CVE-2018-6218 in User-Mode Hooking Module
Summary
by MITRE
A DLL Hijacking vulnerability in Trend Micro's User-Mode Hooking Module (UMH) could allow an attacker to run arbitrary code on a vulnerable system.
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Analysis
by VulDB Data Team • 01/06/2020
The vulnerability identified as CVE-2018-6218 represents a critical DLL hijacking flaw within Trend Micro's User-Mode Hooking Module (UMH) component, which operates at the user level within the Windows operating system environment. This vulnerability stems from improper handling of dynamic link library loading sequences, creating opportunities for malicious code execution through strategic placement of attacker-controlled DLL files in predictable system paths. The UMH module is designed to intercept and monitor user-mode system calls, making it a prime target for privilege escalation attacks that could compromise entire systems.
The technical exploitation of this vulnerability occurs when the Trend Micro UMH module attempts to load required dynamic link libraries without properly validating the full path of the requested modules. Attackers can leverage this weakness by placing malicious DLL files in directories that are searched before the legitimate system directories, a technique known as DLL preloading or DLL hijacking. The flaw specifically affects systems where Trend Micro software is installed, particularly those running Windows operating systems where the module operates with elevated privileges. This creates a dangerous scenario where any user with access to the system could potentially place malicious code that would execute with the privileges of the Trend Micro service, which typically runs with high system privileges.
The operational impact of CVE-2018-6218 extends beyond simple code execution, as it provides a potential pathway for attackers to escalate privileges and establish persistent access within compromised environments. The vulnerability can be exploited through various attack vectors including social engineering techniques that trick users into executing malicious payloads, or through direct compromise of systems where Trend Micro is installed. Security researchers have noted that this vulnerability aligns with CWE-426, which describes the weakness of untrusted search path, and it maps to ATT&CK technique T1055, specifically DLL hijacking. The risk is particularly elevated in enterprise environments where Trend Micro products are widely deployed, as successful exploitation could lead to complete system compromise and data exfiltration.
Mitigation strategies for CVE-2018-6218 require immediate attention from system administrators and security teams responsible for Trend Micro installations. The primary recommendation involves applying the vendor-provided security patches that address the DLL loading behavior within the UMH module, ensuring that all systems running Trend Micro software are updated to the latest versions. Additionally, implementing proper file system permissions and access controls can help reduce the attack surface by preventing unauthorized users from placing DLL files in critical system directories. Network segmentation and monitoring solutions should be deployed to detect anomalous behavior that might indicate exploitation attempts, while security awareness training for users can help prevent social engineering attacks that might leverage this vulnerability. The remediation process should include thorough system audits to identify and remove any unauthorized DLL files that might have been placed on affected systems, and continuous monitoring for suspicious file placement activities in system directories that could indicate ongoing exploitation attempts.