CVE-2021-21795 in ImageGear
Summary
by MITRE • 06/11/2021
A heap-based buffer overflow vulnerability exists in the PSD read_icc_icCurve_data functionality of Accusoft ImageGear 19.9. A specially crafted malformed file can lead to an integer overflow that, in turn, leads to a heap buffer overflow. An attacker can provide a malicious file to trigger this vulnerability.
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Analysis
by VulDB Data Team • 06/14/2021
The heap-based buffer overflow vulnerability identified as CVE-2021-21795 resides within the PSD read_icc_icCurve_data functionality of Accusoft ImageGear version 19.9, representing a critical security flaw that undermines the software's image processing capabilities. This vulnerability stems from inadequate input validation mechanisms within the color profile handling code, specifically when processing ICC (International Color Consortium) curve data embedded within PSD (Photoshop Document) files. The flaw manifests when the application attempts to parse malformed ICC curve data structures, creating a dangerous condition where integer overflow can occur during memory allocation calculations. The vulnerability is classified under CWE-121 as a heap-based buffer overflow, which occurs when insufficient bounds checking allows a program to write beyond allocated memory boundaries, potentially corrupting adjacent memory regions. According to the ATT&CK framework, this vulnerability aligns with T1203 - Exploitation for Client Execution, as it enables remote code execution through malicious file delivery, and T1068 - Exploitation for Privilege Escalation when successful exploitation occurs.
The technical implementation of this vulnerability involves a specific sequence of operations that begins with parsing ICC curve data structures within PSD files, where the application fails to properly validate the size parameters of curve data elements. When processing malformed input, the integer overflow occurs during the calculation of memory allocation sizes for the curve data buffer, leading to insufficiently allocated memory regions that subsequently overflow when the application attempts to populate them with actual data. This integer overflow condition typically arises from the application treating unsigned integer values as signed during arithmetic operations, or failing to check for overflow conditions during multiplication operations that determine buffer sizes. The heap buffer overflow then occurs when the application attempts to write data beyond the allocated memory boundaries, potentially overwriting critical program data structures, function pointers, or return addresses within the heap memory layout. The vulnerability is particularly dangerous because it can be triggered through simple file manipulation, requiring no complex exploitation techniques beyond crafting a malicious PSD file with malformed ICC curve data.
The operational impact of CVE-2021-21795 extends beyond simple denial of service scenarios, as successful exploitation can lead to complete system compromise and unauthorized code execution within the context of the vulnerable application. Attackers can leverage this vulnerability by delivering malicious PSD files through various attack vectors including email attachments, web downloads, or file sharing platforms, making it particularly dangerous in enterprise environments where image processing applications are commonly used. The vulnerability affects any system running Accusoft ImageGear 19.9 that processes PSD files, including web applications, desktop software, and server-based image processing systems. The exploitability of this vulnerability is enhanced by the fact that PSD files are commonly used in graphic design workflows and content management systems, providing numerous attack surfaces for potential exploitation. The memory corruption resulting from heap overflow can lead to unpredictable application behavior, including crashes, data corruption, or more critically, remote code execution when function pointers or return addresses are overwritten.
Mitigation strategies for CVE-2021-21795 should prioritize immediate software updates and patches from Accusoft, as the vendor has likely released remediation measures addressing the integer overflow and buffer overflow conditions. Organizations should implement defensive measures including input validation for all image file processing, network segmentation to limit exposure of vulnerable systems, and application whitelisting to prevent execution of untrusted image files. The implementation of sandboxing techniques for image processing operations can provide additional protection layers, while regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other image processing libraries. Network-based intrusion detection systems should be configured to monitor for suspicious file transfers and processing patterns that might indicate exploitation attempts. Security teams should also consider implementing automated patch management processes to ensure timely deployment of security updates across all affected systems. The vulnerability serves as a reminder of the importance of proper integer overflow protection and bounds checking in memory management operations, particularly within image processing and multimedia applications that handle complex data structures with variable-length elements.