CVE-2021-31442 in Foxit
Summary
by MITRE • 05/08/2021
This vulnerability allows remote attackers to execute arbitrary code on affected installations of Foxit Reader 10.1.1.37576. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within the handling of U3D objects in PDF files. The issue results from the lack of proper validation of user-supplied data, which can result in a write past the end of an allocated data structure. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-13239.
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Analysis
by VulDB Data Team • 05/12/2021
CVE-2021-31442 represents a critical buffer overflow vulnerability affecting Foxit Reader version 10.1.1.37576 that enables remote code execution through maliciously crafted PDF files containing U3D objects. This vulnerability operates under the Common Weakness Enumeration classification of CWE-121, which encompasses heap-based buffer overflow conditions where insufficient bounds checking allows attackers to write beyond allocated memory boundaries. The flaw specifically manifests during the processing of Universal 3D (U3D) objects within PDF documents, which are used to embed three-dimensional graphics and models in portable document format files.
The technical implementation of this vulnerability stems from inadequate input validation mechanisms within Foxit Reader's PDF parsing engine. When the application encounters a U3D object embedded in a PDF file, it fails to properly validate the size and boundaries of the incoming data structure before attempting to write to memory locations. This insufficient validation creates a predictable memory corruption scenario where attacker-controlled data can overwrite adjacent memory regions, potentially including executable code or critical program pointers. The vulnerability is particularly dangerous because it requires only user interaction through visiting a malicious webpage or opening a crafted PDF document, making it highly exploitable in phishing campaigns or drive-by download attacks.
From an operational impact perspective, successful exploitation of this vulnerability allows remote attackers to execute arbitrary code within the context of the Foxit Reader process, effectively compromising the victim's system. The attack vector demonstrates characteristics consistent with the MITRE ATT&CK framework's technique T1203, which involves exploitation of remote services through web-based attacks, and T1059, which covers command and scripting interpreter usage for execution. The compromised process typically runs with the privileges of the user who opened the malicious document, potentially enabling further lateral movement or privilege escalation within the compromised environment. Organizations relying on Foxit Reader for document viewing are particularly vulnerable since the application's widespread use across various industries creates a substantial attack surface.
Security mitigation strategies for CVE-2021-31442 should prioritize immediate patch deployment from Foxit Corporation, as the vendor has released updated versions addressing this specific buffer overflow condition. Network administrators should implement content filtering solutions to block PDF files from untrusted sources and consider deploying sandboxing technologies to isolate PDF processing activities. Additionally, user education programs should emphasize the importance of avoiding suspicious email attachments and visiting unverified websites that may contain malicious PDF content. Organizations should also consider implementing application whitelisting policies that restrict the execution of unauthorized PDF readers or disable U3D object processing entirely within their security policies to minimize exposure to this class of vulnerability.