CVE-2016-4563 in ImageMagick
Summary
by MITRE
The TraceStrokePolygon function in MagickCore/draw.c in ImageMagick before 6.9.4-0 and 7.x before 7.0.1-2 mishandles the relationship between the BezierQuantum value and certain strokes data, which allows remote attackers to cause a denial of service (buffer overflow and application crash) or possibly have unspecified other impact via a crafted file.
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Analysis
by VulDB Data Team • 08/22/2022
The vulnerability identified as CVE-2016-4563 represents a critical buffer overflow condition within ImageMagick's graphics processing library, specifically affecting the TraceStrokePolygon function located in MagickCore/draw.c. This flaw exists in versions prior to 6.9.4-0 for the 6.x series and 7.0.1-2 for the 7.x series, making it a widespread issue affecting numerous systems that rely on ImageMagick for image processing operations. The vulnerability stems from improper handling of the relationship between BezierQuantum value and strokes data, creating a scenario where maliciously crafted image files can trigger exploitable conditions during image rendering or processing.
The technical implementation of this vulnerability occurs when ImageMagick processes image files containing specially constructed stroke data that manipulates the BezierQuantum parameter in a manner that exceeds allocated buffer boundaries. The TraceStrokePolygon function fails to properly validate or constrain the relationship between the quantum value and the stroke data structure, leading to memory corruption when the application attempts to render or manipulate these malformed graphics elements. This improper boundary checking creates opportunities for attackers to craft image files that, when processed by vulnerable ImageMagick implementations, will cause buffer overflows that result in application crashes or potentially more severe consequences depending on the execution environment and memory layout.
The operational impact of CVE-2016-4563 extends beyond simple denial of service to potentially enable more sophisticated attacks depending on the deployment context. Remote attackers can leverage this vulnerability to cause application crashes through carefully constructed image files, effectively creating a denial of service condition that can impact web services, content management systems, and other applications that utilize ImageMagick for image handling. The unspecified other impacts mentioned in the vulnerability description suggest potential for more serious consequences including arbitrary code execution, particularly in environments where the affected applications run with elevated privileges or where memory corruption could be exploited through techniques such as return-oriented programming or other exploit mitigation bypasses. This vulnerability aligns with CWE-121, heap-based buffer overflow, and represents a classic example of improper input validation in graphics processing libraries.
Mitigation strategies for CVE-2016-4563 primarily focus on immediate version upgrades to patched releases of ImageMagick, specifically versions 6.9.4-0 or later for the 6.x series and 7.0.1-2 or later for the 7.x series. Organizations should implement comprehensive patch management procedures to ensure all systems utilizing ImageMagick are updated promptly, particularly web applications and services that process user-uploaded images. Additional protective measures include implementing strict file validation and sanitization processes that verify image file integrity before processing, employing sandboxing techniques for image processing operations, and configuring applications to use restricted execution environments that limit the potential impact of buffer overflow conditions. Network-based mitigations such as content filtering and web application firewalls can provide additional layers of protection by blocking suspicious image file uploads, while security monitoring should be implemented to detect potential exploitation attempts through unusual application behavior or crash patterns. The vulnerability demonstrates the importance of robust input validation in graphics libraries and aligns with ATT&CK technique T1203, Exploitation for Client Execution, when considering the potential for remote code execution in vulnerable configurations.