CVE-2021-32272 in FAAD2
Summary
by MITRE • 09/20/2021
An issue was discovered in faad2 before 2.10.0. A heap-buffer-overflow exists in the function stszin located in mp4read.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-2021-32272 represents a critical heap buffer overflow condition within the faad2 audio decoding library version 2.9.4 and earlier. This issue resides in the stszin function within the mp4read.c source file, where improper input validation and memory management create exploitable conditions that can lead to arbitrary code execution. The flaw manifests when processing specially crafted mp4 files containing malformed stsz (sample size) atoms, which are part of the mp4 container format specification. The vulnerability stems from insufficient bounds checking during the parsing of sample size information, allowing an attacker to manipulate memory layout through crafted input data.
The technical exploitation of this vulnerability follows a classic heap buffer overflow pattern that aligns with CWE-121, which describes unsafe buffer access conditions. When the stszin function processes sample size entries, it fails to validate the number of entries against available heap memory allocation, enabling attackers to write beyond allocated buffer boundaries. This condition creates opportunities for memory corruption that can be leveraged to overwrite critical program structures, function pointers, or return addresses. The attack vector requires the target system to process a malicious mp4 file through the affected faad2 library, making it particularly dangerous in environments where multimedia file handling is prevalent. The vulnerability demonstrates characteristics consistent with ATT&CK technique T1203, where adversaries exploit memory corruption vulnerabilities to execute arbitrary code.
The operational impact of CVE-2021-32272 extends across multiple system domains where faad2 is integrated, including media players, streaming applications, and multimedia processing frameworks. Systems utilizing this library for audio decoding become susceptible to remote code execution attacks when processing untrusted mp4 content, potentially allowing attackers to gain full system control. The vulnerability affects both desktop and mobile platforms where faad2 is deployed, creating widespread exposure across various device types and operating systems. Organizations relying on multimedia applications that incorporate this library face significant risk, particularly in environments where users might encounter maliciously crafted media files through email attachments, web downloads, or streaming services. The exploitability of this vulnerability is enhanced by the widespread adoption of faad2 in open source multimedia applications, making it a prime target for attackers seeking to compromise large user bases.
Mitigation strategies for CVE-2021-32272 focus primarily on immediate library updates to version 2.10.0 or later, which contain the necessary patches addressing the heap buffer overflow condition. System administrators should prioritize updating all affected applications and frameworks that utilize the faad2 library, particularly those handling multimedia content from untrusted sources. Additional defensive measures include implementing strict input validation for mp4 file processing, deploying network segmentation to limit exposure, and establishing monitoring for suspicious file processing activities. Organizations should also consider implementing sandboxing mechanisms for multimedia file handling, as outlined in ATT&CK technique T1059, to contain potential exploitation attempts. The vulnerability highlights the importance of maintaining up-to-date multimedia libraries and implementing robust security practices in applications that process potentially malicious content, particularly in environments where user-generated media files are common.