CVE-2014-8396 in PDF Fusion
Summary
by MITRE
Untrusted search path vulnerability in Corel PDF Fusion allows local users to execute arbitrary code and conduct DLL hijacking attacks via a Trojan horse quserex.dll file that is located in the same folder as the file being processed.
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Analysis
by VulDB Data Team • 06/17/2017
The vulnerability identified as CVE-2014-8396 represents a critical untrusted search path issue within Corel PDF Fusion software that exposes systems to arbitrary code execution and DLL hijacking attacks. This flaw specifically affects the application's handling of file processing workflows where it fails to properly validate the security context of dynamically loaded libraries. The vulnerability arises when Corel PDF Fusion processes files in a directory containing malicious DLL files, creating an environment where attackers can leverage the application's trusted search order to load unauthorized code.
The technical exploitation of this vulnerability occurs through a Trojan horse approach where attackers place a malicious quserex.dll file in the same directory as a target file being processed by the application. This malicious DLL is designed to masquerade as a legitimate system component, taking advantage of the application's default search path behavior that prioritizes local directories over system paths. When Corel PDF Fusion attempts to load the required library components during file processing, it inadvertently loads the malicious quserex.dll instead of the legitimate system library, thereby executing attacker-controlled code within the application's security context.
From an operational impact perspective, this vulnerability enables local attackers to gain elevated privileges and execute arbitrary commands on affected systems. The attack vector is particularly concerning because it requires minimal user interaction beyond the simple act of processing a malicious file, making it highly exploitable in both targeted and mass attack scenarios. The vulnerability affects systems where Corel PDF Fusion is installed and actively used for document processing, creating a persistent threat vector that can be leveraged for privilege escalation, data exfiltration, or further system compromise.
The vulnerability aligns with CWE-427 Uncontrolled Search Path Element, which specifically addresses the risk of applications loading libraries from untrusted directories in their search path. This weakness falls under the broader category of DLL hijacking attacks that are systematically catalogued in the MITRE ATT&CK framework under the technique T1574.001 - DLL Side-Loading, which describes how attackers can abuse legitimate system processes to load malicious DLLs. The attack pattern is further reinforced by the common practice of placing malicious libraries in directories that are prioritized in the Windows search order, allowing attackers to bypass security controls that might otherwise prevent execution of malicious code.
Mitigation strategies for CVE-2014-8396 should focus on implementing proper input validation and library loading practices within Corel PDF Fusion. Organizations should ensure that applications employ secure coding practices such as specifying full paths to required libraries, implementing proper DLL loading mechanisms that avoid untrusted search paths, and applying the principle of least privilege to reduce the impact of potential exploitation. System administrators should consider restricting write access to directories containing Corel PDF Fusion executables and their associated files, while also implementing application whitelisting policies that prevent execution of unauthorized DLL files. Additionally, regular security updates and patches from Corel should be applied promptly to address this vulnerability and prevent exploitation attempts that rely on the untrusted search path behavior.