CVE-2020-27766 in ImageMagick
Summary
by MITRE • 12/04/2020
A flaw was found in ImageMagick in MagickCore/statistic.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`. 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 7.0.8-69.
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Analysis
by VulDB Data Team • 12/12/2020
The vulnerability identified as CVE-2020-27766 represents a critical undefined behavior flaw within ImageMagick's MagickCore component, specifically in the statistic.c file. This issue stems from improper handling of input data during image processing operations, creating a pathway for malicious actors to manipulate the application's memory management and execution flow. The flaw manifests when ImageMagick processes specially crafted image files that contain malformed statistical data structures, leading to unpredictable memory access patterns and potential system instability.
The technical nature of this vulnerability falls under CWE-704, which encompasses improper type handling and undefined behavior in software systems. When an attacker submits a crafted file, the processing routine in MagickCore attempts to calculate statistical values that exceed the valid range of the unsigned long data type, creating overflow conditions that can corrupt memory structures and cause application crashes or unexpected behavior. The undefined behavior aspect means that the system's response becomes unpredictable and potentially exploitable, as the memory layout and execution flow can be manipulated through carefully constructed input sequences.
From an operational perspective, this vulnerability poses significant risks to applications and systems that rely on ImageMagick for image processing tasks, particularly those handling untrusted user uploads or third-party image content. The impact extends beyond simple application availability issues, as the undefined behavior could potentially be leveraged to execute arbitrary code or cause privilege escalation in certain environments. Systems processing large volumes of images, such as web applications, content management systems, and digital asset management platforms, face the highest risk of exploitation. The flaw's potential for causing system instability means that even a single malicious file could compromise entire service availability, making it particularly dangerous in production environments where uptime is critical.
Organizations should prioritize immediate patching to ImageMagick versions 7.0.8-69 or later, as this update resolves the underlying memory handling issues in the statistic.c file. Additional mitigations include implementing strict file validation and sanitization before image processing, deploying sandboxed execution environments for image handling operations, and establishing robust input filtering mechanisms to prevent malformed files from reaching the ImageMagick processing pipeline. Network-level protections such as content inspection and file type verification can provide additional layers of defense. Security teams should also monitor for potential exploitation attempts through intrusion detection systems and log analysis, as the vulnerability's exploitation patterns may manifest as unusual memory access patterns or application crashes during image processing operations. The ATT&CK framework categorizes this vulnerability under T1203, Exploitation for Client Execution, and T1059, Command and Scripting Interpreter, as it represents a code execution vector through image processing applications.