CVE-2018-7443 in ImageMagick
Summary
by MITRE
The ReadTIFFImage function in coders/tiff.c in ImageMagick 7.0.7-23 Q16 does not properly validate the amount of image data in a file, which allows remote attackers to cause a denial of service (memory allocation failure in the AcquireMagickMemory function in MagickCore/memory.c).
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Analysis
by VulDB Data Team • 02/10/2023
The vulnerability identified as CVE-2018-7443 resides within ImageMagick's TIFF image processing functionality, specifically in the ReadTIFFImage function located in coders/tiff.c. This flaw represents a classic case of insufficient input validation where the software fails to properly verify the integrity and size constraints of TIFF image data during parsing operations. The vulnerability affects ImageMagick version 7.0.7-23 Q16, making it particularly concerning given the widespread use of this image processing library across various platforms and applications. The issue manifests when the application encounters malformed TIFF files that contain misleading metadata regarding image dimensions or data size, leading to improper memory allocation behavior.
The technical exploitation of this vulnerability occurs through a memory allocation failure that originates from the AcquireMagickMemory function in MagickCore/memory.c. When the ReadTIFFImage function processes a maliciously crafted TIFF file, it incorrectly interprets the file's metadata to determine the amount of memory required for image data storage. This misinterpretation causes the application to attempt allocating excessive memory resources, often resulting in memory allocation failures that crash the application. The flaw stems from the absence of proper bounds checking and validation mechanisms that should verify whether the claimed image data size is reasonable given the actual file size and structure. This type of vulnerability falls under CWE-129, which addresses insufficient input validation, and more specifically aligns with CWE-704, concerning improper input validation during memory allocation operations.
The operational impact of CVE-2018-7443 extends beyond simple denial of service conditions, as it can be leveraged by remote attackers to disrupt services that depend on ImageMagick for image processing. Web applications, content management systems, and file processing services that utilize ImageMagick are particularly vulnerable when they accept user-uploaded TIFF files without proper sanitization. Attackers can craft malicious TIFF files that trigger the memory allocation failure, causing the target application to crash or become unresponsive, effectively creating a denial of service condition. This vulnerability is especially dangerous in environments where ImageMagick is used in automated processing pipelines or server-side image handling, as it can be exploited to exhaust system resources or cause cascading failures across dependent services. The ATT&CK framework categorizes this vulnerability under T1499.004, specifically targeting network denial of service through resource exhaustion.
Mitigation strategies for CVE-2018-7443 should focus on both immediate remediation and long-term architectural improvements. The most effective immediate solution involves upgrading to ImageMagick version 7.0.8-1 or later, where the vulnerability has been patched through enhanced input validation and proper bounds checking mechanisms. Organizations should implement comprehensive file validation procedures that include MIME type checking, size limitations, and format-specific validation before processing any user-uploaded files. Network-level protections such as rate limiting and input sanitization can help reduce the attack surface, while application-level safeguards including memory limits and resource monitoring should be implemented to prevent exploitation. Additionally, regular security assessments and vulnerability scanning should be conducted to identify similar issues in other image processing libraries and dependencies. The remediation process should also include proper error handling and logging mechanisms that can detect and alert on anomalous memory allocation patterns, enabling quicker incident response and forensic analysis.