CVE-2006-2440 in ImageMagick
Summary
by MITRE
Heap-based buffer overflow in the libMagick componet of ImageMagick 6.0.6.2 might allow attackers to execute arbitrary code via an image index array that triggers the overflow during filename glob expansion by the ExpandFilenames function.
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Analysis
by VulDB Data Team • 07/14/2019
The vulnerability described in CVE-2006-2440 represents a critical heap-based buffer overflow within the libMagick component of ImageMagick version 6.0.6.2. This flaw exists in the ExpandFilenames function which processes filename glob expansion operations, creating a dangerous condition where attacker-controlled input can corrupt heap memory. The vulnerability specifically manifests when processing image index arrays that undergo glob expansion, allowing malicious actors to manipulate memory layout and potentially execute arbitrary code. The heap overflow occurs due to insufficient bounds checking during the expansion process, where the system allocates memory based on attacker-supplied data without proper validation of array boundaries.
The technical implementation of this vulnerability stems from improper memory management within the image processing pipeline of ImageMagick. When the ExpandFilenames function encounters a glob pattern in an image index array, it attempts to expand the pattern and allocate heap memory for the resulting file list. However, the function fails to validate the size of the expanded array against the allocated buffer space, creating a condition where a carefully crafted input can exceed the buffer boundaries. This heap corruption can overwrite adjacent memory locations including function pointers, return addresses, or other critical control data structures. The vulnerability is particularly dangerous because it operates within the core image processing libraries that are widely used across various applications and systems, making exploitation possible through multiple attack vectors including web applications, email attachments, and file upload handlers.
The operational impact of this vulnerability extends far beyond simple code execution, as it provides attackers with a pathway to gain arbitrary code execution on systems running vulnerable versions of ImageMagick. The attack surface is broad since ImageMagick is integrated into numerous applications including web servers, content management systems, and image processing utilities. Successful exploitation can lead to complete system compromise, allowing attackers to install malware, establish persistence, or escalate privileges. The vulnerability is particularly concerning in web environments where users can upload images, as attackers can craft malicious image files that trigger the overflow when processed by vulnerable applications. This creates a significant risk for organizations that rely on image processing capabilities without proper input validation and sandboxing measures.
Mitigation strategies for CVE-2006-2440 must address both immediate remediation and long-term architectural improvements. The primary solution involves upgrading to a patched version of ImageMagick where the buffer overflow has been corrected through proper bounds checking and memory allocation validation. Organizations should also implement input validation measures that sanitize all image file inputs, particularly those that may contain glob patterns or special characters. Additional protective measures include deploying sandboxing mechanisms that isolate image processing operations, implementing strict file type validation, and using privilege separation techniques to limit the impact of potential exploitation. The vulnerability aligns with CWE-121, Heap-based Buffer Overflow, and represents a classic example of how improper memory management can create severe security implications. From an ATT&CK framework perspective, this vulnerability maps to T1059.007 Command and Scripting Interpreter: PowerShell and T1203 Exploitation for Client Execution, as it enables attackers to execute arbitrary code through legitimate system interfaces. Organizations should also consider implementing network segmentation and monitoring for suspicious file processing activities to detect potential exploitation attempts.