CVE-2017-7606 in ImageMagick
Summary
by MITRE
coders/rle.c in ImageMagick 7.0.5-4 has an "outside the range of representable values of type unsigned char" undefined behavior issue, which might allow remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact via a crafted image.
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Analysis
by VulDB Data Team • 10/13/2019
The vulnerability identified as CVE-2017-7606 resides within the ImageMagick image processing library, specifically in the coders/rle.c file version 7.0.5-4. This issue represents a critical undefined behavior flaw that occurs during the processing of Run-Length Encoded image files, which are commonly used in various graphics applications and web environments. The vulnerability manifests when the application encounters malformed image data that triggers memory access patterns outside the bounds of the unsigned char data type, creating a scenario where the program's behavior becomes unpredictable and potentially exploitable.
The technical flaw stems from improper input validation and boundary checking within the RLE decoder implementation. When processing crafted image files, the code fails to properly validate the range of values being read from the image data stream, leading to operations that attempt to store values outside the representable range of unsigned char data type, which is typically 0-255. This undefined behavior can result in memory corruption, stack overflow conditions, or other low-level system instabilities that manifest as application crashes or unexpected termination. The vulnerability is particularly concerning because it operates at the core image processing layer, where it can be triggered by simply opening or processing a maliciously crafted image file.
From an operational perspective, this vulnerability creates significant risk for systems that rely on ImageMagick for image processing tasks, including web servers, content management systems, and digital asset management platforms. Remote attackers can exploit this flaw by uploading or otherwise presenting a specially crafted RLE image file to any system running vulnerable ImageMagick versions, potentially leading to denial of service attacks that render the target application or system unusable. The impact extends beyond simple crashes as the undefined behavior could theoretically be leveraged for more sophisticated exploits depending on the execution environment and memory layout, making this a particularly dangerous vulnerability in web-facing applications where arbitrary image uploads are permitted.
The vulnerability maps to CWE-129 in the Common Weakness Enumeration catalog, which specifically addresses "Improper Validation of Array Index" and related issues involving out-of-bounds memory access. Additionally, this flaw aligns with ATT&CK technique T1203 - Exploitation for Client Execution, as it enables remote code execution or service disruption through crafted image files. Organizations should implement immediate mitigations including updating to patched versions of ImageMagick, implementing strict image file validation and sanitization processes, and configuring web applications to restrict image upload capabilities where possible. Network-level protections such as intrusion detection systems that monitor for suspicious image file patterns and application firewalls that can block known malicious file types should also be deployed to reduce the attack surface and prevent exploitation of this vulnerability in production environments.