CVE-2017-14827 in Foxit
Summary
by MITRE
This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Foxit Reader 8.3.1.21155. 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 append method of XFA Node objects. The issue results from the lack of proper validation of user-supplied data, which can result in a type confusion condition. An attacker can leverage this vulnerability to execute code under the context of the current process. Was ZDI-CAN-5019.
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Analysis
by VulDB Data Team • 12/16/2019
CVE-2017-14827 represents a critical type confusion vulnerability affecting Foxit Reader version 8.3.1.21155 that enables remote code execution through crafted XFA Node objects. This vulnerability resides within the append method of XFA Node objects where insufficient input validation permits malicious data to corrupt memory structures and manipulate object type information during runtime operations. The flaw stems from improper handling of user-supplied data that flows through the XFA (XML Forms Architecture) processing engine, creating conditions where the application incorrectly interprets data types leading to arbitrary code execution. The vulnerability requires user interaction to exploit, meaning attackers must convince victims to visit malicious web pages or open specially crafted PDF files containing the malicious XFA content. This attack vector aligns with common social engineering techniques frequently employed in targeted attacks against enterprise environments where users may encounter compromised content through email attachments or web browsing activities. The type confusion aspect of this vulnerability places it squarely within CWE-843, which specifically addresses "Access of Resource Using Incompatible Type" and represents a fundamental flaw in type safety mechanisms. The attack leverages the inherent complexity of XFA processing where multiple data types and object models interact, creating opportunities for attackers to manipulate object pointers and memory layouts. When exploited, this vulnerability allows attackers to execute code within the security context of the Foxit Reader process, potentially enabling full system compromise if the application runs with elevated privileges. The exploitation process typically involves crafting malicious XFA content that triggers the vulnerable append method, causing the application to misinterpret data as different object types and subsequently execute attacker-controlled code. This vulnerability demonstrates the risks associated with complex document processing engines that must handle diverse data formats and maintain strict type safety boundaries. The impact extends beyond simple code execution as the compromised process may have access to the user's file system, network resources, and potentially sensitive data processed through the vulnerable application. Security researchers have documented similar type confusion vulnerabilities in other PDF processing libraries, highlighting the persistent challenge of maintaining memory safety in complex document rendering engines. Organizations should prioritize patching this vulnerability immediately, as it represents a significant risk to enterprise security environments where PDF documents are frequently processed and shared. The vulnerability's remote exploitation capability makes it particularly dangerous in targeted attack scenarios where adversaries can deploy malicious content through web-based delivery mechanisms. Mitigation strategies should include immediate deployment of vendor patches, network-based filtering of suspicious PDF content, and user education to avoid opening untrusted documents. Additionally, implementing application whitelisting policies and sandboxing mechanisms can provide additional defense layers against exploitation attempts. The vulnerability underscores the importance of rigorous input validation and type safety checking in document processing applications, particularly those handling complex markup languages like XFA that require extensive runtime type management and object model manipulation.