CVE-2017-9218 in Freeware Advanced Audio Decoder
Summary
by MITRE
The mp4ff_read_stsd function in common/mp4ff/mp4atom.c in Freeware Advanced Audio Decoder 2 (FAAD2) 2.7 allows remote attackers to cause a denial of service (invalid memory read and application crash) via a crafted mp4 file.
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Analysis
by VulDB Data Team • 10/20/2019
The vulnerability identified as CVE-2017-9218 resides within the Freeware Advanced Audio Decoder 2 version 2.7, specifically in the mp4ff_read_stsd function located in the common/mp4ff/mp4atom.c source file. This flaw represents a classic buffer over-read condition that occurs when processing malformed mp4 media files, making it a significant concern for systems that rely on FAAD2 for audio decoding operations. The vulnerability is classified under CWE-125 as an out-of-bounds read, which directly impacts the memory safety of the affected application.
The technical implementation of this vulnerability stems from insufficient input validation within the mp4ff_read_stsd function, which processes sample description atoms in mp4 containers. When a crafted mp4 file contains malformed or maliciously constructed data within the stsd atom structure, the function fails to properly bounds-check array accesses before reading memory locations. This improper validation allows attackers to construct specially formatted mp4 files that trigger invalid memory reads during the decoding process, ultimately leading to application crashes and denial of service conditions. The vulnerability demonstrates characteristics consistent with ATT&CK technique T1203 - Exploitation for Client Execution, where malicious input is used to compromise application stability.
The operational impact of CVE-2017-9218 extends beyond simple denial of service, as it can be exploited in various attack scenarios including web-based media processing systems, mobile applications, and media servers that utilize FAAD2 for audio decoding. Systems running vulnerable versions of FAAD2 are particularly at risk when processing untrusted mp4 content from external sources, such as user-uploaded media files in web applications or media streaming services. The vulnerability's remote exploitability means that attackers can trigger the condition without physical access to the target system, making it a critical concern for networked applications. This flaw can be leveraged in broader attack chains where initial compromise leads to more severe consequences through additional exploitation vectors.
Mitigation strategies for CVE-2017-9218 should prioritize immediate patching of affected FAAD2 installations to version 2.8 or later, where the vulnerability has been addressed through proper bounds checking and input validation. Organizations should implement strict file validation procedures for all mp4 content processing, including signature verification and format compliance checks before decoding operations. Network-based defenses can include content filtering mechanisms that identify and block suspicious mp4 file patterns, while application-level protections should enforce memory safety practices such as stack canaries and address space layout randomization. Additionally, system administrators should consider implementing monitoring solutions to detect unusual application crash patterns that may indicate exploitation attempts. The vulnerability underscores the importance of maintaining up-to-date media processing libraries and implementing defense-in-depth strategies to prevent exploitation of similar memory safety issues in multimedia applications.