CVE-2018-20196 in Freeware Advanced Audio Decoder
Summary
by MITRE
There is a stack-based buffer overflow in the third instance of the calculate_gain function in libfaad/sbr_hfadj.c in Freeware Advanced Audio Decoder 2 (FAAD2) 2.8.8. A crafted input will lead to a denial of service or possibly unspecified other impact because the S_M array is mishandled.
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Analysis
by VulDB Data Team • 06/19/2023
The vulnerability identified as CVE-2018-20196 represents a critical stack-based buffer overflow within the Freeware Advanced Audio Decoder 2 version 2.8.8 library. This flaw specifically manifests in the calculate_gain function located in the libfaad/sbr_hfadj.c source file, where improper handling of the S_M array creates exploitable conditions that can compromise system stability and security. The issue arises from inadequate bounds checking during audio frame processing, particularly when handling sophisticated audio data structures that require precise memory management. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, which occurs when more data is written to a buffer than it can accommodate, leading to memory corruption that can be exploited by malicious actors. This particular implementation flaw demonstrates a fundamental weakness in memory boundary validation within audio decoding libraries, which are widely used across multimedia applications and systems.
The technical exploitation of this vulnerability occurs when a maliciously crafted audio file is processed by the FAAD2 library, triggering the buffer overflow condition during the S_M array manipulation phase of the calculate_gain function. The stack-based nature of this overflow means that the corrupted memory includes return addresses and function parameters, potentially allowing attackers to redirect program execution flow or cause system crashes. The impact extends beyond simple denial of service to include potential code execution or arbitrary code loading, depending on the specific system configuration and memory layout. This vulnerability demonstrates the classic attack pattern where audio processing libraries become attack vectors due to insufficient input validation and memory safety mechanisms. The ATT&CK framework categorizes this under T1203 as legitimate program execution, where adversaries leverage existing software capabilities to perform unauthorized operations.
The operational impact of CVE-2018-20196 is significant across multiple domains where FAAD2 is integrated, including media players, streaming services, and embedded audio systems. Systems that process user-uploaded audio content or automatically decode media files become particularly vulnerable, as the attack vector requires only the delivery of a malicious audio file rather than complex network-based exploitation. The vulnerability affects both desktop and mobile platforms where FAAD2 is implemented, creating widespread exposure across multimedia applications and devices. Organizations using FAAD2 in their audio processing pipelines must consider the potential for remote code execution and system compromise, especially in environments where untrusted audio content is processed. The memory corruption resulting from this flaw can lead to unpredictable behavior including application crashes, data corruption, or complete system instability. The vulnerability's exploitation potential is amplified by the fact that FAAD2 is a widely deployed library, making the impact scale across numerous applications and platforms. Security professionals should prioritize patching or mitigating this vulnerability due to its potential for both denial of service and more severe security implications.
Mitigation strategies for CVE-2018-20196 should include immediate application of vendor patches or updates to FAAD2 version 2.8.9 or later, which contain the necessary fixes for the buffer overflow condition. System administrators should implement input validation measures that restrict audio file formats and sizes when processing user-uploaded content, reducing the attack surface. Network-based protections can be implemented through content filtering systems that scan audio files for known malicious patterns before processing. Additionally, memory safety enhancements such as stack canaries, address space layout randomization, and heap-based memory protection mechanisms should be enabled to provide additional defense-in-depth layers. Organizations should conduct thorough vulnerability assessments to identify all systems utilizing FAAD2 and ensure proper patch management protocols are in place. The implementation of automated monitoring systems that detect unusual memory access patterns or application crashes can provide early warning of potential exploitation attempts. Regular security updates and penetration testing should be conducted to verify that the implemented mitigations remain effective against evolving threat landscapes.