CVE-2017-9222 in Freeware Advanced Audio Decoder
Summary
by MITRE
The mp4ff_parse_tag function in common/mp4ff/mp4meta.c in Freeware Advanced Audio Decoder 2 (FAAD2) 2.7 allows remote attackers to cause a denial of service (infinite loop and CPU consumption) via a crafted mp4 file.
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Analysis
by VulDB Data Team • 10/20/2019
The vulnerability identified as CVE-2017-9222 affects the Freeware Advanced Audio Decoder 2 version 2.7, specifically within the mp4ff_parse_tag function located in the common/mp4ff/mp4meta.c source file. This issue represents a critical denial of service vulnerability that can be exploited by remote attackers through the careful crafting of mp4 media files. The flaw manifests as an infinite loop condition that consumes excessive CPU resources, effectively rendering the affected system unable to process additional audio decoding requests. The vulnerability demonstrates a classic example of improper input validation where the decoder fails to properly handle malformed mp4 metadata structures, leading to predictable execution flow issues.
The technical root cause of this vulnerability lies in the mp4ff_parse_tag function's inadequate handling of malformed mp4 file structures during metadata parsing operations. When processing crafted mp4 files, the function enters an infinite loop due to insufficient boundary checks and recursive parsing logic that fails to properly terminate execution when encountering unexpected data patterns. This behavior aligns with CWE-835, which describes the weakness of infinite loops or infinite recursion in software implementations. The vulnerability operates at the application layer and can be triggered through standard mp4 file parsing operations, making it particularly dangerous as it requires no special privileges or complex attack vectors to exploit. The issue is classified as a resource exhaustion vulnerability since the infinite loop consumes CPU cycles continuously until manually terminated or system resources are depleted.
The operational impact of CVE-2017-9222 extends beyond simple service disruption to encompass broader system stability concerns for applications and services that rely on FAAD2 for audio processing. Systems utilizing this decoder for streaming audio content, media processing pipelines, or any application that accepts user-uploaded mp4 files become vulnerable to sustained denial of service attacks. The vulnerability can be exploited in various contexts including web applications, media servers, and content delivery networks that process mp4 files without proper input sanitization. Attackers can maintain prolonged resource consumption by simply providing a single maliciously crafted file, making this a particularly effective vector for persistent denial of service attacks. This vulnerability also aligns with ATT&CK technique T1499.004, which describes network denial of service attacks that consume system resources through malformed input processing.
Mitigation strategies for CVE-2017-9222 should focus on immediate software updates and input validation enhancements. The most effective solution involves upgrading to FAAD2 version 2.8 or later, where the parsing logic has been corrected to properly handle malformed mp4 structures and prevent infinite loop conditions. Organizations should implement comprehensive input validation measures that include file size limits, metadata structure validation, and timeout mechanisms for file processing operations. Additionally, deploying network-based intrusion detection systems that can identify suspicious file patterns and implementing proper sandboxing techniques for mp4 file processing can provide additional layers of protection. The vulnerability also highlights the importance of thorough code review processes and the implementation of automated testing procedures that include fuzzing techniques to identify similar parsing vulnerabilities in multimedia libraries. Security teams should also consider implementing monitoring systems that can detect unusual CPU consumption patterns that may indicate exploitation attempts, as this vulnerability can be used to create sustained resource exhaustion attacks against targeted systems.