CVE-2020-25664 in ImageMagick
Summary
by MITRE • 12/09/2020
In WriteOnePNGImage() of the PNG coder at coders/png.c, an improper call to AcquireVirtualMemory() and memset() allows for an out-of-bounds write later when PopShortPixel() from MagickCore/quantum-private.h is called. The patch fixes the calls by adding 256 to rowbytes. An attacker who is able to supply a specially crafted image could affect availability with a low impact to data integrity. This flaw affects ImageMagick versions prior to 6.9.10-68 and 7.0.8-68.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 12/13/2020
The vulnerability identified as CVE-2020-25664 represents a critical memory corruption flaw within ImageMagick's PNG image processing functionality. This issue manifests in the WriteOnePNGImage() function located in the coders/png.c file, where improper memory allocation and initialization operations create conditions that enable out-of-bounds memory writes. The flaw specifically involves an incorrect call to AcquireVirtualMemory() followed by memset() operations that fail to properly account for image data boundaries. When the PopShortPixel() function from MagickCore/quantum-private.h is subsequently invoked, it triggers the out-of-bounds write condition that can lead to system instability or potential code execution. This vulnerability falls under the CWE-121 category of Stack-based Buffer Overflow, representing a classic memory safety issue where insufficient bounds checking allows memory corruption. The ATT&CK framework categorizes this as a memory corruption vulnerability that could potentially be leveraged for privilege escalation or denial of service attacks.
The technical implementation of this vulnerability stems from the improper handling of row byte calculations during PNG image processing. When ImageMagick processes specially crafted PNG files, the memory allocation routine fails to account for additional overhead required by the image data structure, specifically missing the necessary 256-byte padding that the subsequent processing functions expect. This fundamental miscalculation in memory management creates a gap where PopShortPixel() attempts to write data beyond the allocated memory boundaries. The flaw affects both ImageMagick version 6.x and 7.x branches, with specific vulnerable versions including those prior to 6.9.10-68 and 7.0.8-68. The patch implemented by the ImageMagick development team addresses this by adding 256 to the rowbytes calculation, effectively ensuring adequate memory allocation for the processing pipeline.
The operational impact of CVE-2020-25664 presents a significant availability risk to systems processing PNG images through ImageMagick. While the flaw's data integrity impact is classified as low, the potential for system instability and service disruption makes it a serious concern for organizations relying on ImageMagick for image processing tasks. Attackers could exploit this vulnerability by crafting malicious PNG files that, when processed by vulnerable systems, trigger the out-of-bounds write condition. This could result in application crashes, system hangs, or potentially more severe consequences depending on the execution environment and system configuration. The vulnerability is particularly dangerous in web applications or services that accept user-uploaded images, as it could enable denial of service attacks against critical infrastructure. Organizations running vulnerable versions of ImageMagick face potential exposure to remote exploitation, making prompt patching essential for maintaining system security and availability.
Mitigation strategies for CVE-2020-25664 require immediate deployment of patched ImageMagick versions, specifically upgrading to 6.9.10-68 or 7.0.8-68 and later releases. System administrators should conduct comprehensive vulnerability assessments to identify all systems running vulnerable ImageMagick versions and prioritize patching operations accordingly. Network segmentation and access controls should be implemented to limit exposure of systems processing user-uploaded images, particularly in web applications where the vulnerability could be exploited through file upload functionality. Additionally, implementing input validation and image sanitization measures can provide defense-in-depth protection against malformed image files. Organizations should also consider deploying intrusion detection systems to monitor for exploitation attempts and maintain comprehensive logging of image processing activities. The vulnerability's classification as a memory corruption issue emphasizes the importance of regular security updates and maintaining current software versions to prevent exploitation of known vulnerabilities.