CVE-2020-19481 in MP4Box
Summary
by MITRE • 07/22/2021
An issue was discovered in GPAC before 0.8.0, as demonstrated by MP4Box. It contains an invalid memory read in gf_m2ts_process_pmt in media_tools/mpegts.c that can cause a denial of service via a crafted MP4 file.
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Analysis
by VulDB Data Team • 07/26/2021
The vulnerability identified as CVE-2020-19481 represents a critical memory safety issue within the GPAC multimedia framework, specifically affecting versions prior to 0.8.0. This flaw manifests in the MP4Box utility, which is part of the broader GPAC multimedia toolkit used for processing various digital media formats. The issue stems from improper memory handling during the processing of MPEG-TS (MPEG Transport Stream) files, particularly when parsing Program Map Table (PMT) information. The affected component gf_m2ts_process_pmt function in media_tools/mpegts.c demonstrates a classic invalid memory read condition that occurs when processing maliciously crafted MP4 files designed to exploit this vulnerability.
The technical nature of this vulnerability places it firmly within the category of memory corruption flaws, specifically manifesting as an invalid memory read that can lead to system instability and denial of service conditions. When a crafted MP4 file is processed by MP4Box, the gf_m2ts_process_pmt function attempts to access memory locations that are either uninitialized, freed, or otherwise invalid, causing the application to crash or behave unpredictably. This memory access violation typically results in a segmentation fault or similar memory protection violation that terminates the processing application. The vulnerability is particularly concerning because it can be triggered through normal file processing operations, making it an attractive target for attackers seeking to disrupt multimedia processing services.
From an operational perspective, this vulnerability presents significant risks to organizations relying on GPAC for multimedia processing, particularly in environments where automated file handling or batch processing occurs. The denial of service impact means that legitimate users may experience service interruptions when processing media files, while attackers could potentially exploit this weakness to create persistent availability issues. The vulnerability affects the core multimedia processing capabilities of GPAC, which is widely used in content delivery networks, media servers, and digital asset management systems. The fact that this issue exists in a utility that processes MP4 files makes it particularly dangerous as MP4 is one of the most commonly used video formats across the internet, increasing the potential attack surface significantly.
Organizations should prioritize immediate patching of all affected GPAC installations to mitigate this vulnerability, as the lack of input validation in the memory processing functions creates an exploitable condition. The recommended mitigation strategy involves upgrading to GPAC version 0.8.0 or later, which includes proper bounds checking and memory validation mechanisms. Additionally, implementing file validation procedures that scan for potentially malicious MP4 files before processing can provide an additional layer of protection. Security teams should also consider implementing monitoring for abnormal application termination patterns that could indicate exploitation attempts. This vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and may be categorized under ATT&CK technique T1499.004 for network denial of service attacks. The remediation approach should include comprehensive testing of patched systems to ensure that legitimate media processing continues to function correctly while the memory safety issues are resolved.