CVE-2017-12936 in GraphicsMagick
Summary
by MITRE
The ReadWMFImage function in coders/wmf.c in GraphicsMagick 1.3.26 has a use-after-free issue for data associated with exception reporting.
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Analysis
by VulDB Data Team • 12/16/2022
The vulnerability identified as CVE-2017-12936 resides within the GraphicsMagick image processing library, specifically in the ReadWMFImage function located in the coders/wmf.c file. This issue manifests as a use-after-free condition that occurs during the processing of Windows Metafile (WMF) image formats, representing a critical memory safety flaw that can be exploited by malicious actors. The vulnerability is particularly concerning because GraphicsMagick is widely used in web applications, content management systems, and image processing pipelines where it handles user-uploaded files. When the ReadWMFImage function processes malformed WMF files, it attempts to free memory resources that are subsequently accessed, creating opportunities for arbitrary code execution or system compromise.
The technical root cause of this vulnerability stems from improper memory management within the exception handling mechanism of the WMF image reader. During normal operation, the function allocates memory for exception data structures and processes WMF image data. However, when certain error conditions are encountered, the code frees memory associated with exception reporting while still maintaining references to that freed memory. This creates a scenario where subsequent operations attempt to access already freed memory locations, leading to unpredictable behavior including crashes, data corruption, or potential exploitation. The flaw is classified as a CWE-416 Use After Free vulnerability, which is a well-documented category of memory safety issues that frequently leads to remote code execution in image processing libraries.
The operational impact of CVE-2017-12936 extends beyond simple denial of service scenarios, as it can enable attackers to execute arbitrary code on systems running vulnerable versions of GraphicsMagick. This vulnerability is particularly dangerous in web environments where users can upload images, as it allows for remote code execution through crafted WMF files. The attack vector typically involves an attacker uploading a malicious WMF file that, when processed by GraphicsMagick, triggers the use-after-free condition. This could lead to complete system compromise, data exfiltration, or as a stepping stone for further attacks in a network environment. The vulnerability affects all versions of GraphicsMagick prior to 1.3.27, making it a widespread concern for organizations using older versions of the library.
Mitigation strategies for this vulnerability primarily focus on immediate patching and updating to GraphicsMagick version 1.3.27 or later, which contains the necessary memory management fixes. Organizations should also implement defensive measures such as input validation and file type checking to prevent processing of untrusted WMF files, particularly in web applications. Additional security controls include implementing sandboxing techniques for image processing operations, deploying web application firewalls to filter malicious uploads, and conducting regular security assessments of image processing pipelines. From an ATT&CK framework perspective, this vulnerability maps to T1059 Command and Scripting Interpreter and T1203 Exploitation for Client Execution, as it enables attackers to execute arbitrary commands through the compromised image processing system. The vulnerability also aligns with defensive techniques such as T1562 Impair Defenses and T1070 Indicator Removal on Host, as exploitation may involve attempts to cover tracks or disable security measures.