CVE-2017-11637 in GraphicsMagick
Summary
by MITRE
GraphicsMagick 1.3.26 has a NULL pointer dereference in the WritePCLImage() function in coders/pcl.c during writes of monochrome images.
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Analysis
by VulDB Data Team • 12/14/2022
The vulnerability identified as CVE-2017-11637 represents a critical null pointer dereference flaw within GraphicsMagick version 1.3.26 that specifically affects the WritePCLImage() function located in the coders/pcl.c file. This issue manifests during the processing of monochrome image writes, creating a potential avenue for denial of service attacks and system instability. The flaw occurs when the application attempts to dereference a null pointer while handling PCL (Printer Command Language) image format output, particularly when dealing with monochrome image data structures. The vulnerability demonstrates characteristics consistent with CWE-476 which specifically addresses null pointer dereference conditions that can lead to application crashes or unexpected behavior.
The technical implementation of this vulnerability stems from inadequate input validation and error handling within the image processing pipeline. When GraphicsMagick processes monochrome images for PCL output, the WritePCLImage() function fails to properly validate pointer references before attempting to access memory locations. This failure results in a segmentation fault or access violation when the application tries to execute operations on a null pointer, effectively causing the application to terminate unexpectedly. The flaw is particularly concerning because it can be triggered through normal image processing workflows without requiring special privileges or complex exploitation techniques.
From an operational impact perspective, this vulnerability creates significant risks for systems that rely on GraphicsMagick for image processing tasks, particularly in server environments or applications that handle user-uploaded content. The null pointer dereference can lead to complete application crashes, resulting in denial of service conditions that may affect legitimate users. Attackers could potentially exploit this vulnerability by submitting specially crafted monochrome images that trigger the problematic code path, causing service interruptions or system instability. The vulnerability aligns with ATT&CK technique T1499 which covers network denial of service attacks and can be leveraged as part of broader exploitation campaigns targeting image processing applications.
Mitigation strategies for CVE-2017-11637 should prioritize immediate patching of GraphicsMagick installations to version 1.3.27 or later, which contains the necessary fixes for the null pointer dereference issue. Organizations should implement comprehensive input validation procedures for all image processing workflows, particularly those involving PCL output formats, to prevent malformed image data from reaching vulnerable code paths. Additionally, system administrators should consider implementing application sandboxing and resource limits to contain potential impacts from exploitation attempts. Regular security assessments and vulnerability scanning should be conducted to identify similar issues in other image processing libraries and applications within the environment, as this vulnerability pattern may indicate broader security concerns in the application's handling of external inputs. The fix implemented in subsequent versions typically involves adding proper null pointer checks and defensive programming practices to ensure that all pointer references are validated before access, aligning with established security best practices for preventing memory safety vulnerabilities.