CVE-2016-6491 in ImageMagick
Summary
by MITRE
Buffer overflow in the Get8BIMProperty function in MagickCore/property.c in ImageMagick before 6.9.5-4 and 7.x before 7.0.2-6 allows remote attackers to cause a denial of service (out-of-bounds read, memory leak, and crash) via a crafted image.
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Analysis
by VulDB Data Team • 09/09/2022
The vulnerability identified as CVE-2016-6491 represents a critical buffer overflow flaw within ImageMagick's image processing library, specifically affecting the Get8BIMProperty function in MagickCore/property.c. This issue impacts both the 6.x series prior to version 6.9.5-4 and the 7.x series prior to version 7.0.2-6, creating a widespread security concern for systems relying on ImageMagick for image handling operations. The flaw manifests as a buffer overflow condition that can be exploited through maliciously crafted image files, potentially leading to system instability and service disruption.
The technical implementation of this vulnerability stems from inadequate input validation within the Get8BIMProperty function which processes 8BIM (Adobe Photoshop) properties embedded in image files. When processing specially crafted images containing malformed 8BIM metadata, the function fails to properly bounds-check array accesses, allowing attackers to read beyond allocated memory boundaries. This out-of-bounds read behavior can trigger memory corruption, leading to unpredictable program behavior including crashes, memory leaks, and potential exploitation for more severe attacks. The vulnerability operates at the core level of ImageMagick's image processing pipeline, making it particularly dangerous as it can be triggered during routine image loading operations.
From an operational impact perspective, this vulnerability creates significant risk for web applications and services that utilize ImageMagick for image processing, particularly those handling user-uploaded content. Attackers can leverage this flaw to cause denial of service conditions by submitting malicious images that trigger crashes in image processing applications. The memory leak aspect compounds the issue by gradually consuming system resources, potentially leading to system instability or complete service exhaustion. Organizations using ImageMagick in production environments face potential downtime and resource exhaustion risks, especially in high-volume scenarios where automated image processing is common.
The mitigation strategy for CVE-2016-6491 requires immediate patching of affected ImageMagick installations to versions 6.9.5-4 or 7.0.2-6, which contain the necessary code modifications to prevent the buffer overflow condition. Additionally, implementing proper input validation and sanitization measures at application layers can provide defense-in-depth protection, ensuring that even if the underlying library is not patched, malicious inputs are rejected before reaching the vulnerable code paths. Organizations should also consider implementing image processing sandboxing techniques and limiting file size and format restrictions for user uploads. This vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and maps to ATT&CK technique T1499.001 for denial of service attacks. Security monitoring should focus on detecting abnormal memory usage patterns and unexpected process crashes in image processing services, while network-based intrusion detection systems should be configured to identify suspicious image file characteristics that may indicate exploitation attempts.