Mavinject
Mavinject [T1218.013]
Information
Introduction
Mavinject (T1218.013) is a sub-technique within the MITRE ATT&CK framework categorized under the parent technique "Signed Binary Proxy Execution (T1218)." This sub-technique specifically involves the abuse of the legitimate Windows binary mavinject.exe, a tool originally created by Microsoft to inject accessibility DLLs into running processes. Adversaries exploit this capability to execute malicious code, bypass security controls, and maintain persistence while appearing legitimate to detection tools.
Deep Dive Into Technique
The mavinject.exe binary is a legitimate Windows executable residing typically at the path:
%windir%\System32\mavinject.exe%windir%\SysWOW64\mavinject.exe(on 64-bit systems)
Originally, Microsoft designed this executable to inject accessibility-related DLLs into running applications, assisting users with disabilities. However, adversaries discovered that this legitimate binary can be leveraged for malicious DLL injection attacks. The binary supports command-line arguments allowing attackers to specify the target process and DLL file to inject.
Typical command-line usage for malicious injection could look like this:
Technical details include:
Adversaries must identify a running process (by PID) to inject malicious DLLs into.
The injected DLL typically contains malicious payloads, such as Cobalt Strike beacon, remote access trojans (RATs), or other malware.
Using a legitimate signed binary (
mavinject.exe) allows attackers to bypass application control solutions, such as AppLocker or Windows Defender Application Control (WDAC).The injected DLL executes within the context of the targeted process, inheriting its privileges and permissions, potentially allowing privilege escalation or lateral movement.
When this Technique is Usually Used
Attackers commonly utilize Mavinject in multiple attack scenarios and stages, including:
Initial Access and Execution: Attackers may use this technique shortly after gaining initial access to execute malicious payloads stealthily.
Defense Evasion: Mavinject is often used to bypass application whitelisting and antivirus solutions, as the binary itself is signed by Microsoft and considered trustworthy.
Privilege Escalation: Injecting into a privileged process can grant attackers higher privileges.
Persistence: Attackers can inject malicious DLLs into long-running processes to maintain persistent access.
Lateral Movement: Attackers may inject malicious DLLs into processes running on remote systems after gaining initial foothold in a network.
Typical scenarios include:
Advanced Persistent Threat (APT) groups performing targeted attacks.
Cybercriminal groups deploying ransomware or banking trojans.
Red team engagements simulating realistic adversarial behavior.
How this Technique is Usually Detected
Detection methods for Mavinject abuse include:
Process Monitoring and Command-line Logging: Monitor for executions of
mavinject.exewith unusual command-line arguments, especially referencing uncommon or suspicious DLL paths.Endpoint Detection and Response (EDR) Tools: EDR solutions can detect abnormal DLL injections, especially into sensitive or critical system processes.
Behavioral Analysis: Identify unusual behavior patterns, such as injections into processes that typically do not load external DLLs or injections from uncommon parent processes.
File Integrity Monitoring: Monitor DLL files created or modified in suspicious locations, especially temporary directories, user directories, or unusual file paths.
Sysmon Logging: Configure Sysmon (System Monitor) to detect process creations and DLL loading events involving
mavinject.exe.Indicators of Compromise (IoCs):
Unusual DLL files appearing in
%TEMP%,%APPDATA%, or other user-writable directories.Suspicious DLL file hashes detected by threat intelligence feeds.
Registry changes or persistence mechanisms linked to injected DLLs.
Suspicious parent-child process relationships involving
mavinject.exe.
Why it is Important to Detect This Technique
Early detection of Mavinject abuse is critical due to the following potential impacts:
Stealthy Execution of Malware: Attackers leverage legitimate binaries, making malicious activities harder to identify.
Bypassing Security Controls: Application whitelisting and antivirus software may fail to detect malicious payloads executed via legitimate signed binaries.
Privilege Escalation and System Compromise: Injecting malicious code into privileged processes can lead to privilege escalation, unauthorized system control, and further exploitation.
Persistence and Long-term Compromise: Injected DLLs in long-running processes allow adversaries persistent access, enabling prolonged espionage, data exfiltration, or ransomware deployment.
Lateral Movement and Network-wide Impact: Once attackers establish a foothold, they can leverage Mavinject to move laterally, compromising additional systems and escalating the breach impact.
Early detection allows security teams to:
Quickly identify and respond to intrusions, limiting damage.
Understand adversarial Tactics, Techniques, and Procedures (TTPs) for proactive defense.
Prevent further lateral movement, data exfiltration, or destructive attacks.
Examples
Real-world examples of Mavinject abuse include:
FIN7 Cybercrime Group:
FIN7, known for targeting financial institutions and retail sectors, has leveraged Mavinject to inject malicious payloads into legitimate processes, bypassing security solutions.
Attack Scenario:
Initial phishing email delivers malicious payload.
Payload downloads DLL and uses
mavinject.exeto inject DLL into legitimate Windows processes.Injected DLL establishes command-and-control (C2) channel, enabling data exfiltration and further exploitation.
Impact:
Data breaches, financial losses, and compromised customer data.
APT29 (Cozy Bear):
APT29, associated with espionage activities, has utilized Mavinject to evade detection and maintain persistence.
Attack Scenario:
After initial compromise, attackers inject malicious DLLs into trusted processes using
mavinject.exe.DLL establishes stealthy communication channels to exfiltrate sensitive information.
Impact:
Long-term espionage operations, sensitive data exfiltration, and persistent compromise.
Red Team Engagements:
Security teams and penetration testers frequently simulate adversarial behaviors, including Mavinject DLL injections, to test organizational defenses.
Tools Used:
Cobalt Strike, Metasploit, custom DLL payloads.
Attack Scenario:
Red teams inject DLL payloads into running processes to evade endpoint security controls.
Evaluate organization's detection and response capabilities.
Impact:
Identification of defensive gaps, improved detection strategies, and strengthened security posture.
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