CVE-2019-20091 in Bento4
Summary
by MITRE
An issue was discovered in Bento4 1.5.1.0. There is a NULL pointer dereference in AP4_Descriptor::GetTag in mp42ts when called from AP4_DecoderConfigDescriptor::GetDecoderSpecificInfoDescriptor in Ap4DecoderConfigDescriptor.cpp.
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Analysis
by VulDB Data Team • 03/18/2024
The vulnerability identified as CVE-2019-20091 represents a critical NULL pointer dereference flaw within the Bento4 multimedia processing library version 1.5.1.0. This issue specifically manifests in the mp42ts component where the AP4_Descriptor::GetTag method fails to properly validate pointer references before dereferencing them. The flaw occurs when the AP4_DecoderConfigDescriptor::GetDecoderSpecificInfoDescriptor function in the Ap4DecoderConfigDescriptor.cpp file invokes the problematic GetTag method, creating a scenario where memory access violations can occur during normal media file processing operations. The vulnerability stems from inadequate input validation and error handling mechanisms within the library's descriptor parsing routines, which are fundamental components responsible for interpreting and processing multimedia container formats.
The technical implementation of this vulnerability exposes the underlying architecture of Bento4's descriptor handling system where multiple layers of abstraction fail to perform proper null checks before accessing object members. When processing certain malformed or specially crafted media files, the decoder configuration descriptor parsing logic encounters a scenario where a pointer that should contain valid descriptor data becomes NULL, yet the code proceeds to dereference it without validation. This pattern aligns with CWE-476, which specifically addresses NULL pointer dereference vulnerabilities in software systems. The flaw demonstrates a classic failure in defensive programming practices where assumptions about pointer validity are made without proper verification mechanisms, creating a potential crash condition that can be exploited by malicious actors.
The operational impact of this vulnerability extends beyond simple application crashes, as it can be leveraged to disrupt services or potentially enable more sophisticated attack vectors. When a malicious actor crafts a specially formatted media file that triggers this NULL pointer dereference, the target system running Bento4-based applications will experience a segmentation fault or access violation, leading to service disruption and potential denial of service conditions. This vulnerability is particularly concerning in environments where Bento4 is used for automated media processing, content delivery networks, or streaming services, as it could be exploited to systematically disrupt operations. The ATT&CK framework categorizes this as a system service disruption technique, where adversaries can manipulate application behavior to achieve availability attacks against multimedia processing infrastructure.
Mitigation strategies for CVE-2019-20091 should focus on immediate patch application and defensive programming enhancements. Organizations using Bento4 should prioritize updating to versions that contain fixed implementations of the descriptor parsing logic, specifically addressing the missing null pointer validation in AP4_Descriptor::GetTag method. Additionally, implementing input sanitization measures and robust error handling within applications that utilize Bento4 can provide additional protection layers. The fix should incorporate proper null checks before pointer dereferencing operations, ensuring that all descriptor parsing routines validate their inputs and handle edge cases gracefully. Security monitoring should also be enhanced to detect unusual patterns in media file processing that might indicate exploitation attempts, as this vulnerability could serve as a precursor to more complex attacks targeting multimedia processing pipelines.