CVE-2020-27751 in ImageMagick
Summary
by MITRE • 12/09/2020
A flaw was found in ImageMagick in MagickCore/quantum-export.c. An attacker who submits a crafted file that is processed by ImageMagick could trigger undefined behavior in the form of values outside the range of type `unsigned long long` as well as a shift exponent that is too large for 64-bit type. This would most likely lead to an impact to application availability, but could potentially cause other problems related to undefined behavior. This flaw affects ImageMagick versions prior to 7.0.9-0.
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Analysis
by VulDB Data Team • 12/14/2020
The vulnerability identified as CVE-2020-27751 represents a critical memory safety issue within ImageMagick's MagickCore component, specifically in the quantum-export.c file. This flaw manifests as a result of improper handling of data processing operations that exceed the bounds of standard data types, creating conditions where applications may experience unpredictable behavior and system instability. The vulnerability exists in versions of ImageMagick prior to 7.0.9-0, making it a significant concern for organizations that have not updated their imaging software to the patched version. The flaw demonstrates characteristics consistent with memory corruption vulnerabilities that can be exploited through crafted input files processed by the vulnerable software.
The technical implementation of this vulnerability stems from the improper validation of shift operations and value assignments within the quantum export functionality. When processing specially crafted files, the software attempts to perform bit shifting operations with exponents that exceed the maximum allowable value for 64-bit unsigned long long data types. Additionally, the code generates values that fall outside the valid range of unsigned long long integers, leading to undefined behavior patterns that can manifest as memory corruption or application crashes. This type of vulnerability falls under CWE-191, which specifically addresses integer underflow and overflow conditions, and CWE-194, which deals with unexpected signedness of integer values during operations. The flaw demonstrates how improper input validation can lead to fundamental data type violations that compromise system stability.
The operational impact of CVE-2020-27751 extends beyond simple application crashes to potentially enable more sophisticated attack vectors. While the primary effect manifests as application availability issues, the undefined behavior introduced by this vulnerability could potentially be leveraged to achieve arbitrary code execution in certain circumstances. Attackers who can submit crafted files to systems running vulnerable versions of ImageMagick could trigger memory corruption that might be exploitable for privilege escalation or denial of service attacks. The vulnerability affects systems where ImageMagick is used as a backend processing component, including web applications, content management systems, and automated image processing pipelines. This aligns with ATT&CK technique T1203, which covers exploitation of software vulnerabilities for privilege escalation, and T1499, which addresses the use of application or system exploitation for availability impact.
Organizations should prioritize immediate remediation by upgrading to ImageMagick version 7.0.9-0 or later, which contains the necessary patches to address the quantum export handling issues. System administrators should implement comprehensive vulnerability scanning procedures to identify all instances of vulnerable ImageMagick installations across their infrastructure, particularly in web-facing applications and automated processing environments. Additional mitigations include implementing strict input validation for all image files processed through ImageMagick, deploying sandboxed environments for image processing operations, and establishing monitoring protocols to detect anomalous behavior patterns that might indicate exploitation attempts. Network segmentation and access controls should be implemented to limit exposure of systems that process untrusted image files, reducing the attack surface for potential exploitation of this vulnerability.