CVE-2017-17879 in ImageMagick
Summary
by MITRE
In ImageMagick 7.0.7-16 Q16 x86_64 2017-12-21, there is a heap-based buffer over-read in ReadOneMNGImage in coders/png.c, related to length calculation and caused by an off-by-one error.
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Analysis
by VulDB Data Team • 01/19/2023
The vulnerability identified as CVE-2017-17879 represents a critical heap-based buffer over-read flaw within ImageMagick's handling of MNG (Multiple Network Graphics) image files. This issue manifests specifically in the ReadOneMNGImage function located within the coders/png.c source file, where improper length calculation leads to memory access violations that can potentially be exploited by malicious actors. The vulnerability affects ImageMagick versions up to 7.0.7-16, making it a significant concern for systems that process untrusted image content. The flaw occurs during the parsing of MNG format files, which are based on the PNG specification but extend it to support animation and other advanced features. When processing malformed MNG files, the application attempts to read memory locations beyond the allocated buffer boundaries, creating potential pathways for information disclosure or arbitrary code execution.
The technical root cause of this vulnerability stems from an off-by-one error in the length calculation logic within the PNG coder component. This type of error occurs when a program incorrectly handles boundary conditions during array or buffer operations, specifically when dealing with the size parameter used in memory allocation or access operations. The flaw exists in the calculation of data length during the parsing of MNG image sequences, where the software fails to properly account for the boundary conditions of the buffer being accessed. This misalignment between expected and actual buffer boundaries results in the program reading one byte beyond the allocated memory region, which can expose sensitive data from adjacent memory locations or cause application crashes. The vulnerability is classified as a heap-based buffer over-read, meaning that the buffer in question resides in the heap memory segment rather than on the stack, making it particularly challenging to detect and exploit consistently.
The operational impact of this vulnerability extends beyond simple application crashes, as it can potentially be leveraged for more sophisticated attacks within environments where ImageMagick is used for processing untrusted image content. Systems that automatically process image uploads, such as web applications, content management systems, or image processing pipelines, become vulnerable to remote code execution or information disclosure attacks when they utilize affected versions of ImageMagick. The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and specifically relates to improper input validation during file format parsing operations. Attackers could craft malicious MNG files that trigger the buffer over-read condition, potentially leading to the exposure of memory contents including stack canaries, heap metadata, or other sensitive information that could aid in further exploitation. The risk is particularly elevated in server environments where ImageMagick is used for automated image processing without proper input sanitization.
Mitigation strategies for CVE-2017-17879 should prioritize immediate version updates to ImageMagick 7.0.7-17 or later, which contain the necessary patches to address the buffer over-read condition. Organizations should also implement strict input validation and sanitization measures, particularly when processing image files from untrusted sources, including implementing file format validation, size limits, and content inspection before image processing. The use of sandboxing techniques and restricted execution environments can help contain potential exploitation attempts by limiting the impact of any successful attacks. Additionally, implementing network segmentation and access controls can reduce the attack surface by limiting exposure to systems that process image content. From a defensive perspective, monitoring for anomalous file processing patterns and implementing automated vulnerability scanning can help identify systems running affected versions of ImageMagick. This vulnerability demonstrates the importance of proper memory management and input validation in multimedia processing libraries, and aligns with ATT&CK technique T1203, which covers obfuscated files or information, as attackers may attempt to hide malicious payloads within crafted image files designed to exploit such buffer over-read conditions.