CVE-2018-20195 in Freeware Advanced Audio Decoder
Summary
by MITRE
A NULL pointer dereference was discovered in ic_predict of libfaad/ic_predict.c in Freeware Advanced Audio Decoder 2 (FAAD2) 2.8.8. The vulnerability causes a segmentation fault and application crash, which leads to denial of service.
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Analysis
by VulDB Data Team • 06/19/2023
The vulnerability identified as CVE-2018-20195 represents a critical null pointer dereference flaw within the Freeware Advanced Audio Decoder 2 version 2.8.8 implementation. This issue specifically manifests within the ic_predict function located in the libfaad/ic_predict.c source file, which forms a core component of the FAAD2 audio decoding library. The flaw occurs when the decoder processes malformed or specially crafted audio files that trigger unexpected execution paths during the inverse coding prediction phase of audio decoding operations. This particular vulnerability demonstrates the classic characteristics of a denial of service condition where legitimate application execution terminates abruptly due to improper memory access patterns.
The technical nature of this vulnerability aligns with CWE-476, which categorizes null pointer dereference conditions as a fundamental programming error that can lead to system instability and application crashes. When the ic_predict function attempts to dereference a null pointer during audio frame processing, the operating system generates a segmentation fault that terminates the application process. This behavior constitutes a direct violation of proper error handling protocols and memory management practices that should be implemented in robust audio decoding software. The flaw specifically affects the decoder's ability to handle edge cases in audio data structure parsing, particularly within the context of AAC (Advanced Audio Coding) file processing where prediction coefficients are utilized for efficient audio compression.
The operational impact of CVE-2018-20195 extends beyond simple application crashes to encompass broader system reliability concerns within environments that rely on FAAD2 for audio processing. Systems utilizing this decoder for media playback, streaming services, or audio conversion applications become vulnerable to denial of service attacks where maliciously crafted audio files can be used to crash applications or entire systems. This vulnerability affects both desktop and embedded systems that incorporate FAAD2 as part of their audio processing pipeline, potentially impacting media players, streaming servers, and multimedia applications across various operating systems. The vulnerability's exploitation requires minimal prerequisites, making it particularly dangerous as it can be triggered through simple file playback operations without requiring specialized knowledge or complex attack vectors.
From an adversarial perspective, this vulnerability maps to ATT&CK technique T1499.004 which involves network denial of service attacks through the exploitation of application vulnerabilities. The null pointer dereference can be effectively weaponized in scenarios where attackers control or influence the audio content being processed by vulnerable applications, potentially leading to service disruption in multimedia environments. Security practitioners should note that this vulnerability demonstrates the importance of input validation and proper error handling in multimedia processing libraries, as similar patterns may exist in other components of the FAAD2 library or related audio decoding software. The flaw underscores the necessity of rigorous testing procedures including fuzzing and boundary condition analysis to identify potential null pointer dereference scenarios that could compromise system availability. Mitigation strategies should focus on updating to patched versions of FAAD2, implementing proper input validation mechanisms, and deploying application sandboxing techniques to limit the impact of potential exploitation attempts.