CVE-2017-12673 in ImageMagick
Summary
by MITRE
In ImageMagick 7.0.6-3, a memory leak vulnerability was found in the function ReadOneMNGImage in coders/png.c, which allows attackers to cause a denial of service.
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Analysis
by VulDB Data Team • 12/15/2022
The vulnerability identified as CVE-2017-12673 represents a critical memory leak flaw within ImageMagick's handling of MNG (Multiple Network Graphics) image files. This issue specifically manifests in the ReadOneMNGImage function located within the coders/png.c source file, where improper memory management leads to resource exhaustion. The vulnerability affects ImageMagick versions up to and including 7.0.6-3, making it a significant concern for systems that process untrusted image content. The flaw operates by allocating memory for MNG image processing but failing to properly release this memory when encountering certain malformed input structures, creating a persistent memory consumption pattern that can be exploited by malicious actors.
From a technical perspective, the memory leak occurs during the parsing and rendering of MNG format images which are based on the PNG specification but extended with additional animation capabilities. When ImageMagick encounters a specially crafted MNG file with malformed or excessive metadata, the ReadOneMNGImage function initiates memory allocation for various image components including frame buffers, color tables, and animation control structures. However, the cleanup routines fail to properly deallocate these resources when the parsing encounters specific error conditions or when the image structure exceeds normal processing parameters. This results in a gradual accumulation of memory usage that can eventually exhaust available system resources, particularly affecting applications that process multiple image files or those running in memory-constrained environments.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it can severely compromise system stability and availability. Attackers can exploit this flaw by submitting maliciously crafted MNG files to applications that utilize ImageMagick for image processing, leading to progressive memory exhaustion that may cause application crashes, system slowdowns, or complete system instability. This vulnerability is particularly dangerous in web applications, content management systems, or any environment where users can upload or process external image content. The memory leak can be amplified through repeated exploitation attempts, potentially allowing attackers to maintain persistent resource exhaustion conditions that are difficult to detect and remediate.
Security practitioners should implement multiple layers of mitigation to address this vulnerability effectively. Immediate remediation involves upgrading to ImageMagick version 7.0.6-4 or later, which contains the necessary patches to properly handle memory allocation and deallocation during MNG image processing. Additionally, administrators should implement input validation and sanitization measures that filter or reject MNG files before they reach the ImageMagick processing pipeline. Network-level controls such as rate limiting and file type restrictions can help prevent exploitation attempts, while monitoring systems should be configured to detect unusual memory consumption patterns that may indicate exploitation activity. Organizations should also consider implementing sandboxing techniques and resource limits for image processing applications to contain the impact of potential exploitation attempts. This vulnerability aligns with CWE-401, which describes improper handling of memory allocation failures, and represents a classic example of how insufficient resource management can lead to denial of service conditions. The attack surface for this vulnerability can be mapped to ATT&CK technique T1499.004, which involves network denial of service attacks through resource exhaustion, making it a critical consideration for enterprise security posture assessments and vulnerability management programs.