CVE-2019-15296 in Freeware Advanced Audio Decoder
Summary
by MITRE
An issue was discovered in Freeware Advanced Audio Decoder 2 (FAAD2) 2.8.8. The faad_resetbits function in libfaad/bits.c is affected by a buffer overflow vulnerability. The number of bits to be read is determined by ld->buffer_size - words*4, cast to uint32. If ld->buffer_size - words*4 is negative, a buffer overflow is later performed via getdword_n(&ld->start[words], ld->bytes_left).
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Analysis
by VulDB Data Team • 11/27/2023
The vulnerability identified as CVE-2019-15296 resides within the Freeware Advanced Audio Decoder 2 (FAAD2) version 2.8.8, specifically within the libfaad/bits.c module. This issue represents a critical buffer overflow flaw that can potentially lead to arbitrary code execution or system compromise when processing maliciously crafted audio files. The vulnerability manifests in the faad_resetbits function where improper input validation and arithmetic operations create conditions that allow attackers to manipulate memory boundaries during audio decoding operations.
The technical root cause of this vulnerability stems from an unsafe arithmetic operation involving the calculation of bits to be read from a buffer. The system computes the bit count using the formula ld->buffer_size - words*4, which is then cast to uint32 type without proper bounds checking. When the calculated value becomes negative due to buffer size constraints or malformed input data, the subsequent getdword_n function call executes with invalid parameters, leading to memory corruption. This particular implementation flaw allows attackers to bypass normal buffer boundary checks and write data beyond allocated memory regions, creating opportunities for exploitation.
The operational impact of CVE-2019-15296 extends beyond simple denial of service conditions to encompass potential remote code execution capabilities. Systems utilizing FAAD2 for audio decoding, including media players, streaming services, and embedded devices, become vulnerable to attacks that could result in complete system compromise. The vulnerability is particularly concerning because it can be triggered through standard audio file processing operations, meaning that simply opening or playing a maliciously crafted audio file could lead to exploitation. This makes the vulnerability highly relevant in environments where users might encounter untrusted audio content from various sources including web applications, email attachments, or file sharing platforms.
Mitigation strategies for this vulnerability should focus on immediate patching of FAAD2 installations to version 2.8.9 or later, which contains the necessary fixes for the buffer overflow condition. Organizations should implement comprehensive input validation for all audio processing components and consider deploying runtime protections such as address space layout randomization and stack canaries. Additionally, security teams should monitor for exploitation attempts through network traffic analysis and implement proper access controls to limit exposure of systems that process audio content. This vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of how improper input validation can lead to memory corruption vulnerabilities. The attack surface for this issue is broad due to FAAD2's widespread adoption in various multimedia applications, making prompt remediation essential for maintaining system security posture.