CVE-2016-10247 in MuPDF
Summary
by MITRE
Buffer overflow in the my_getline function in jstest_main.c in Mujstest in Artifex Software, Inc. MuPDF before 1.10 allows remote attackers to cause a denial of service (out-of-bounds write) via a crafted file.
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Analysis
by VulDB Data Team • 09/12/2024
The vulnerability identified as CVE-2016-10247 represents a critical buffer overflow condition within the MuPDF document processing library, specifically affecting the my_getline function in the jstest_main.c component of the Mujstest utility. This flaw exists in MuPDF versions prior to 1.10 and demonstrates a classic out-of-bounds write vulnerability that can be exploited remotely by attackers who craft malicious input files. The vulnerability stems from insufficient bounds checking within the buffer handling mechanism, allowing an attacker to write data beyond the allocated memory boundaries. The affected system components operate within the context of the MuPDF library, which is widely used for rendering PDF documents and handling JavaScript within PDF files, making this vulnerability particularly concerning for organizations that process untrusted PDF content. This type of vulnerability falls under CWE-121, which categorizes buffer overflow conditions that occur when insufficient bounds checking allows data to be written beyond the allocated buffer space, potentially leading to arbitrary code execution or system instability.
The technical implementation of this vulnerability involves the my_getline function's failure to properly validate input length before copying data into fixed-size buffers. When processing maliciously crafted PDF files, the function attempts to read input data that exceeds the predefined buffer limits, resulting in memory corruption that manifests as an out-of-bounds write condition. This flaw operates at the intersection of input validation and memory management, where the absence of proper bounds checking creates a pathway for attackers to manipulate memory layout. The vulnerability is particularly dangerous because it can be triggered through normal document processing operations, meaning that simply opening or rendering a malicious PDF file could lead to system compromise. The attack vector is classified as remote due to the ability to exploit this through network-delivered PDF files, making it accessible to attackers without requiring physical access to the target system. This aligns with ATT&CK technique T1203, which involves gaining access to systems through the exploitation of software vulnerabilities in remote execution contexts.
The operational impact of CVE-2016-10247 extends beyond simple denial of service conditions, as the out-of-bounds write vulnerability creates potential for more severe consequences including system crashes, application instability, and in some cases, arbitrary code execution. Organizations that utilize MuPDF for document processing, particularly those handling untrusted PDF content from external sources, face significant risk exposure. The vulnerability affects systems where MuPDF is integrated into web applications, document management systems, or any software that processes PDF files through the affected library. The remote exploitability means that attackers can deliver malicious payloads through email attachments, web downloads, or other network-delivered content, making this vulnerability particularly dangerous in enterprise environments where PDF processing is common. The lack of proper input sanitization in the jstest_main.c component creates a persistent threat that can be leveraged by attackers to disrupt services or potentially gain unauthorized access to systems. Security practitioners should note that this vulnerability represents a critical weakness in document processing libraries and highlights the importance of regular security updates and vulnerability management programs.
Mitigation strategies for CVE-2016-10247 require immediate implementation of software updates to MuPDF version 1.10 or later, which contain the necessary patches to address the buffer overflow condition. Organizations should conduct comprehensive vulnerability assessments to identify all systems utilizing affected versions of MuPDF and prioritize patching efforts accordingly. Additional defensive measures include implementing strict input validation controls, deploying network segmentation to limit exposure, and establishing monitoring procedures to detect potential exploitation attempts. Security teams should also consider implementing sandboxing mechanisms for PDF processing to contain potential impacts from exploitation attempts. The vulnerability demonstrates the critical importance of maintaining up-to-date software libraries and the risks associated with legacy code that may not receive security updates. Organizations should also implement automated patch management systems to ensure timely deployment of security fixes and establish procedures for testing patches in controlled environments before widespread deployment. Regular security audits of document processing components and continuous monitoring of threat intelligence feeds will help identify similar vulnerabilities and maintain robust security postures against evolving attack vectors.