CVE-2021-21824 in ImageGear
Summary
by MITRE • 06/11/2021
An out-of-bounds write vulnerability exists in the JPG Handle_JPEG420 functionality of Accusoft ImageGear 19.9. A specially crafted malformed file can lead to memory corruption. An attacker can provide a malicious file to trigger this vulnerability.
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Analysis
by VulDB Data Team • 06/14/2021
The vulnerability identified as CVE-2021-21824 represents a critical out-of-bounds write condition within the JPG Handle_JPEG420 functionality of Accusoft ImageGear version 19.9. This flaw resides in the image processing pipeline where the software fails to properly validate input parameters when handling JPEG 4:2:0 chrominance subsampling format. The vulnerability manifests when the application encounters a malformed JPEG file that contains invalid dimension specifications or corrupted data structures within the JPEG marker segments. The out-of-bounds write occurs during the decompression process where the software attempts to write data beyond the allocated memory boundaries intended for storing chrominance components. This type of vulnerability falls under CWE-787, which specifically addresses out-of-bounds write conditions that can result in arbitrary code execution or system instability. The vulnerability is particularly dangerous because it can be triggered through simple file manipulation, requiring no special privileges or complex attack vectors. The memory corruption that results from this out-of-bounds write can overwrite adjacent memory locations, potentially corrupting critical application data structures or even executable code within the process memory space.
The operational impact of this vulnerability extends beyond simple memory corruption, as it creates opportunities for privilege escalation and remote code execution attacks. When an attacker successfully triggers this vulnerability through a maliciously crafted JPEG file, the memory corruption can be leveraged to overwrite function pointers, return addresses, or other critical program state information. This aligns with ATT&CK technique T1059.007 for command and scripting interpreter, where an attacker might attempt to inject malicious code into the memory space of the vulnerable application. The vulnerability is particularly concerning in environments where ImageGear is used for processing untrusted image files, such as web applications, email attachment scanners, or document management systems. Attackers can exploit this vulnerability by preparing a JPEG file with malformed headers that cause the application to write beyond its intended buffer boundaries, potentially leading to complete system compromise. The exploitation requires minimal technical skill since the vulnerability is triggered by standard file processing operations rather than complex injection techniques.
Mitigation strategies for CVE-2021-21824 should focus on both immediate patching and defensive measures. Organizations using Accusoft ImageGear 19.9 should prioritize applying the vendor-provided security update that addresses the out-of-bounds write condition in the JPG Handle_JPEG420 functionality. Until patches are deployed, defensive measures include implementing strict input validation for all image files processed through the application, employing sandboxing techniques to isolate image processing operations, and deploying network-based intrusion detection systems to monitor for suspicious file transfers. The vulnerability demonstrates the importance of proper buffer management and input validation in image processing libraries, as highlighted by CWE-122 which addresses insufficient synchronization of resources. Additional mitigations include restricting file upload capabilities to known good formats, implementing content verification mechanisms, and establishing robust logging and monitoring for file processing activities. Security teams should also consider implementing application whitelisting policies that restrict execution of untrusted image processing modules and ensure that all image handling operations occur within secure memory boundaries. The vulnerability underscores the critical need for regular security assessments of image processing libraries and the implementation of secure coding practices that prevent buffer overflows and memory corruption conditions in multimedia applications.