CVE-2018-3944 in Foxit
Summary
by MITRE
An exploitable use-after-free vulnerability exists in the JavaScript engine of Foxit Software's 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. 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-2018-3944 represents a critical use-after-free flaw within the JavaScript engine of Foxit PDF Reader version 9.1.0.5096, classified under CWE-416 as use of freed memory. This type of vulnerability occurs when a program continues to reference memory that has already been freed, creating opportunities for memory corruption and arbitrary code execution. The flaw exists in the browser plugin extension functionality that allows PDF documents to be rendered directly within web browsers, making it particularly dangerous as it can be exploited through web-based attacks rather than requiring local file execution. The vulnerability demonstrates the inherent risks associated with complex JavaScript engines embedded in document readers, where memory management errors can be leveraged by attackers to gain unauthorized system control.
The technical exploitation of this vulnerability requires careful crafting of a malicious PDF document that triggers specific memory allocation patterns within the Foxit Reader's JavaScript engine. When the vulnerable software processes the crafted PDF, it allocates memory for JavaScript objects, frees them during normal operation, but then allows subsequent code to reference these previously freed memory locations. This memory reuse creates a condition where attackers can overwrite critical memory structures with malicious code, effectively hijacking the execution flow of the application. The attack vector is particularly concerning because it can be delivered through both direct file manipulation and web-based delivery methods, exploiting the browser plugin extension that enables PDF rendering in web environments. The vulnerability demonstrates the complex interaction between memory management, JavaScript interpretation, and web browser integration that creates opportunities for sophisticated exploitation techniques.
The operational impact of CVE-2018-3944 extends beyond simple privilege escalation to encompass complete system compromise, as arbitrary code execution allows attackers to install malware, steal sensitive data, or establish persistent backdoors. The vulnerability affects users who have enabled the browser plugin extension, making it particularly dangerous in enterprise environments where PDF viewing is common and web-based attacks are prevalent. Security researchers have noted that this type of vulnerability is particularly challenging to detect and prevent because it operates at the intersection of multiple security boundaries, involving both application-level memory management and web browser security models. The exploitation process typically requires advanced knowledge of memory layout and exploitation techniques, but the vulnerability's accessibility through web browsers makes it a prime target for automated exploitation frameworks.
Mitigation strategies for CVE-2018-3944 primarily focus on immediate patching and configuration changes to prevent exploitation. Users should immediately update to Foxit Reader version 9.1.1.5100 or later, which contains the necessary memory management fixes to prevent the use-after-free condition. Organizations should disable the browser plugin extension in Foxit Reader when it is not required, reducing the attack surface available to web-based exploitation attempts. Network security measures including web filtering and sandboxing can provide additional protection layers, though these are secondary to the primary patching requirement. The vulnerability highlights the importance of keeping document reader software updated, particularly in environments where PDF documents are frequently opened from untrusted sources. Security teams should also implement monitoring for unusual PDF processing behavior and consider implementing application whitelisting policies to restrict execution of potentially vulnerable software versions. This vulnerability serves as a reminder of the critical importance of memory safety in software development, particularly for applications handling untrusted input data, and aligns with ATT&CK techniques related to exploitation of memory corruption vulnerabilities and privilege escalation through application execution.