CVE-2017-6498 in ImageMagick
Summary
by MITRE
An issue was discovered in ImageMagick 6.9.7. Incorrect TGA files could trigger assertion failures, thus leading to DoS.
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Analysis
by VulDB Data Team • 09/04/2020
The vulnerability identified as CVE-2017-6498 represents a critical denial of service flaw within ImageMagick version 6.9.7 and earlier. This issue stems from improper handling of malformed TGA (Targa) image files during the parsing process, which can cause the application to crash or become unresponsive when processing specifically crafted malicious files. The flaw manifests as assertion failures that occur during the validation of TGA file headers and metadata structures, ultimately leading to system instability and service disruption. This vulnerability affects a wide range of applications that rely on ImageMagick for image processing, including web applications, content management systems, and digital asset management platforms that accept user-uploaded images.
The technical root cause of this vulnerability lies in the insufficient input validation mechanisms within ImageMagick's TGA file parser. When processing TGA files, the software fails to properly validate the file format structure and header fields, particularly concerning the image type field and color map specifications. The assertion failures occur when the parser encounters unexpected values or malformed data within these fields, causing the program to terminate abruptly rather than gracefully handling the error condition. This behavior aligns with CWE-691, which classifies inadequate input validation as a significant security weakness, and demonstrates how improper error handling can be exploited to cause denial of service conditions. The vulnerability operates at the application layer and can be triggered through various attack vectors including web uploads, file processing pipelines, and automated image conversion services.
The operational impact of CVE-2017-6498 extends beyond simple service disruption, as it can be exploited in multiple contexts that compromise system availability and reliability. In web environments, malicious users can upload specially crafted TGA files to trigger crashes in image processing pipelines, potentially affecting multiple concurrent users or system resources. This vulnerability can be particularly dangerous in cloud environments or shared hosting platforms where a single compromised service could impact multiple tenants. The DoS condition affects not only the immediate image processing functionality but can also cascade into broader system stability issues, especially when ImageMagick is integrated into larger application frameworks or used as a backend service for content delivery networks. The vulnerability is classified under the ATT&CK technique T1499.004 for Network Denial of Service, demonstrating how image processing libraries can become attack vectors for availability compromise.
Mitigation strategies for this vulnerability require immediate patching of ImageMagick installations to version 6.9.8-0 or later, which contains the necessary fixes for TGA file parsing. Organizations should implement comprehensive input validation measures that include file type detection, size limitations, and format verification before processing any image files. Network-level protections such as file extension filtering, content type validation, and sandboxed processing environments can provide additional defense-in-depth measures. Security teams should also consider implementing automated monitoring for unusual processing patterns that might indicate exploitation attempts, along with regular vulnerability assessments of all image processing components within their infrastructure. The fix addresses the underlying assertion failure by implementing proper bounds checking and error recovery mechanisms, ensuring that malformed TGA files do not cause application termination. Additionally, organizations should review their image processing workflows to ensure that all user-uploaded content is properly sanitized and validated before being processed by ImageMagick or similar libraries, preventing potential exploitation through indirect attack vectors.