CVE-2017-18273 in ImageMagick
Summary
by MITRE
In ImageMagick 7.0.7-16 Q16 x86_64 2017-12-22, an infinite loop vulnerability was found in the function ReadTXTImage in coders/txt.c, which allows attackers to cause a denial of service (CPU exhaustion) via a crafted image file that is mishandled in a GetImageIndexInList call.
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Analysis
by VulDB Data Team • 08/19/2024
The vulnerability CVE-2017-18273 represents a critical denial of service flaw within ImageMagick's text file handling mechanism, specifically affecting version 7.0.7-16 Q16 x86_64 released on December 22, 2017. This issue resides in the ReadTXTImage function located within the coders/txt.c source file, demonstrating how seemingly benign file processing operations can be exploited to create significant system instability. The flaw manifests when ImageMagick encounters a specially crafted image file that triggers an infinite loop during the GetImageIndexInList call, effectively consuming excessive CPU resources and rendering the system unresponsive to legitimate requests.
The technical implementation of this vulnerability stems from inadequate input validation and error handling within the text file parser component of ImageMagick. When processing malformed text-based image files, the ReadTXTImage function fails to properly terminate loop iterations that should gracefully handle malformed data structures. This condition creates a scenario where the application enters an infinite loop, continuously executing the same code path without making meaningful progress toward image processing completion. The GetImageIndexInList call becomes trapped in repetitive execution patterns, causing sustained high CPU utilization that can exhaust system resources and prevent other processes from executing effectively.
From an operational perspective, this vulnerability presents a significant risk to systems that process untrusted image files through ImageMagick, particularly those exposed to web applications, file upload services, or automated processing pipelines. Attackers can exploit this flaw by crafting malicious text files that appear legitimate to trigger the vulnerable code path, making it particularly dangerous in environments where users can upload arbitrary files. The denial of service impact extends beyond simple resource exhaustion, as prolonged CPU consumption can lead to system instability, application crashes, and potentially cascading failures in dependent services that rely on ImageMagick for image processing tasks.
Security practitioners should consider this vulnerability in the context of the CWE-835 weakness category, which specifically addresses infinite loops or iterations without proper termination conditions. The ATT&CK framework's privilege escalation and denial of service techniques may be applicable when attackers leverage this flaw to exhaust system resources or gain unauthorized access to processing capabilities. Organizations utilizing ImageMagick should implement immediate mitigations including updating to patched versions, implementing input validation controls, and deploying sandboxing mechanisms to isolate image processing operations. Additionally, network-based detection measures should monitor for unusual CPU utilization patterns that may indicate exploitation attempts, while access controls should limit file upload capabilities to trusted sources only.