CVE-2018-9133 in ImageMagick
Summary
by MITRE
ImageMagick 7.0.7-26 Q16 has excessive iteration in the DecodeLabImage and EncodeLabImage functions (coders/tiff.c), which results in a hang (tens of minutes) with a tiny PoC file. Remote attackers could leverage this vulnerability to cause a denial of service via a crafted tiff file.
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Analysis
by VulDB Data Team • 02/24/2023
The vulnerability identified as CVE-2018-9133 affects ImageMagick version 7.0.7-26 Q16 and represents a critical denial of service flaw stemming from excessive iteration in the DecodeLabImage and EncodeLabImage functions within the TIFF coder component. This issue manifests when processing specially crafted TIFF files that trigger iterative processing loops, causing the application to hang for extended periods ranging from tens of minutes to hours. The vulnerability specifically resides in the coders/tiff.c file where the LAB color space handling functions fail to implement proper iteration limits or bounds checking mechanisms. Attackers can exploit this weakness remotely by delivering malicious TIFF files to systems running vulnerable ImageMagick versions, making it particularly dangerous in web environments where users might unknowingly trigger the vulnerable code path. The impact extends beyond simple resource exhaustion as the prolonged hanging behavior can effectively render the target system unresponsive to legitimate requests during the attack window.
The technical implementation of this vulnerability demonstrates a classic case of inadequate input validation and loop boundary checking within image processing libraries. When ImageMagick encounters a malformed TIFF file with specific LAB color space parameters, the DecodeLabImage and EncodeLabImage functions enter into iterative processing that lacks proper termination conditions. This flaw aligns with CWE-835, which addresses the issue of infinite loops or excessive iterations in software implementations. The vulnerability is particularly concerning because it requires minimal payload size to trigger the excessive iteration behavior, making it highly efficient for denial of service attacks. The iterative nature suggests that the code attempts to process color components in a manner that scales exponentially or linearly without proper safeguards against malformed input data. This represents a failure in defensive programming practices where input validation should occur before processing begins, and where iterative algorithms should include explicit iteration limits to prevent system resource exhaustion.
The operational impact of CVE-2018-9133 extends far beyond simple service disruption as it can be leveraged in various attack scenarios including distributed denial of service attacks and resource exhaustion campaigns. Systems that rely on ImageMagick for image processing, particularly web applications, content management systems, and file upload services, become vulnerable to sustained attacks that can consume significant CPU and memory resources. The extended hanging times make this vulnerability particularly effective for resource exhaustion attacks where multiple malicious files can be processed sequentially to maintain system unresponsiveness. Security professionals should note that this vulnerability affects not only direct web applications but also any system that processes untrusted image files through ImageMagick, including email servers, file sharing platforms, and automated image processing pipelines. The remote exploitation capability means that attackers do not need physical access to the target system and can leverage this vulnerability through network-based attacks, making it particularly dangerous in cloud environments where multiple services might be exposed to untrusted input.
Mitigation strategies for CVE-2018-9133 should focus on immediate patching of ImageMagick installations to versions that contain fixed implementations of the affected functions. Organizations should implement strict input validation and file type checking mechanisms before any image processing occurs, particularly in web applications that accept user uploads. The use of sandboxing techniques and resource limiting mechanisms can help contain the impact of such vulnerabilities by preventing excessive CPU or memory consumption. Network-level protections such as content filtering and file type restrictions should be implemented to prevent malicious TIFF files from reaching systems that process images. Security monitoring should include detection of unusual processing patterns that might indicate exploitation attempts, and system administrators should implement proper logging and alerting for extended processing times. Additionally, the vulnerability highlights the importance of implementing proper bounds checking and iteration limits in all image processing libraries, aligning with ATT&CK technique T1499.004 for resource exhaustion attacks. Organizations should also consider implementing automated vulnerability scanning and patch management processes to ensure timely remediation of similar issues in other image processing libraries and applications.