Persistence mechanisms are the cornerstone of effective red teaming operations, particularly in simulating Advanced Persistent Threats (APTs). These mechanisms enable threat actors to retain unauthorized access and exert control over targeted systems, often evading detection for extended periods. Among the myriad of techniques at the disposal of red teamers, COM Hijacking stands out as an exceptionally stealthy method. This file-less strategy is a game-changer.
When attackers secure a foothold within a system, they gravitate towards maintaining that access with the highest possible privileges. This approach is strategic, as it mitigates the risk of exposure that comes with repeated use of the initial exploit—particularly when said exploit is of a complex nature or is a one-shot vector that cannot be reliably reused.
Key Persistence Techniques Employed by Attackers
- Scheduled Tasks: This involves the creation of tasks programmed to execute malicious activities at predefined times or during system boot-up. By configuring these tasks to operate with elevated system privileges, attackers ensure that they have a persistent backdoor into the system, even after initial security breaches are patched.
- Fileless Persistence: The use of in-memory execution techniques, primarily through PowerShell or Windows Management Instrumentation (WMI), falls under fileless persistence. By avoiding the filesystem, these methods complicate the detection process and pose a significant challenge for security analysts attempting to track and analyze malicious activities.
- Service Installation: Another common approach is to install services that function as covert backdoors. These services may masquerade as legitimate system processes but are, in reality, entry points for attackers to remotely administer the compromised host.
A Closer Look at COM Hijacking
However, the focus of our Blog is COM Hijacking—a nuanced file-less attack. This tactic exploits the Windows Component Object Model (COM), a system integral to enabling inter-component communication. By manipulating registry keys associated with COM objects, an attacker can redirect application execution paths to activate their code without detection.
Executing the Hijack:
- Registry Modification: The first step involves editing the registry key ‘HKEY_LOCAL_MACHINE\SOFTWARE\Classes\mscfile\shell\open\command’ to replace its default value with a PowerShell command.
The default registry value for executing the Microsoft Management Console (MMC) is set as ‘%SystemRoot%\system32\mmc.exe “%1” %*’
By altering this value to ‘C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe’, red teamers can exploit the system’s trust in its native components.
This is the heart of the COM Hijacking process, where the system’s expected behaviour is subtly redirected toward the attacker’s benefit. This change forces any action that would typically launch MMC to instead initiate a PowerShell session.
2. Launching Event Viewer: Once the registry is modified, launching the Event Viewer (or any other MMC-associated utility) under the guise of routine administration activities will, instead, open a PowerShell window. The technique is particularly effective as a persistence mechanism, silently re-executing the payload whenever the host application is launched by that user.
3. Gaining Execution Through the Hijacked Process: The PowerShell session initiated through this hijacked process inherits the security context of the calling application, in this case, Event Viewer. In our example, this gives the attacker a Powershell window running as the current user, providing a platform for executing further malicious activity or ensuring the payload is re-triggered automatically each time the host application is launched as part of normal system use.
Implications of COM Hijacking for Red Teams
- Stealth and Evasion: This technique exemplifies how attackers can leverage built-in Windows functionalities to remain under the radar. It underscores the necessity for organizations to have deep visibility into registry modifications and to monitor the integrity of system configuration settings actively.
- Fileless Attack Vector: COM Hijacking represents a sophisticated fileless attack strategy. Since it operates through registry manipulation and exploits legitimate system processes, it leaves minimal forensic evidence, complicating detection and response efforts.
Mitigating COM Hijacking Threats
To protect against COM Hijacking, organizations should implement robust security measures, including:
- Regular Auditing and Monitoring: Continuously monitor and audit registry changes, especially concerning keys known to be targets for hijacking attempts. Employing advanced threat detection solutions can help identify unusual modifications indicative of a COM Hijacking attempt.
- Principle of Least Privilege: Ensure that users operate under the least privileges necessary for their role. Limit administrative access and utilize UAC to its fullest extent to mitigate unauthorized changes.
- Security Awareness Training: Educate staff about the potential tactics used by attackers, including COM Hijacking, to foster a culture of security mindfulness and vigilance.
- Use of Endpoint Detection and Response (EDR) Tools: Deploy advanced EDR solutions capable of detecting and responding to suspicious activities, including unusual registry modifications and fileless attack techniques.
Conclusion
COM Hijacking is a potent example of how red teams can simulate advanced persistent threats to test and enhance an organization’s defenses. By understanding and preparing for such sophisticated attack vectors, organizations can better safeguard their IT environments against real-world adversaries. This knowledge not only fortifies cybersecurity posture but also aligns with Wizard Cyber‘s mission to empower clients through state-of-the-art defense mechanisms and strategic security insights.
