CVE-2018-3997 in Foxit
Summary
by MITRE
An exploitable use-after-free vulnerability exists in the JavaScript engine of Foxit Software's Foxit PDF Reader, version 9.2.0.9297. 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 • 07/31/2024
The vulnerability identified as CVE-2018-3997 represents a critical use-after-free flaw within the JavaScript engine of Foxit PDF Reader version 9.2.0.9297, classified under CWE-416 as use of freed memory. This vulnerability resides in the browser plugin extension functionality of the PDF reader, which allows for dynamic execution of JavaScript code within PDF documents. The flaw manifests when a malicious PDF document is processed by the vulnerable software, specifically targeting the memory management mechanisms that handle object lifecycle management within the JavaScript engine. The vulnerability operates through a sophisticated attack vector where an attacker crafts a PDF file containing malicious JavaScript code that deliberately triggers the freeing of memory objects while simultaneously setting up conditions for their subsequent reuse. This particular implementation of the use-after-free vulnerability demonstrates the dangerous potential for remote code execution when the PDF reader processes the malicious document.
The technical exploitation of this vulnerability requires careful crafting of PDF structures that manipulate the JavaScript engine's garbage collection behavior. When the vulnerable PDF reader processes the malicious document, it executes JavaScript code that causes specific memory objects to be freed from the heap memory. However, due to insufficient memory management checks, the application continues to reference these freed objects in subsequent operations, leading to a state where the freed memory can be reallocated and accessed by malicious code. This creates an opportunity for attackers to inject and execute arbitrary code with the privileges of the user running the vulnerable software. The attack can be delivered through user interaction via opening a malicious PDF file or through browser plugin execution when visiting compromised websites, making the attack surface particularly broad. The vulnerability specifically targets the JavaScript engine's memory management system, where the freed memory objects can be manipulated to point to attacker-controlled data, enabling code execution in the context of the PDF reader process.
The operational impact of CVE-2018-3997 extends beyond simple privilege escalation to encompass full system compromise capabilities, particularly when considering the ATT&CK framework's techniques for privilege escalation and execution. An attacker exploiting this vulnerability can execute arbitrary code with the same privileges as the PDF reader application, potentially leading to complete system compromise. The vulnerability's reliance on user interaction makes it particularly dangerous in targeted attack scenarios where social engineering can be employed to deliver the malicious PDF document. The browser plugin extension aspect of the vulnerability significantly increases the attack surface, as web-based attacks can be executed without requiring physical access to the target system. Organizations running vulnerable versions of Foxit PDF Reader face substantial risk, as the exploitation can occur through legitimate web browsing activities or through email attachments, making traditional security controls potentially insufficient against this threat vector.
Mitigation strategies for CVE-2018-3997 should prioritize immediate software updates to versions that address the memory management flaws in the JavaScript engine. System administrators should disable the browser plugin extension functionality if it is not essential for business operations, as this removes one of the primary attack vectors for exploitation. Network-level defenses can include PDF content filtering and sandboxing mechanisms that isolate PDF processing from the primary operating system environment. Additionally, user education programs should emphasize the importance of avoiding suspicious PDF attachments and websites, while endpoint protection solutions should be configured to monitor for suspicious JavaScript execution patterns within PDF documents. The vulnerability demonstrates the importance of maintaining current software versions and implementing layered security controls, as the use-after-free flaw represents a fundamental memory safety issue that requires comprehensive remediation through official software updates and security patches. Organizations should also consider implementing network segmentation and access controls to limit the potential impact of successful exploitation attempts.