CVE-2010-5245 in PDF-XChange
Summary
by MITRE
Untrusted search path vulnerability in PDF-XChange Viewer 2.0 Build 54.0 allows local users to gain privileges via a Trojan horse wintab32.dll file in the current working directory, as demonstrated by a directory that contains a .pdf file. NOTE: some of these details are obtained from third party information.
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Analysis
by VulDB Data Team • 02/20/2019
The vulnerability identified as CVE-2010-5245 represents a critical untrusted search path weakness in PDF-XChange Viewer version 2.0 Build 54.0 that enables local privilege escalation through malicious DLL hijacking. This flaw resides in the application's dynamic link library loading mechanism, where the software fails to properly validate the source and authenticity of dynamically loaded components. The vulnerability operates under the Common Weakness Enumeration classification of CWE-427 Uncontrolled Search Path Element, which specifically addresses situations where applications search for libraries in predictable locations without adequate security controls. The attack vector is particularly insidious because it leverages the Windows DLL search order mechanism, where the system first searches the current working directory before examining system directories, creating an opportunity for malicious actors to place crafted DLL files in strategic locations.
The technical exploitation of this vulnerability occurs when a user opens a PDF file in a directory containing a malicious wintab32.dll file. The PDF-XChange Viewer application, during its normal operation, attempts to load the wintab32.dll library from the current working directory, which the attacker has controlled. This creates a privilege escalation scenario where a local user can execute arbitrary code with the privileges of the target application. The vulnerability is particularly concerning because it does not require any user interaction beyond opening a PDF file, making it a latent threat that can be triggered automatically. The attack follows the ATT&CK framework's technique T1059 Command and Scripting Interpreter and T1068 Exploitation for Privilege Escalation, where the malicious DLL execution is facilitated through legitimate application pathways.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with a persistent foothold within the target system. When the PDF viewer loads the malicious DLL, it can establish backdoor connections, escalate privileges, or perform reconnaissance activities without detection. The vulnerability affects Windows systems where PDF-XChange Viewer is installed and where users have the ability to create files in directories containing PDF documents. The risk is amplified because many users operate with elevated privileges when opening documents, and the application's legitimate use of the Windows API for tablet functionality creates a legitimate code path that attackers can exploit. This vulnerability also demonstrates the broader issue of insecure library loading practices that affect numerous applications across different platforms, making it a significant concern for enterprise security and compliance with standards such as NIST SP 800-171.
Mitigation strategies for this vulnerability must address both the immediate threat and prevent similar issues in the future. Organizations should implement strict access controls to prevent unauthorized file creation in directories containing sensitive documents, particularly those where PDF viewers are commonly used. The most effective immediate solution involves updating to a patched version of PDF-XChange Viewer that properly implements secure library loading mechanisms and validates DLL sources. System administrators should also consider implementing application whitelisting policies that restrict which DLLs can be loaded by the viewer application. Additionally, users should be educated about the risks of opening PDF files from untrusted sources and the importance of maintaining secure working directories. The vulnerability highlights the importance of proper software development practices including secure coding guidelines, static code analysis, and regular security testing to prevent similar issues from occurring in other applications. Organizations should also monitor for similar vulnerabilities in other PDF viewers and document management software, as this type of attack vector is commonly found in legacy applications that do not properly implement modern security controls.