CVE-2018-16645 in ImageMagick
Summary
by MITRE
There is an excessive memory allocation issue in the functions ReadBMPImage of coders/bmp.c and ReadDIBImage of coders/dib.c in ImageMagick 7.0.8-11, which allows remote attackers to cause a denial of service via a crafted image file.
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Analysis
by VulDB Data Team • 05/07/2023
The vulnerability CVE-2018-16645 represents a critical memory allocation flaw within ImageMagick's bitmap handling mechanisms, specifically affecting the ReadBMPImage and ReadDIBImage functions in the coders/bmp.c and coders/dib.c source files. This issue manifests as an excessive memory allocation pattern that occurs when processing malformed image files, creating a potential denial of service vector for remote attackers. The flaw exists in ImageMagick version 7.0.8-11, making it a significant concern for systems that process untrusted image content through this software library. The vulnerability stems from insufficient input validation and memory management controls during the parsing of bitmap and device-independent bitmap image formats, which are commonly used across various digital platforms and applications.
The technical exploitation of this vulnerability involves crafting a malicious image file that triggers the excessive memory allocation behavior when ImageMagick attempts to parse the file structure. When the ReadBMPImage or ReadDIBImage functions encounter specially constructed data within the image headers or metadata, they allocate memory resources in an uncontrolled manner that grows beyond normal operational limits. This excessive allocation pattern typically occurs due to improper bounds checking and size validation of image dimensions, color depth specifications, or compressed data segments. The flaw can be categorized under CWE-772, which addresses missing release of memory after effective lifetime, and specifically relates to improper handling of resource allocation in image processing libraries. Attackers can leverage this weakness by uploading or transmitting crafted image files to systems running vulnerable ImageMagick versions, causing the target application to consume excessive memory resources until system performance degrades or crashes occur.
The operational impact of CVE-2018-16645 extends beyond simple denial of service conditions, as it can severely disrupt services that rely on ImageMagick for image processing operations. Systems commonly affected include web applications, content management systems, image hosting platforms, and any software that accepts user-uploaded images and processes them through ImageMagick. The vulnerability can be exploited across multiple attack vectors including web application uploads, email attachments, and file sharing services where image files are processed automatically. When exploited successfully, the excessive memory allocation causes system resource exhaustion, leading to application crashes, service unavailability, and potential system instability. The impact is particularly severe in environments where multiple concurrent image processing operations occur, as the memory consumption can escalate rapidly and affect overall system performance. According to ATT&CK framework, this vulnerability maps to T1499.004 which covers "Resource Hijacking: Unnecessary Resource Exhaustion" and represents a classic example of how image processing libraries can become attack vectors for resource exhaustion attacks.
Mitigation strategies for CVE-2018-16645 require immediate patching of affected ImageMagick installations to version 7.0.8-12 or later, which contains the necessary fixes for the memory allocation issues in the bitmap handling functions. Organizations should implement comprehensive input validation and sanitization measures for all image uploads, including size limits, format restrictions, and automated malware scanning. Network-based defenses should include monitoring for unusual memory consumption patterns and implementing rate limiting for image processing operations. Additionally, system administrators should consider deploying ImageMagick within restricted execution environments or containerized deployments that can limit memory consumption and prevent complete system compromise. Regular security assessments and vulnerability scanning should be conducted to identify other potential memory allocation issues within image processing pipelines, as similar patterns may exist in other image handling libraries. The remediation process should also include updating all applications and services that depend on ImageMagick to ensure consistent protection against this and related vulnerabilities, while maintaining proper logging and monitoring to detect potential exploitation attempts.