CVE-2016-5118 in ImageMagick
Summary
by MITRE
The OpenBlob function in blob.c in GraphicsMagick before 1.3.24 and ImageMagick allows remote attackers to execute arbitrary code via a | (pipe) character at the start of a filename.
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Analysis
by VulDB Data Team • 11/19/2024
The vulnerability identified as CVE-2016-5118 represents a critical command injection flaw affecting two widely-used image processing libraries, GraphicsMagick and ImageMagick. This vulnerability resides within the OpenBlob function in GraphicsMagick's blob.c file and affects versions prior to 1.3.24. The flaw manifests when these libraries process image files that contain a pipe character at the beginning of their filenames, creating a dangerous condition where attacker-controlled input can be interpreted as shell commands rather than file paths. The vulnerability stems from insufficient input validation and sanitization mechanisms that fail to properly escape or reject special characters that could be interpreted by underlying shell operations during file handling processes. This issue is particularly concerning because both GraphicsMagick and ImageMagick are extensively deployed across web applications, content management systems, and server environments where image processing is a common operation.
The technical exploitation of this vulnerability occurs when an application using either library processes an image file whose name begins with a pipe character. When the OpenBlob function encounters such a filename, it passes the unvalidated input directly to shell execution functions without proper sanitization. This allows attackers to inject arbitrary shell commands that will be executed with the privileges of the process running the image library. The vulnerability is classified as a command injection attack pattern under the MITRE ATT&CK framework, specifically falling under the technique of "Command and Scripting Interpreter" with a sub-technique of "Unix Shell" or "Windows Command Shell" depending on the target operating system. The underlying cause maps to CWE-78, which describes improper neutralization of special elements used in OS commands, making this a classic example of how insufficient input validation can lead to arbitrary code execution.
The operational impact of CVE-2016-5118 is severe and far-reaching across numerous systems and applications that rely on these image processing libraries. Web applications that accept user-uploaded images are particularly vulnerable, as attackers can craft malicious filenames that, when processed by the affected libraries, execute arbitrary commands on the server. This could lead to complete system compromise, data exfiltration, privilege escalation, or denial of service conditions. The vulnerability affects not only direct web applications but also any system that utilizes GraphicsMagick or ImageMagick for image processing, including but not limited to content management systems, image hosting services, and server-side image manipulation tools. The remote nature of the attack means that exploitation does not require local access to the system, making it particularly dangerous for publicly accessible web services. Organizations running affected versions of these libraries face significant risk of unauthorized access and potential complete system compromise, as demonstrated by various real-world exploitation attempts targeting vulnerable web applications.
Mitigation strategies for CVE-2016-5118 primarily focus on immediate version upgrades to patched releases of GraphicsMagick or ImageMagick, specifically versions 1.3.24 and later for GraphicsMagick or the corresponding patched versions for ImageMagick. System administrators should also implement additional input validation measures at application layers to reject filenames containing special characters such as pipe symbols, semicolons, or other shell metacharacters before they reach the image processing libraries. Network-level defenses including web application firewalls and intrusion prevention systems can be configured to detect and block requests containing suspicious filename patterns. Organizations should also consider implementing proper file validation and sanitization routines that normalize filenames and remove or escape dangerous characters. The remediation process should include thorough testing of patched versions to ensure that legitimate functionality is preserved while the vulnerability is eliminated. Security monitoring should be enhanced to detect unusual patterns in image processing operations that might indicate exploitation attempts. Additionally, the principle of least privilege should be applied to image processing services, limiting their execution permissions to prevent potential escalation of compromised privileges. This vulnerability serves as a reminder of the critical importance of input validation and the potential for seemingly benign library functions to become attack vectors when proper security controls are not implemented.