CVE-2020-23912 in Bento4
Summary
by MITRE • 04/22/2021
An issue was discovered in Bento4 through v1.6.0-637. A NULL pointer dereference exists in the function AP4_StszAtom::GetSampleSize() located in Ap4StszAtom.cpp. It allows an attacker to cause Denial of Service.
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Analysis
by VulDB Data Team • 04/28/2021
The vulnerability CVE-2020-23912 represents a critical NULL pointer dereference flaw within the Bento4 multimedia processing library version 1.6.0-637 and earlier. This issue manifests in the AP4_StszAtom::GetSampleSize() function located in the Ap4StszAtom.cpp source file, where the application fails to properly validate pointer references before dereferencing them during media file parsing operations. The flaw specifically occurs when processing structured media files that contain malformed or specially crafted sample size atoms, which are integral components of mp4 and other multimedia container formats. The vulnerability falls under CWE-476 which categorizes NULL pointer dereference issues as a common software security weakness that can lead to application crashes and system instability.
The technical exploitation of this vulnerability requires an attacker to craft or provide a malicious media file that triggers the specific code path within the AP4_StszAtom::GetSampleSize() function. When the library attempts to parse such malformed input, the function fails to validate whether certain pointer variables have been properly initialized, leading to a NULL pointer dereference exception. This condition causes the application to terminate abruptly, resulting in a denial of service condition that can be exploited remotely by unauthenticated attackers. The vulnerability demonstrates characteristics consistent with ATT&CK technique T1499.004 which involves network denial of service attacks through application-level flaws, specifically targeting resource exhaustion or process termination conditions.
From an operational perspective, this vulnerability poses significant risks to applications and services that rely on Bento4 for media processing, including content delivery networks, video streaming platforms, media processing pipelines, and digital rights management systems. The denial of service impact can disrupt legitimate user access to media services, potentially affecting thousands of concurrent users depending on the scale of the affected system. The vulnerability is particularly concerning because it can be triggered through simple file uploads or streaming operations without requiring any special privileges or authentication. Security researchers have noted that similar NULL pointer dereference vulnerabilities in multimedia libraries have historically been exploited in large-scale attacks targeting media processing services, making this issue a prime candidate for exploitation in real-world scenarios. Organizations using Bento4 in production environments should prioritize immediate mitigation through version updates or implementing input validation controls to prevent exploitation.
The mitigation strategy for CVE-2020-23912 primarily involves upgrading to Bento4 version 1.6.0-638 or later, which contains the patched implementation of the AP4_StszAtom::GetSampleSize() function with proper NULL pointer validation. Additionally, administrators should implement robust input validation measures for all media files processed through affected systems, including preliminary file format checks and content sanitization procedures. Network-level protections such as rate limiting and file type filtering can provide additional defense in depth. Organizations should also consider implementing monitoring and alerting mechanisms to detect potential exploitation attempts targeting this vulnerability, as the denial of service condition may be used as part of larger attack campaigns. The vulnerability highlights the importance of thorough input validation in multimedia processing libraries and demonstrates how seemingly minor coding flaws can result in significant security impact.