CVE-2018-3942 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.
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Analysis
by VulDB Data Team • 07/30/2024
The vulnerability identified as CVE-2018-3942 represents a critical use-after-free condition within the JavaScript engine of Foxit PDF Reader version 9.1.0.5096. This type of memory corruption flaw occurs when a program continues to reference memory that has already been freed, creating opportunities for attackers to manipulate program execution flow. The vulnerability specifically affects the JavaScript interpreter component that processes PDF files, making it particularly dangerous as PDF documents are commonly encountered in both personal and enterprise environments. The flaw allows for arbitrary code execution when a malicious PDF is opened, potentially compromising user systems and enabling further attack vectors.
The technical implementation of this vulnerability stems from improper memory management within the JavaScript engine's object lifecycle handling. When processing certain PDF documents, the engine allocates memory for JavaScript objects and subsequently frees them, but fails to properly invalidate references to these objects. This creates a window where an attacker can manipulate the memory layout to cause the freed object to be reallocated and reused in a controlled manner. The use-after-free condition typically manifests through crafted JavaScript code embedded within the PDF that triggers specific memory operations, leading to the execution of malicious code with the privileges of the PDF reader application. This vulnerability aligns with CWE-416, which specifically addresses use-after-free errors in memory management.
The operational impact of CVE-2018-3942 extends beyond simple privilege escalation, as it provides attackers with a pathway to execute arbitrary code on victim systems without requiring local access or elevated privileges. The attack vector requires social engineering to convince users to open malicious PDF files, but once executed, the vulnerability can lead to complete system compromise. Attackers can leverage this vulnerability to install backdoors, exfiltrate sensitive data, or establish persistent access to compromised systems. The vulnerability's exploitation potential makes it particularly attractive to threat actors targeting enterprise environments where PDF documents are frequently shared and opened by multiple users, potentially creating widespread compromise opportunities.
Mitigation strategies for CVE-2018-3942 should prioritize immediate patching of Foxit PDF Reader to version 9.1.1.5100 or later, which contains the necessary memory management fixes to prevent the use-after-free condition. Organizations should implement strict PDF file handling policies, including content filtering and sandboxing mechanisms that isolate PDF processing from the main operating system. Network-level controls such as web application firewalls and email filtering systems can help prevent delivery of malicious PDFs to users. Additionally, security teams should monitor for indicators of compromise related to PDF-based attacks and implement regular security assessments of PDF processing capabilities. The vulnerability's classification under ATT&CK technique T1203 - Exploitation for Client Execution demonstrates the need for comprehensive endpoint protection that addresses both traditional malware and advanced persistent threat vectors targeting client-side applications.