CVE-2017-6499 in ImageMagick
Summary
by MITRE
An issue was discovered in Magick++ in ImageMagick 6.9.7. A specially crafted file creating a nested exception could lead to a memory leak (thus, a DoS).
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Analysis
by VulDB Data Team • 09/04/2020
The vulnerability identified as CVE-2017-6499 represents a critical memory management flaw within the Magick++ component of ImageMagick version 6.9.7. This issue stems from improper exception handling mechanisms that fail to properly release allocated memory resources when processing malformed input files. The vulnerability manifests when a specially crafted file triggers a nested exception scenario, creating a cascade of memory allocations that are not adequately cleaned up during the exception handling process. This memory leak occurs because the underlying memory management system does not properly account for all allocated resources when exceptions are thrown in nested contexts, leading to gradual memory consumption that can eventually exhaust system resources.
The technical implementation of this vulnerability leverages the exception handling architecture within ImageMagick's Magick++ library to create a scenario where memory allocated during the processing of malicious input files remains unreleased. When the library encounters a malformed file that triggers nested exception conditions, the standard cleanup procedures fail to execute properly, resulting in memory fragments that accumulate over time. This behavior directly relates to CWE-401, which describes improper handling of memory allocation failures and resource leaks in software systems. The vulnerability operates at the intersection of memory management and exception handling, where the expected behavior of resource cleanup during exception propagation is disrupted, creating a persistent memory consumption pattern that degrades system performance and can lead to complete service unavailability.
From an operational impact perspective, this vulnerability creates a significant denial-of-service condition that can be exploited by remote attackers without authentication requirements. The memory leak behavior allows an attacker to repeatedly submit malicious files to a vulnerable system, causing progressive memory exhaustion and eventual system crash or service disruption. The vulnerability affects any system running ImageMagick 6.9.7 or earlier versions where Magick++ is utilized for image processing, including web applications, content management systems, and file processing services. The DoS condition can be particularly devastating in high-traffic environments where multiple concurrent requests are processed, as the memory leak accelerates and can quickly overwhelm system resources, potentially affecting other services running on the same host system.
The exploitation of CVE-2017-6499 aligns with ATT&CK technique T1499.001 which covers network denial of service attacks through resource exhaustion. Security professionals should implement immediate mitigations including updating to ImageMagick version 6.9.8 or later, which contains the patched exception handling logic that properly releases all allocated resources during nested exception scenarios. Additional protective measures include implementing resource limits on image processing services, deploying input validation mechanisms to filter suspicious file formats, and monitoring system memory usage for unusual patterns that might indicate exploitation attempts. Organizations should also consider implementing sandboxing or containerization for image processing components to limit the impact of potential exploitation and prevent the memory leak from affecting other system processes. The vulnerability demonstrates the critical importance of proper resource management in exception handling code and highlights the need for comprehensive testing of error conditions in security-sensitive applications.