CVE-2017-9220 in Freeware Advanced Audio Decoder
Summary
by MITRE
The mp4ff_read_stco function in common/mp4ff/mp4atom.c in Freeware Advanced Audio Decoder 2 (FAAD2) 2.7 allows remote attackers to cause a denial of service (memory allocation error) via a crafted mp4 file.
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Analysis
by VulDB Data Team • 10/20/2019
The vulnerability identified as CVE-2017-9220 resides within the Freeware Advanced Audio Decoder 2 version 2.7, specifically in the mp4ff_read_stco function located in the common/mp4ff/mp4atom.c file. This flaw represents a critical security issue that enables remote attackers to execute denial of service attacks through the manipulation of specially crafted mp4 files. The vulnerability stems from improper handling of memory allocation during the processing of mp4 file structures, particularly when parsing the stco (sample table chunk offset) atom within mp4 containers. The mp4ff_read_stco function fails to adequately validate input parameters and allocate memory resources, creating a scenario where maliciously constructed mp4 files can trigger excessive memory allocation requests that exceed system capabilities.
The technical nature of this vulnerability aligns with CWE-704, which describes improper type conversion or cast vulnerabilities, and more specifically relates to CWE-122, which covers heap-based buffer overflow conditions. The flaw operates by exploiting the lack of proper bounds checking in the memory allocation process, allowing attackers to craft mp4 files that contain malformed stco atom data. When the FAAD2 decoder attempts to parse these crafted files, the mp4ff_read_stco function processes the invalid data and attempts to allocate memory based on incorrect size calculations derived from the malformed input. This results in either excessive memory consumption that leads to system resource exhaustion or memory allocation failures that cause the application to crash and become unavailable to legitimate users.
The operational impact of CVE-2017-9220 extends beyond simple service disruption as it affects any system utilizing FAAD2 for mp4 file processing, including media players, streaming services, and content delivery networks. Attackers can exploit this vulnerability remotely by simply providing a maliciously crafted mp4 file to any application that relies on FAAD2 for audio decoding, making it particularly dangerous in environments where users can upload or download media content. The vulnerability is especially concerning in web applications and media processing pipelines where user-supplied content is automatically processed, as it allows for easy exploitation without requiring specialized knowledge or privileged access. Systems that do not properly validate mp4 file inputs before processing are at risk of experiencing complete service outages, making this a significant threat to availability in media processing environments.
Mitigation strategies for CVE-2017-9220 should focus on immediate patching of affected FAAD2 versions, as the vulnerability has been addressed in subsequent releases. Organizations should implement input validation mechanisms that check mp4 file structures before processing, particularly focusing on the stco atom parsing and memory allocation behaviors. The implementation of resource limits and memory allocation constraints can help prevent excessive memory consumption during file processing, while sandboxing techniques can isolate the decoding process to contain potential impacts. Additionally, deploying intrusion detection systems that monitor for suspicious mp4 file patterns and implementing proper access controls for media processing services can provide layered defense against exploitation attempts. From an ATT&CK perspective, this vulnerability maps to T1499.004, which covers network denial of service attacks, and T1595.001, related to network scanning and reconnaissance activities that may precede exploitation attempts. Organizations should also consider updating their security monitoring tools to detect anomalous memory allocation patterns that may indicate exploitation attempts.