CVE-2020-21679 in GraphicsMagick
Summary
by MITRE • 08/22/2023
Buffer Overflow vulnerability in WritePCXImage function in pcx.c in GraphicsMagick 1.4 allows remote attackers to cause a denial of service via converting of crafted image file to pcx format.
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Analysis
by VulDB Data Team • 09/14/2023
The vulnerability identified as CVE-2020-21679 represents a critical buffer overflow condition within the GraphicsMagick image processing library, specifically within the WritePCXImage function located in the pcx.c source file. This flaw exists in GraphicsMagick version 1.4 and demonstrates a classic memory safety issue where insufficient input validation allows maliciously crafted image data to trigger unauthorized memory access patterns. The vulnerability manifests during the conversion process when GraphicsMagick attempts to serialize image data into PCX format, a widely used raster graphics file format. The buffer overflow occurs because the implementation fails to properly validate the size of input data against allocated buffer boundaries, creating a scenario where attacker-controlled data can overwrite adjacent memory regions.
The technical exploitation of this vulnerability requires an attacker to craft a malicious image file that, when processed by GraphicsMagick and converted to PCX format, triggers the buffer overflow condition. This attack vector represents a remote code execution risk, though the immediate impact is typically limited to denial of service rather than arbitrary code execution. The flaw falls under CWE-121, which categorizes buffer overflow conditions as a fundamental memory safety issue, and aligns with ATT&CK technique T1203, which covers legitimate program execution through process injection or manipulation of input processing pipelines. The vulnerability is particularly concerning because GraphicsMagick is widely deployed across various platforms and applications, including web services, content management systems, and image processing workflows that handle user-uploaded content.
The operational impact of CVE-2020-21679 extends beyond simple service disruption, as it can be leveraged in broader attack chains targeting web applications that utilize GraphicsMagick for image processing. When exploited, the vulnerability can cause application crashes, process termination, and system instability, effectively rendering the affected service unavailable to legitimate users. This makes it a valuable tool for attackers seeking to perform denial of service attacks against systems that rely on GraphicsMagick for image conversion services. The vulnerability affects not only individual applications but also entire infrastructure components that depend on GraphicsMagick's image processing capabilities, particularly in environments where user-generated content is processed and converted to various formats. Organizations utilizing GraphicsMagick in production environments should consider this vulnerability as part of their broader security posture assessment, as it can be combined with other techniques to create more sophisticated attack scenarios.
Mitigation strategies for this vulnerability should prioritize immediate patching of GraphicsMagick installations to version 1.4 or later, where the buffer overflow has been addressed through proper input validation and memory boundary checks. System administrators should implement robust input sanitization measures for all image processing workflows, particularly those involving user-uploaded content, by employing strict file format validation and size limitations. Network-level protections can include implementing content filtering mechanisms that detect and block suspicious image file patterns, while application-level defenses should incorporate proper error handling and memory management practices. Additionally, organizations should establish monitoring protocols to detect unusual application behavior or process termination patterns that may indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of regular security updates and the need for comprehensive input validation across all image processing components, particularly in environments where third-party libraries handle untrusted data inputs.