CVE-2011-3690 in PDFill PDF Editor
Summary
by MITRE
Untrusted search path vulnerability in PlotSoft PDFill PDF Editor 8.0 allows local users to gain privileges via a Trojan horse mfc70enu.dll or mfc80loc.dll in the current working directory.
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Analysis
by VulDB Data Team • 01/17/2018
The vulnerability identified as CVE-2011-3690 represents a critical untrusted search path issue within PlotSoft PDFill PDF Editor version 8.0, which creates a privilege escalation vector for local attackers. This flaw stems from the application's improper handling of dynamic library loading mechanisms, specifically when searching for required DLL components in the current working directory rather than following secure path resolution practices. The vulnerability is classified under CWE-427, which describes Untrusted Search Path, and aligns with ATT&CK technique T1068, which covers Local Privilege Escalation through malicious DLL injection.
The technical exploitation of this vulnerability occurs when a local attacker places a malicious Trojan horse DLL file named either mfc70enu.dll or mfc80loc.dll in the same directory as the vulnerable PDFill application. When the application executes and attempts to load these specific library components, it inadvertently loads the attacker-controlled DLL instead of the legitimate system libraries. The mfc70enu.dll and mfc80loc.dll files are legitimate Microsoft Foundation Class libraries that PDFill may attempt to load during normal operation, making this attack vector particularly stealthy as the malicious DLL appears to be a legitimate component. This behavior violates the principle of least privilege and enables attackers to execute arbitrary code with the privileges of the user running the vulnerable application.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential full system compromise when the vulnerable application runs with elevated permissions. Since PDFill is a PDF editing tool that may be executed by users with varying privilege levels, attackers can leverage this weakness to gain unauthorized access to system resources, modify or exfiltrate sensitive documents, and potentially establish persistent access through the compromised application. The vulnerability is particularly concerning in enterprise environments where users may have elevated privileges or where the application is used to process sensitive corporate documents, as it provides an attack surface that can be exploited without requiring network access or complex exploitation techniques.
Mitigation strategies for CVE-2011-3690 should focus on both immediate remediation and long-term architectural improvements. The most effective immediate solution involves applying the vendor-supplied patch or upgrading to a newer version of PDFill that addresses this untrusted search path vulnerability. Organizations should also implement strict file access controls and audit the current working directory permissions for the vulnerable application, ensuring that only authorized users can write to these locations. Additionally, system administrators should consider implementing application whitelisting policies that restrict which DLLs can be loaded by the PDFill application, and conduct regular security audits to identify other applications with similar untrusted search path vulnerabilities. The use of security tools that monitor for suspicious DLL loading behavior can also provide early detection of exploitation attempts, while regular security awareness training can help users recognize potential social engineering attacks that might accompany such exploitation attempts.