threats can disrupt business operations, degrade system performance, or lead to compliance violations.
Early Mitigation:
Timely detection allows security teams to remediate threats before significant damage occurs, minimizing impact and recovery costs.
Examples
Real-world examples demonstrating the use of login hooks include:
FruitFly Malware:
A macOS malware family that utilized login hooks to maintain persistent access.
Attackers configured login hooks to execute malicious scripts upon user login, enabling remote access, surveillance capabilities, and data exfiltration.
FruitFly targeted healthcare, biomedical research facilities, and individual users, highlighting the stealth and effectiveness of login hook persistence.
OSX.Dok Malware:
Leveraged login hooks to establish persistent backdoors on compromised macOS systems.
Upon infection, OSX.Dok installed malicious scripts as login hooks, enabling attackers to intercept internet traffic, steal credentials, and install additional malware.
Demonstrated sophisticated persistence coupled with credential harvesting and man-in-the-middle attacks.
Advanced Persistent Threat (APT) Campaigns:
Nation-state threat actors have utilized login hooks in targeted espionage campaigns against macOS users.
Attackers employed login hooks to silently execute reconnaissance scripts, exfiltrate sensitive data, and maintain long-term undetected access to victim networks.
In these examples, attackers leveraged login hooks due to their stealth, persistence, and ease of deployment, underscoring the importance of proactive detection and mitigation strategies.
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