CVE-2018-3940 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. An attacker needs to trick the user to open the malicious file to trigger.
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Analysis
by VulDB Data Team • 05/23/2023
The vulnerability identified as CVE-2018-3940 represents a critical use-after-free flaw within the JavaScript engine of Foxit PDF Reader version 9.1.0.5096. This type of vulnerability occurs when a program continues to reference memory that has already been freed, creating opportunities for malicious exploitation. The issue stems from improper memory management within the JavaScript interpreter that processes PDF files, specifically when handling certain JavaScript commands embedded within PDF documents. The vulnerability manifests when the PDF reader encounters a crafted PDF file containing malicious JavaScript code that manipulates object references in a way that leads to memory corruption. According to CWE-416, this vulnerability maps directly to use-after-free conditions where memory is accessed after it has been freed, creating a potential attack surface for remote code execution.
The technical exploitation of this vulnerability requires an attacker to craft a malicious PDF document that triggers the JavaScript engine to execute specific code patterns that cause objects to be freed from memory while still being referenced. When the JavaScript engine attempts to access these previously freed objects, it can result in memory corruption that allows for arbitrary code execution. The attack vector relies entirely on social engineering since users must be tricked into opening the malicious file, making this a client-side vulnerability that targets end-user systems. The exploitation process involves manipulating the garbage collection mechanisms within the JavaScript engine to ensure that specific objects are freed and then accessed again, potentially allowing for memory overwrite or code injection attacks.
The operational impact of this vulnerability extends beyond simple privilege escalation as it represents a remote code execution threat that can compromise entire user systems. When successfully exploited, the vulnerability allows attackers to execute arbitrary code with the privileges of the user running the PDF reader, potentially leading to complete system compromise. The vulnerability affects a widely used PDF reading application, increasing the potential attack surface significantly. Organizations using Foxit PDF Reader version 9.1.0.5096 are particularly at risk as this version represents a common target for exploitation campaigns. The vulnerability's impact is amplified by the fact that PDF files are commonly shared through email, web downloads, and file transfers, making it a prime target for phishing attacks and malicious document distribution.
Mitigation strategies for CVE-2018-3940 should focus on immediate patching of the Foxit PDF Reader application to the latest version that addresses this specific memory management flaw. System administrators should implement strict document validation policies and consider deploying sandboxing solutions to isolate PDF processing activities. According to ATT&CK framework, this vulnerability aligns with techniques involving exploitation of remote services and client-side application flaws, making network-based detection and prevention measures essential. Organizations should also consider implementing email filtering solutions that can identify and block potentially malicious PDF attachments, as well as user education programs to reduce the success rate of social engineering attacks. The vulnerability highlights the importance of maintaining up-to-date security patches and demonstrates the critical nature of JavaScript engine security in document readers, as these components often have extensive access to system resources and user data.