CVE-2017-9255 in Freeware Advanced Audio Decoder
Summary
by MITRE
The mp4ff_read_stsc 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-2017-9255 resides within the Freeware Advanced Audio Decoder 2 version 2.7, specifically in the mp4ff_read_stsc function located in the common/mp4ff/mp4atom.c file. This decoder is widely used for processing audio files in various multimedia applications and systems. The flaw manifests when processing specially crafted mp4 files that contain malformed stsc (sample to chunk) atom data, which is a critical component in mp4 file structure defining how samples are mapped to chunks. The vulnerability represents a classic denial of service scenario where an attacker can craft malicious mp4 files that trigger excessive computational resource consumption.
The technical implementation of this vulnerability stems from inadequate input validation within the mp4ff_read_stsc function. When the decoder encounters a crafted mp4 file, the stsc atom data contains values that cause the function to enter an unexpectedly large loop during processing. This loop consumes excessive CPU cycles and memory resources, effectively causing the application to become unresponsive or crash. The flaw is classified as a CWE-835 loop with unbounded iteration, where the number of iterations in the loop is not properly bounded by input validation checks. The vulnerability does not involve memory corruption or arbitrary code execution, but rather exploits the decoder's processing logic to create a resource exhaustion condition that leads to denial of service.
The operational impact of this vulnerability extends across numerous systems and applications that rely on FAAD2 for audio processing, including media players, streaming services, content management systems, and multimedia applications. Attackers can exploit this vulnerability by distributing malicious mp4 files through various channels such as email attachments, file sharing platforms, or web downloads. When these files are processed by vulnerable applications, the affected systems experience significant performance degradation or complete service interruption. This makes the vulnerability particularly dangerous in environments where automated processing of user-uploaded content occurs, as it can be exploited to disrupt services at scale. The vulnerability affects both desktop and server environments, making it a critical concern for organizations maintaining multimedia content platforms.
Mitigation strategies for CVE-2017-9255 involve multiple layers of protection including immediate software updates, input validation enhancements, and operational security measures. Organizations should prioritize upgrading to FAAD2 versions that contain the patched mp4ff_read_stsc function, which implements proper bounds checking and input validation for stsc atom data. Additionally, implementing input sanitization mechanisms that limit the size and complexity of processed mp4 files can prevent exploitation. Network-based protections such as content filtering and sandboxing techniques can also reduce the risk of exploitation. The vulnerability aligns with ATT&CK technique T1499.001 which involves resource exhaustion attacks, and organizations should consider implementing monitoring for unusual CPU consumption patterns that may indicate exploitation attempts. System administrators should also establish regular vulnerability scanning procedures to identify and remediate similar issues in other multimedia processing components.