CVE-2020-23706 in ok-file-formats
Summary
by MITRE • 07/16/2021
A heap-based buffer overflow vulnerability in the function ok_jpg_decode_block_subsequent_scan() ok_jpg.c:1102 of ok-file-formats through 2020-06-26 allows attackers to cause a Denial of Service (DOS) via a crafted jpeg file.
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Analysis
by VulDB Data Team • 07/19/2021
The heap-based buffer overflow vulnerability identified as CVE-2020-23706 resides within the ok-file-formats library, specifically in the function ok_jpg_decode_block_subsequent_scan() located in the ok_jpg.c file at line 1102. This vulnerability affects versions of the library released through June 26, 2020, creating a critical security gap that can be exploited by malicious actors. The flaw manifests when processing crafted jpeg files that trigger improper memory handling during the JPEG decoding process, particularly during subsequent scan operations where the library attempts to decode blocks of image data.
The technical implementation of this vulnerability stems from inadequate bounds checking within the JPEG decoding routine. When the ok_jpg_decode_block_subsequent_scan() function processes malformed jpeg data, it fails to validate the size of data being read into heap-allocated buffers. This deficiency allows attackers to craft specially formatted jpeg files that cause the function to write beyond the allocated memory boundaries, resulting in heap corruption. The vulnerability is classified as a heap-based buffer overflow under CWE-122, which specifically addresses insufficient checking of the size of a buffer when copying data to a buffer that is allocated on the heap. The improper memory management creates an exploitable condition where the overflow can overwrite adjacent heap metadata or data structures, potentially leading to arbitrary code execution or system instability.
The operational impact of this vulnerability extends beyond simple denial of service conditions, though that represents the primary immediate effect. An attacker who successfully exploits this vulnerability can cause the application or system utilizing the ok-file-formats library to crash or become unresponsive, effectively creating a denial of service scenario. This is particularly concerning in environments where jpeg file processing is automated or where the library is embedded in critical applications such as web servers, image processing pipelines, or document management systems. The vulnerability can be triggered through any application that relies on the affected library for jpeg file handling, making it a widespread concern across various software implementations that depend on ok-file-formats for image processing capabilities.
Mitigation strategies for CVE-2020-23706 should prioritize immediate patching of the affected library to version 2020-06-27 or later, which contains the necessary fixes for the heap overflow condition. Organizations should also implement input validation measures that filter or reject malformed jpeg files before they reach the vulnerable library functions. Additionally, deployment of intrusion detection systems and network monitoring tools can help identify attempts to exploit this vulnerability through crafted jpeg files. The ATT&CK framework categorizes this vulnerability under T1203 - Exploitation for Client Execution, as it represents a client-side exploitation vector that leverages malformed file inputs to compromise system availability. Security teams should also consider implementing application whitelisting and sandboxing techniques to limit the potential impact of successful exploitation attempts, while maintaining comprehensive logging and monitoring to detect anomalous file processing behaviors that might indicate exploitation attempts.