CVE-2018-17700 in PhantomPDF
Summary
by MITRE
This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Foxit PhantomPDF 9.2.0.9297. 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 Array.prototype.concat. The issue results from the lack of proper validation of user-supplied data, which can result in a read past the end of an allocated object. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-7131.
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Analysis
by VulDB Data Team • 08/01/2024
CVE-2018-17700 represents a critical remote code execution vulnerability affecting Foxit PhantomPDF version 9.2.0.9297, demonstrating a classic buffer overread condition that can be exploited through web-based attacks. This vulnerability resides within the JavaScript engine's implementation of Array.prototype.concat method, where insufficient input validation allows malicious data to trigger memory access violations. The flaw specifically manifests when the application processes user-supplied arrays during concatenation operations, leading to a situation where the application reads memory beyond the bounds of allocated objects. This type of vulnerability falls under CWE-125, which describes out-of-bounds read conditions that can occur when an application accesses memory beyond the intended buffer boundaries.
The attack vector requires user interaction through visiting malicious web pages or opening compromised PDF files, making this a client-side exploit that leverages the browser's PDF rendering capabilities. When a user encounters a crafted PDF document containing malicious JavaScript code, the vulnerable Array.prototype.concat implementation triggers the memory corruption, potentially allowing attackers to execute arbitrary code with the privileges of the running process. This vulnerability directly maps to ATT&CK technique T1059.007 for JavaScript, where adversaries use scripting languages to establish persistence and execute commands. The exploitation process typically involves crafting a PDF file that, when opened, triggers the vulnerable JavaScript functionality through a malicious array manipulation sequence that causes the buffer overread condition.
The operational impact of this vulnerability extends beyond simple code execution, as it can enable full system compromise when combined with other attack vectors or when the target application runs with elevated privileges. The vulnerability affects the PDF rendering engine's JavaScript interpreter, which means that any PDF document processed by the vulnerable application could potentially serve as an attack vector. Attackers can leverage this weakness to install malware, steal sensitive information, or establish persistent access to affected systems. The vulnerability's classification as a remote code execution flaw means that attackers do not require physical access to the target system, making it particularly dangerous in enterprise environments where users frequently open PDF documents from untrusted sources.
Organizations should implement immediate mitigations including updating to patched versions of Foxit PhantomPDF, implementing web application firewalls to filter malicious PDF content, and deploying sandboxing solutions to isolate PDF processing activities. Additionally, security teams should monitor for suspicious PDF files and implement user education programs to reduce the risk of successful exploitation through social engineering attacks. The vulnerability demonstrates the importance of proper input validation and memory management in JavaScript engines, particularly when handling array operations that could lead to memory corruption. Security professionals should also consider implementing network segmentation and access controls to limit the potential impact of successful exploitation attempts.