CVE-2016-5687 in ImageMagick
Summary
by MITRE
The VerticalFilter function in the DDS coder in ImageMagick before 6.9.4-3 and 7.x before 7.0.1-4 allows remote attackers to have unspecified impact via a crafted DDS file, which triggers an out-of-bounds read.
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Analysis
by VulDB Data Team • 06/25/2019
The vulnerability identified as CVE-2016-5687 represents a critical out-of-bounds read flaw within ImageMagick's DDS (DirectDraw Surface) file processing functionality. This vulnerability affects versions prior to 6.9.4-3 and 7.x prior to 7.0.1-4, where the VerticalFilter function in the DDS coder fails to properly validate input data from crafted DDS files. The flaw stems from insufficient bounds checking during the decoding process, allowing attackers to manipulate file structures in ways that cause the application to read memory beyond allocated buffers. This type of vulnerability falls under the CWE-125 weakness category, which specifically addresses out-of-bounds read conditions that can lead to information disclosure, application crashes, or potentially code execution depending on memory layout.
The technical exploitation of this vulnerability occurs when ImageMagick processes a maliciously crafted DDS file that contains malformed data structures. During the VerticalFilter function execution, the application attempts to read data from memory locations that were not properly validated against the actual file boundaries. This creates a scenario where arbitrary memory content can be accessed and potentially exposed to the attacker. The vulnerability operates at the file format parsing layer, making it particularly dangerous as it can be triggered through any application that utilizes ImageMagick for image processing, including web applications, content management systems, and file processing services. The out-of-bounds read condition can result in information leakage that may reveal sensitive data from memory, potentially including cryptographic keys, user credentials, or application state information.
The operational impact of CVE-2016-5687 extends beyond simple information disclosure, as it represents a potential vector for more severe attacks within the ATT&CK framework's initial access and execution phases. Remote attackers can leverage this vulnerability through web applications that accept image uploads, enabling them to perform reconnaissance activities or potentially escalate privileges if the application runs with elevated permissions. The vulnerability's exploitation can lead to application instability and denial of service conditions, while the information disclosure aspect may provide attackers with insights into system memory structures that could be used to craft more sophisticated attacks. Organizations using ImageMagick in web-facing applications are particularly at risk, as the vulnerability can be exploited through simple file uploads without requiring user interaction or additional authentication.
Mitigation strategies for CVE-2016-5687 primarily involve upgrading to patched versions of ImageMagick where the DDS coder has been updated to properly validate input data and implement bounds checking. System administrators should also consider implementing file type validation and sanitization measures at the application level, ensuring that only properly formatted image files are processed by ImageMagick components. Network-level defenses such as web application firewalls can help detect and block suspicious file uploads that might contain malicious DDS structures. Additionally, organizations should implement principle of least privilege for applications that process images, ensuring that ImageMagick processes run with minimal necessary permissions to reduce potential impact if exploitation occurs. The vulnerability highlights the importance of proper input validation and bounds checking in file format parsers, aligning with security best practices outlined in the OWASP Top Ten and NIST cybersecurity guidelines for preventing buffer overflow and memory corruption vulnerabilities.