CVE-2021-3962 in ImageMagick
Summary
by MITRE • 11/19/2021
A flaw was found in ImageMagick 7.1.0-14 where it did not properly sanitize certain input before using it to invoke convert processes. This flaw allows an attacker to create a specially crafted image that leads to a use-after-free vulnerability when processed by ImageMagick. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.
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Analysis
by VulDB Data Team • 11/22/2021
The vulnerability identified as CVE-2021-3962 represents a critical security flaw within ImageMagick version 7.1.0-14 that stems from inadequate input sanitization during image processing operations. This issue manifests when the software fails to properly validate and sanitize user-supplied input before executing convert processes, creating a pathway for malicious actors to exploit the system through crafted image files. The flaw specifically targets the memory management mechanisms within ImageMagick's processing pipeline, where improper handling of input data can lead to dangerous memory access patterns that compromise system integrity and security.
The technical execution of this vulnerability involves a use-after-free condition that occurs when ImageMagick processes specially crafted image files containing malformed or malicious input data. This memory corruption vulnerability arises from the software's failure to properly validate input parameters before invoking the convert command, which is a fundamental component of ImageMagick's image processing capabilities. When the system attempts to process these malicious inputs, it creates a scenario where memory allocated to certain data structures becomes freed while still being referenced, leading to unpredictable behavior and potential code execution. This particular flaw aligns with CWE-416, which specifically addresses use-after-free vulnerabilities in software systems where memory is accessed after it has been freed, making it particularly dangerous for remote code execution scenarios.
The operational impact of CVE-2021-3962 extends across multiple security domains including confidentiality, integrity, and system availability as indicated in the vulnerability assessment. Attackers can leverage this vulnerability to potentially execute arbitrary code on systems running vulnerable versions of ImageMagick, which could result in complete system compromise. The threat is particularly severe because ImageMagick is widely deployed across various platforms and applications, making the attack surface extensive. Systems that process user-uploaded images, such as web applications, content management systems, and image processing services, become prime targets for exploitation. The vulnerability can be triggered through simple image file uploads, making it particularly dangerous for web applications that do not properly validate or sanitize image inputs before processing them through ImageMagick.
From an attack perspective, this vulnerability maps to several techniques outlined in the MITRE ATT&CK framework, particularly those related to initial access through malicious file uploads and privilege escalation via code execution. The vulnerability enables attackers to perform remote code execution on affected systems, potentially allowing them to establish persistent access, exfiltrate sensitive data, or disrupt system availability. Organizations utilizing ImageMagick in their infrastructure should consider implementing immediate mitigations including version updates, input validation controls, and network segmentation to limit potential attack vectors. The vulnerability demonstrates how seemingly innocuous image processing functionality can become a critical security weakness when proper input sanitization and memory management practices are not implemented. Security teams should also consider implementing monitoring and detection capabilities to identify potential exploitation attempts targeting this vulnerability in their environments.
The remediation approach for CVE-2021-3962 requires immediate deployment of patched versions of ImageMagick that address the input sanitization flaws and memory management issues. Organizations should conduct comprehensive vulnerability assessments to identify all systems running vulnerable versions and prioritize patching based on risk exposure. Additional mitigations include implementing strict input validation controls, sandboxing image processing operations, and deploying web application firewalls that can detect and block malicious image file uploads. The vulnerability serves as a reminder of the critical importance of proper input validation and memory management in security-critical software components, particularly those handling untrusted data from external sources.