CVE-2017-9257 in Freeware Advanced Audio Decoder
Summary
by MITRE
The mp4ff_read_ctts function in common/mp4ff/mp4atom.c in Freeware Advanced Audio Decoder 2 (FAAD2) 2.7 allows remote attackers to cause a denial of service (large loop and CPU consumption) via a crafted mp4 file.
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Analysis
by VulDB Data Team • 10/21/2019
The vulnerability identified as CVE-2017-9257 resides within the Freeware Advanced Audio Decoder 2 version 2.7, specifically in the mp4ff_read_ctts function located in the common/mp4ff/mp4atom.c file. This flaw represents a classic denial of service vulnerability that can be exploited through carefully crafted mp4 media files. The affected component serves as a core parser for mp4 container format handling within the FAAD2 audio decoding library, which is widely used for decoding advanced audio coding formats including aac and mp4 audio streams.
The technical nature of this vulnerability stems from inadequate input validation and loop bounds checking within the mp4ff_read_ctts function. When processing a maliciously constructed mp4 file, the function enters into a computationally intensive loop that consumes excessive cpu resources without proper termination conditions. This occurs because the parser fails to validate the length values contained within the ctts (composition time to sample) atom of the mp4 file structure, allowing attackers to specify artificially large loop iterations that can cause the decoder to consume massive amounts of processing time. The vulnerability manifests as a resource exhaustion attack where the target system becomes unresponsive due to the excessive cpu utilization.
The operational impact of CVE-2017-9257 extends beyond simple denial of service, as it can affect any system or application that utilizes FAAD2 for mp4 audio processing. This includes media players, streaming servers, content delivery networks, and mobile applications that handle mp4 audio files. Attackers can exploit this vulnerability by crafting specially formatted mp4 files that trigger the problematic code path, potentially causing legitimate services to become unavailable. The vulnerability is particularly concerning in server environments where multiple concurrent requests could be processed simultaneously, leading to cascading denial of service conditions that affect entire service availability.
Mitigation strategies for this vulnerability should focus on input validation and bounds checking within the affected parser. The most effective immediate solution involves updating to FAAD2 version 2.8 or later, which includes proper bounds checking and loop termination conditions for the ctts atom processing. Organizations should also implement file validation mechanisms that scan mp4 files for suspicious atom structures before processing them, particularly in environments where untrusted media content is handled. Additionally, system administrators should consider implementing resource limits and cpu monitoring to detect and prevent exploitation attempts. This vulnerability aligns with CWE-772 (Missing Release of Resource after Effective Lifetime) and can be categorized under ATT&CK technique T1499.004 (Endpoint Denial of Service) in the attack framework, representing a common pattern of resource exhaustion attacks that target media processing libraries.