CVE-2017-11524 in ImageMagick
Summary
by MITRE
The WriteBlob function in MagickCore/blob.c in ImageMagick before 6.9.8-10 and 7.x before 7.6.0-0 allows remote attackers to cause a denial of service (assertion failure and application exit) via a crafted file.
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Analysis
by VulDB Data Team • 12/13/2022
The vulnerability identified as CVE-2017-11524 represents a critical denial of service flaw within ImageMagick's MagickCore library, specifically affecting the WriteBlob function in the blob.c file. This issue impacts both the legacy 6.x series and the newer 7.x series of ImageMagick, with versions prior to 6.9.8-10 and 7.6.0-0 respectively being vulnerable. The flaw manifests when the software processes crafted malicious files, leading to an assertion failure that causes the application to terminate unexpectedly. This type of vulnerability falls under the category of software robustness issues and can be classified as a CWE-665 Improper Initialization, as the function fails to properly validate input data before processing.
The technical exploitation of this vulnerability occurs when an attacker crafts a specially formatted file that triggers an assertion check within the WriteBlob function. The assertion failure represents a fundamental breakdown in the software's error handling mechanisms, where the system encounters an unexpected condition that violates its internal assumptions. This condition causes the application to abruptly terminate rather than gracefully handling the malformed input. The vulnerability operates at the core level of the image processing pipeline, making it particularly dangerous as it can be triggered during routine file operations, potentially affecting web applications, content management systems, or any software that relies on ImageMagick for image handling.
From an operational perspective, this vulnerability creates significant risk for organizations that depend on ImageMagick for image processing tasks. The denial of service impact means that legitimate users may experience service interruptions when the application crashes, potentially allowing attackers to disrupt services or cause availability issues. The vulnerability is particularly concerning in web environments where users can upload images, as attackers can craft malicious files that will cause the application to crash whenever it attempts to process these inputs. This makes it an attractive vector for attackers seeking to perform service disruption attacks against systems that utilize ImageMagick for image manipulation.
The impact of this vulnerability extends beyond simple service disruption, as it can be leveraged as part of broader attack strategies within the MITRE ATT&CK framework. Specifically, it relates to the T1499.004 technique for Network Denial of Service, where attackers can exploit software flaws to cause system unavailability. Organizations implementing ImageMagick in their infrastructure should consider this vulnerability as part of their overall security posture assessment, particularly in environments where automated image processing occurs. The vulnerability demonstrates the importance of proper input validation and error handling in security-critical applications, as it highlights how a single assertion failure can compromise system availability.
Mitigation strategies for CVE-2017-11524 primarily involve updating to patched versions of ImageMagick, specifically versions 6.9.8-10 or later for the 6.x series and 7.6.0-0 or later for the 7.x series. Organizations should also implement input validation measures, such as file type checking and size limitations, to reduce the attack surface. Additionally, deploying application firewalls or web application firewalls that can detect and block suspicious file uploads can provide an additional layer of protection. The vulnerability underscores the importance of maintaining up-to-date software components and implementing robust error handling mechanisms that prevent assertion failures from causing application termination. Security teams should also consider implementing monitoring and alerting for application crashes or unexpected terminations that could indicate exploitation attempts.