CVE-2018-18024 in ImageMagick
Summary
by MITRE
In ImageMagick 7.0.8-13 Q16, there is an infinite loop in the ReadBMPImage function of the coders/bmp.c file. Remote attackers could leverage this vulnerability to cause a denial of service via a crafted bmp file.
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Analysis
by VulDB Data Team • 05/23/2023
The vulnerability identified as CVE-2018-18024 represents a critical denial of service flaw within ImageMagick version 7.0.8-13 Q16, specifically affecting the BMP image format processing functionality. This issue manifests as an infinite loop within the ReadBMPImage function located in the coders/bmp.c source file, creating a condition where the software enters an endless execution cycle when processing malformed BMP files. The flaw demonstrates significant security implications as it can be exploited remotely through crafted BMP files, potentially allowing attackers to consume excessive system resources and render services unavailable to legitimate users.
The technical root cause of this vulnerability stems from inadequate input validation and error handling within the BMP image parser implementation. When ImageMagick encounters a specially crafted BMP file containing malformed data structures or inconsistent header values, the ReadBMPImage function fails to properly terminate its processing loop, resulting in continuous resource consumption. This behavior aligns with CWE-835, which specifically addresses the issue of infinite loops in software implementations where loop termination conditions are not properly enforced. The vulnerability operates at the boundary between legitimate input processing and malformed data handling, where normal processing flow becomes disrupted by unexpected data patterns that cause the parser to cycle indefinitely.
From an operational impact perspective, this vulnerability creates substantial risks for systems that process BMP images through ImageMagick, particularly those exposed to untrusted input sources such as web applications, file upload handlers, or automated image processing pipelines. The infinite loop condition leads to complete denial of service as system resources including cpu cycles and memory become consumed without resolution, effectively making the affected service unavailable to legitimate users. Attackers can exploit this weakness by simply uploading or transmitting a maliciously crafted BMP file, requiring minimal technical expertise while achieving maximum disruption potential. This makes the vulnerability particularly dangerous in environments where ImageMagick is used as part of content management systems, image processing workflows, or any application that accepts user-provided image files without proper sanitization.
The exploitation of this vulnerability follows patterns consistent with ATT&CK technique T1499.001, which involves denial of service attacks through resource exhaustion. The attack surface extends across various deployment scenarios where ImageMagick is integrated, including web servers, file processing systems, and automated workflow engines. Organizations using ImageMagick for image handling and conversion are particularly vulnerable, as the flaw can be triggered through common file upload mechanisms, email attachments, or any process that involves BMP file parsing. The vulnerability's remote exploitability means that attackers need not have physical access to the target system, making it a significant threat vector for network-based attacks.
Mitigation strategies for CVE-2018-18024 should focus on immediate patching of ImageMagick installations to version 7.0.8-14 or later, which contains the necessary fixes for the infinite loop condition. Organizations should implement comprehensive input validation and sanitization measures for all image processing workflows, including MIME type checking, file size limits, and format-specific validation. Network-level protections such as rate limiting and file type restrictions can provide additional defense-in-depth measures. System administrators should monitor for unusual resource consumption patterns that might indicate exploitation attempts, and implement proper logging to track image processing activities. The fix implemented in the patched version addresses the core loop termination issue by adding proper bounds checking and error handling mechanisms to prevent the parser from entering infinite execution cycles when encountering malformed BMP data structures, thereby restoring normal service operation and preventing resource exhaustion attacks.