Source: security@trendmicro.com
An engine link following vulnerability in Trend Micro Apex One could allow a local attacker to escalate privileges on affected installations. Please note: an attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.
Trend Micro Apex One is vulnerable to a local privilege escalation due to an engine link following vulnerability. An attacker with initial low-level access can leverage this flaw to gain system-level privileges, potentially leading to complete system compromise and data exfiltration. This vulnerability requires an attacker to first gain the ability to execute low-privileged code on the target system.
Step 1: Initial Access: The attacker must first gain the ability to execute low-privileged code on the target system. This could be achieved through various means, such as exploiting another vulnerability, social engineering, or a compromised account.
Step 2: Crafting the Malicious Link: The attacker crafts a malicious engine link. This link will point to a privileged resource or executable that, when followed by the Apex One service, will grant the attacker elevated privileges. This could involve creating a symbolic link to a sensitive file or a path traversal attack to overwrite a critical system file.
Step 3: Payload Placement (Optional): If the malicious link points to an executable, the attacker may need to place a malicious payload (e.g., a reverse shell, a rootkit) at the target location.
Step 4: Triggering the Vulnerability: The attacker triggers the vulnerability by causing the Apex One service to process the malicious engine link. This could involve uploading a crafted configuration file or triggering an update process.
Step 5: Privilege Escalation: The Apex One service follows the malicious link, executing the attacker's code with elevated privileges (e.g., SYSTEM). This allows the attacker to gain full control of the system.
The vulnerability lies within Trend Micro Apex One's engine link following functionality. The software likely processes engine updates or configuration files that contain links or references to other components or files. The flaw stems from insufficient validation or sanitization of these links. Specifically, the software fails to properly verify the destination of these links, allowing a local attacker to craft a malicious link that points to a privileged resource or executable. This could be achieved through a variety of techniques, such as path traversal or symbolic link manipulation. The root cause is a lack of proper input validation and access control checks when processing these engine links, leading to an unintended execution path with elevated privileges. The vulnerability is triggered when the Apex One service attempts to follow the attacker-controlled link, thereby executing the attacker's code with system-level permissions.
While no specific APT groups are known to be actively exploiting this vulnerability, the potential for privilege escalation makes it attractive to various threat actors. The lack of a public PoC suggests that exploitation is likely limited to targeted attacks. CISA KEV status: Not Listed.
Monitor file system activity for the creation or modification of files within the Apex One installation directory, especially those related to engine updates or configuration.
Analyze process creation events for suspicious processes spawned by the Apex One service, particularly those with elevated privileges.
Examine network traffic for unusual outbound connections originating from the Apex One server.
Review system logs (Windows Event Logs, etc.) for errors or warnings related to engine updates or file access within the Apex One directory.
Implement file integrity monitoring (FIM) to detect unauthorized changes to critical system files.
Apply the vendor-provided patch immediately. This is the most effective mitigation.
Implement strong access controls to limit the ability of low-privileged users to execute code on the system.
Regularly audit and review system configurations and security settings.
Implement a robust intrusion detection and prevention system (IDPS) to monitor for malicious activity.
Enforce the principle of least privilege, ensuring that users and services only have the necessary permissions.
Conduct regular vulnerability scans and penetration testing to identify and address security weaknesses.