CVE-2020-27772 in ImageMagick
Summary
by MITRE • 12/05/2020
A flaw was found in ImageMagick in coders/bmp.c. An attacker who submits a crafted file that is processed by ImageMagick could trigger undefined behavior in the form of values outside the range of type `unsigned int`. This would most likely lead to an impact to application availability, but could potentially cause other problems related to undefined behavior. This flaw affects ImageMagick versions prior to 7.0.9-0.
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Analysis
by VulDB Data Team • 12/12/2020
The vulnerability identified as CVE-2020-27772 represents a critical memory safety issue within ImageMagick's bitmap handling functionality. This flaw exists in the coders/bmp.c source file where improper input validation leads to undefined behavior during image processing operations. The vulnerability manifests when ImageMagick processes specially crafted bitmap files that contain malformed data structures, specifically triggering conditions that result in unsigned integer overflow scenarios.
The technical implementation of this vulnerability stems from inadequate bounds checking and type validation within the bitmap file parser. When ImageMagick encounters a maliciously constructed bmp file, the parsing logic fails to properly validate the size parameters and data offsets within the bitmap header structures. This allows attackers to manipulate memory access patterns that ultimately cause values to exceed the valid range of unsigned int data types, creating a condition known as integer overflow. The underlying CWE classification for this issue is CWE-191, which specifically addresses integer underflow and overflow conditions.
From an operational perspective, this vulnerability poses significant risks to applications that utilize ImageMagick for image processing, particularly those handling untrusted user uploads or third-party image files. The undefined behavior resulting from the overflow can manifest in various ways including application crashes, memory corruption, or potentially more severe consequences depending on the execution environment. While the primary impact is typically application availability through crashes and service disruption, the underlying memory corruption could potentially be exploited to achieve more sophisticated attack vectors such as code execution or privilege escalation in certain environments.
The vulnerability affects all ImageMagick versions prior to 7.0.9-0, making it particularly concerning for systems that have not received recent security updates. Organizations using ImageMagick for image processing in web applications, content management systems, or any environment where user-provided files are processed are at risk. The flaw demonstrates the importance of proper input validation and memory safety practices in image processing libraries that handle potentially malicious data from untrusted sources.
Security mitigations for CVE-2020-27772 primarily involve upgrading to ImageMagick version 7.0.9-0 or later, which contains the necessary patches to address the integer overflow conditions. Additionally, administrators should implement proper input validation at application layers, restrict file type processing, and consider using sandboxed environments for image processing operations. Network-level protections such as content filtering and file extension validation can provide additional defense-in-depth measures. The ATT&CK framework categorizes this vulnerability under T1203, which involves exploitation of software vulnerabilities in image processing applications, emphasizing the need for comprehensive security controls around multimedia processing components. Organizations should also consider implementing automated patch management systems to ensure timely deployment of security updates and reduce the window of exposure for such vulnerabilities.