CVE-2017-7863 in FFmpeg
Summary
by MITRE
FFmpeg before 2017-02-04 has an out-of-bounds write caused by a heap-based buffer overflow related to the decode_frame_common function in libavcodec/pngdec.c.
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Analysis
by VulDB Data Team • 11/29/2022
The vulnerability identified as CVE-2017-7863 represents a critical heap-based buffer overflow in the FFmpeg multimedia framework that was addressed in the February 4, 2017 release. This flaw specifically affects the decode_frame_common function within the PNG decoder component located in libavcodec/pngdec.c, making it a target for exploitation in scenarios involving maliciously crafted PNG image files. The vulnerability stems from insufficient bounds checking during the decoding process, where the application fails to properly validate input data before writing to allocated memory buffers. This particular implementation flaw allows attackers to manipulate memory layout through crafted input parameters that exceed the expected buffer boundaries, potentially leading to arbitrary code execution or system compromise. The issue is categorized under CWE-121 as a heap-based buffer overflow, which represents a well-known class of vulnerabilities that has been extensively documented in cybersecurity literature and forms part of the foundational knowledge for secure coding practices.
The technical exploitation of this vulnerability occurs when FFmpeg processes a specially crafted PNG file that contains malformed metadata or compressed data structures. During the decode_frame_common function execution, the application attempts to write data beyond the allocated buffer space, causing memory corruption that can be leveraged by attackers to overwrite adjacent memory locations. This out-of-bounds write behavior creates opportunities for attackers to manipulate program execution flow through techniques such as return-oriented programming or direct code injection. The vulnerability is particularly concerning because PNG format is widely supported across various applications and platforms, making it an attractive target for attackers seeking to exploit multimedia processing libraries. The heap-based nature of the overflow means that the memory corruption affects the application's heap memory management system, potentially leading to more sophisticated exploitation techniques that can bypass modern memory protection mechanisms.
The operational impact of CVE-2017-7863 extends beyond simple denial of service scenarios, as the vulnerability can be exploited to achieve remote code execution on systems running affected versions of FFmpeg. This risk is amplified by the widespread use of FFmpeg in multimedia applications, content management systems, and streaming platforms where users may unknowingly process malicious media files. The vulnerability affects not only direct FFmpeg usage but also applications that depend on FFmpeg for media processing, creating a broad attack surface that includes web applications, mobile platforms, and enterprise multimedia systems. Security researchers have classified this vulnerability as high-risk due to its exploitable nature and the prevalence of PNG file handling in modern software ecosystems. The potential for privilege escalation and system compromise makes this vulnerability particularly dangerous in environments where multimedia processing occurs without proper input sanitization or sandboxing measures. Organizations using FFmpeg in production environments must consider the risk of attackers leveraging this vulnerability through various attack vectors including web-based file uploads, automated processing pipelines, and content delivery networks.
Mitigation strategies for CVE-2017-7863 primarily focus on immediate software updates to versions released after February 4, 2017, which contain the necessary patches to address the heap-based buffer overflow. System administrators should prioritize patching all affected FFmpeg installations across their infrastructure, including servers, desktop applications, and embedded systems that process PNG files. Additionally, input validation measures should be implemented at the application level to sanitize PNG file inputs before they are processed by FFmpeg, reducing the attack surface even when using older versions. Network-based protections such as content filtering and sandboxed processing environments can provide additional layers of defense against exploitation attempts. Organizations should also consider implementing monitoring and detection mechanisms to identify potential exploitation attempts through unusual memory access patterns or process behavior. The vulnerability serves as a reminder of the importance of regular security updates and proper input validation in multimedia processing applications, aligning with ATT&CK technique T1059.007 for execution through command and scripting interpreter. Security teams should maintain awareness of similar vulnerabilities in multimedia libraries and implement comprehensive vulnerability management programs to address related issues across their software supply chain.