CVE-2018-16296 in Foxit
Summary
by MITRE
An exploitable use-after-free vulnerability exists in the JavaScript engine of Foxit Reader before 9.3 and PhantomPDF before 9.3, a different vulnerability than CVE-2018-16291, CVE-2018-16292, CVE-2018-16293, CVE-2018-16294, CVE-2018-16295, and CVE-2018-16297. 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-2018-16296 represents a critical use-after-free flaw within the JavaScript engine of Foxit Reader and PhantomPDF applications. This issue affects versions prior to 9.3 and operates as a remote code execution vulnerability that can be triggered through malicious PDF documents. The flaw stems from improper memory management where objects are freed from memory but continue to be referenced, creating a scenario where subsequent memory operations can corrupt or reuse the freed memory space. This particular vulnerability demonstrates the dangerous consequences of memory safety issues in PDF processing engines that handle complex JavaScript functionality within document contexts.
The technical exploitation of this vulnerability involves crafting a malicious PDF document that specifically targets the JavaScript engine's memory management routines. When the vulnerable application processes such a document, the JavaScript engine executes code that causes a specific object to be freed from memory while maintaining references to it. Subsequently, when the application attempts to access or reuse this freed object, it operates on corrupted memory locations that may contain attacker-controlled data. This memory corruption can be manipulated to redirect program execution flow, ultimately allowing an attacker to execute arbitrary code with the privileges of the targeted user. The vulnerability classifies under CWE-416 as a use-after-free condition, which represents a well-known and highly dangerous category of memory safety issues.
The operational impact of CVE-2018-16296 extends beyond simple privilege escalation to encompass full system compromise when exploited successfully. Attackers can leverage this vulnerability through social engineering campaigns that trick users into opening malicious PDF files, making it particularly dangerous in enterprise environments where users frequently handle documents from external sources. The vulnerability becomes even more severe when browser plugin extensions are enabled, as it can be triggered through web-based attacks where visiting a malicious website suffices to exploit the vulnerability. This dual attack surface increases the exploitability of the vulnerability and makes it a significant concern for organizations that rely on PDF processing capabilities in their web browsing environments.
Mitigation strategies for CVE-2018-16296 should prioritize immediate patching of affected versions to Foxit Reader and PhantomPDF applications, with the installation of version 9.3 or later that contains the necessary memory management fixes. Organizations should implement comprehensive endpoint protection measures including sandboxing PDF processing capabilities and restricting access to potentially malicious documents through network-level filtering and email security solutions. Security teams should also consider disabling JavaScript execution in PDF viewers when it is not required for business operations, as this significantly reduces the attack surface. Additionally, regular security awareness training for users can help prevent successful social engineering attacks that rely on tricking individuals into opening malicious PDF files, while monitoring for suspicious PDF-related network activity can provide early detection of exploitation attempts. The vulnerability demonstrates the critical importance of maintaining up-to-date security patches and implementing defense-in-depth strategies to protect against memory corruption vulnerabilities that can lead to complete system compromise.