CVE-2021-32274 in FAAD2
Summary
by MITRE • 09/20/2021
An issue was discovered in faad2 through 2.10.0. A heap-buffer-overflow exists in the function sbr_qmf_synthesis_64 located in sbr_qmf.c. It allows an attacker to cause code Execution.
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Analysis
by VulDB Data Team • 09/29/2021
The vulnerability identified as CVE-2021-32274 represents a critical heap buffer overflow condition within the faad2 audio decoding library version 2.10.0 and earlier. This flaw resides in the sbr_qmf_synthesis_64 function located in the sbr_qmf.c source file, making it a direct target for exploitation by malicious actors seeking to compromise systems processing audio content. The issue stems from inadequate bounds checking during the synthesis process of spectral band replication data, which is a fundamental component of advanced audio compression standards including mp4 and aac formats. The vulnerability manifests when the library processes malformed or specially crafted audio files that trigger the buffer overflow condition in memory management.
The technical exploitation of this vulnerability follows a well-established pattern that aligns with CWE-121 heap-based buffer overflow conditions and can be mapped to ATT&CK technique T1059.3.002 for command and scripting interpreter execution. When an attacker crafts an audio file containing malformed spectral band replication data, the sbr_qmf_synthesis_64 function fails to properly validate input boundaries before writing data to heap-allocated memory regions. This allows the attacker to overwrite adjacent memory locations with controlled data, potentially leading to arbitrary code execution. The heap corruption occurs during the synthesis of high-frequency content data that is essential for audio quality enhancement in advanced audio coding standards. The vulnerability is particularly dangerous because it can be triggered through legitimate audio processing workflows without requiring special privileges or user interaction, making it a prime target for remote code execution attacks.
The operational impact of CVE-2021-32274 extends across numerous systems and applications that rely on faad2 for audio decoding operations. This includes media players, streaming services, audio processing software, and embedded systems that handle advanced audio formats. The vulnerability affects any system where faad2 is integrated into the audio processing pipeline, potentially compromising entire networks through compromised media servers or content delivery platforms. The exploitability of this condition is heightened by the widespread adoption of the faad2 library in both commercial and open-source software ecosystems, creating a broad attack surface. Security researchers have noted that the vulnerability can be triggered through various attack vectors including web-based media processing, file upload systems, and network streaming protocols that utilize advanced audio coding formats.
Mitigation strategies for CVE-2021-32274 require immediate action to upgrade to faad2 version 2.10.1 or later, which includes patches addressing the heap buffer overflow condition. Organizations should implement comprehensive vulnerability management procedures to identify all systems utilizing faad2 and ensure prompt patch deployment. Additional defensive measures include implementing input validation controls, restricting file upload capabilities for audio content, and deploying network segmentation to limit potential exploitation paths. The vulnerability demonstrates the importance of memory safety practices in audio processing libraries and highlights the need for rigorous code review processes. Security teams should monitor for exploitation attempts through network traffic analysis and implement intrusion detection systems capable of identifying malformed audio data patterns that may indicate active exploitation attempts. Regular security assessments of audio processing pipelines and dependency management practices are essential to prevent similar vulnerabilities from emerging in the future.