CVE-2018-3941 in Foxit
Summary
by MITRE
An exploitable use-after-free vulnerability exists in the JavaScript engine of Foxit Software's Foxit PDF Reader version 9.1.0.5096. A specially crafted PDF document can trigger a previously freed object in memory to be reused, resulting in arbitrary code execution. An attacker needs to trick the user to open the malicious file to trigger this vulnerability.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 07/30/2024
The vulnerability identified as CVE-2018-3941 represents a critical use-after-free flaw within the JavaScript engine of Foxit PDF Reader version 9.1.0.5096. This type of vulnerability occurs when a program continues to reference memory locations after they have been freed, creating opportunities for malicious code execution. The flaw specifically affects the browser-based JavaScript engine component that processes PDF documents, making it particularly dangerous as it can be triggered through standard PDF file handling operations.
The technical exploitation of this vulnerability requires a carefully crafted malicious PDF document that manipulates the JavaScript engine's memory management processes. When the vulnerable PDF reader processes such a document, it executes JavaScript code that causes a specific object to be freed from memory while maintaining references to it. Subsequently, when the program attempts to access this previously freed memory location, it triggers undefined behavior that can be exploited to execute arbitrary code with the privileges of the victim user. This memory corruption scenario directly aligns with CWE-416, which describes the use of freed memory vulnerability category.
The operational impact of this vulnerability extends beyond simple code execution, as it represents a complete compromise of the affected system. Attackers can leverage this flaw to install malware, steal sensitive data, or establish persistent access to victim systems. The attack vector requires social engineering to trick users into opening the malicious PDF file, but once executed, the vulnerability provides a powerful foothold for further exploitation. This aligns with ATT&CK technique T1059.007 for JavaScript execution and T1068 for local privilege escalation.
Security practitioners must understand that this vulnerability demonstrates the inherent risks associated with complex JavaScript engines embedded in document readers. The exploitation process involves sophisticated memory manipulation techniques that require deep understanding of both the target application's architecture and the underlying operating system memory management. Organizations should prioritize immediate patching of all affected Foxit PDF Reader installations and implement additional security controls such as PDF sandboxing, application whitelisting, and user education programs to reduce the attack surface. The vulnerability also highlights the importance of regular security assessments and vulnerability management processes to identify and remediate similar flaws in other PDF processing applications.