CVE-2018-3957 in Foxit
Summary
by MITRE
A use-after-free vulnerability exists in the JavaScript engine of Foxit Software's Foxit PDF Reader version 9.1.0.5096. A use-after-free condition can occur when accessing the Keywords property of the this.info object. An attacker needs to trick the user to open the malicious file to trigger this vulnerability. If the browser plugin extension is enabled, visiting a malicious site can also trigger the vulnerability.
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Analysis
by VulDB Data Team • 07/30/2024
The vulnerability identified as CVE-2018-3957 represents a critical use-after-free condition within Foxit Software's PDF Reader application, specifically affecting version 9.1.0.5096. This flaw resides in the JavaScript engine component that processes PDF documents, creating a pathway for remote code execution when malicious content is processed. The vulnerability manifests when accessing the Keywords property of the this.info object within the PDF's JavaScript context, where improper memory management allows for the reuse of freed memory locations. The attack vector requires user interaction through opening a malicious PDF file, though the presence of browser plugin extensions expands the attack surface to include web-based exploitation when users visit compromised websites.
The technical nature of this vulnerability aligns with CWE-416, which categorizes use-after-free conditions as a memory safety issue where memory that has been freed is accessed again. This specific implementation flaw occurs within the JavaScript engine's object handling mechanisms, where the Keywords property of the this.info object does not properly validate memory references before access. When a malicious PDF document is processed, the engine allocates memory for the Keywords property, processes it, and then frees the memory location. However, subsequent access to this freed memory location through the JavaScript engine's execution path creates an opportunity for memory corruption that can be exploited by attackers. The vulnerability demonstrates a classic memory safety issue where the JavaScript engine fails to maintain proper reference counting or memory lifecycle management for dynamic objects.
The operational impact of CVE-2018-3957 extends beyond simple privilege escalation as it provides attackers with a remote code execution capability that can be leveraged for full system compromise. The vulnerability's exploitation requires user interaction, making it particularly dangerous in targeted attack scenarios where social engineering can be employed to deliver malicious PDF files. When successfully exploited, the use-after-free condition can lead to arbitrary code execution with the privileges of the PDF reader process, potentially allowing attackers to install malware, steal sensitive data, or establish persistent access to affected systems. The browser plugin extension component further amplifies the risk by enabling exploitation through web browsers, where users may unknowingly visit compromised websites that deliver the malicious payload through PDF rendering.
Mitigation strategies for this vulnerability should prioritize immediate patching of Foxit PDF Reader to versions that address the memory management flaw in the JavaScript engine. Organizations should implement strict document review processes for PDF files, particularly those received from untrusted sources, and consider deploying sandboxing solutions that isolate PDF processing from the main operating system. Network-based protections including web application firewalls and content filtering systems can help block access to known malicious PDF files and suspicious websites. Security teams should also consider disabling browser plugin extensions for PDF viewing when possible, as this reduces the attack surface for web-based exploitation. The vulnerability highlights the importance of maintaining up-to-date software versions and implementing defense-in-depth strategies, as the use-after-free condition represents a fundamental memory safety issue that can be exploited to achieve complete system compromise. Organizations should also monitor for related vulnerabilities in similar PDF processing engines and maintain comprehensive incident response procedures to address potential exploitation attempts.