CVE-2017-9870 in LAME
Summary
by MITRE
The III_i_stereo function in layer3.c in mpglib, as used in libmpgdecoder.a in LAME 3.99.5 and other products, allows remote attackers to cause a denial of service (buffer over-read and application crash) via a crafted audio file.
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Analysis
by VulDB Data Team • 10/20/2019
The vulnerability identified as CVE-2017-9870 resides within the mpglib library component of LAME 3.99.5 and other software products that utilize libmpgdecoder.a for audio decoding operations. This issue specifically affects the III_i_stereo function located in the layer3.c file, which is responsible for processing stereo audio data during MPEG audio decoding. The flaw represents a classic buffer over-read condition that occurs when the function processes malformed audio files containing specially crafted data structures. The vulnerability manifests when the decoder attempts to read beyond the allocated memory boundaries while handling stereo channel information in MPEG layer 3 audio streams, creating a scenario where arbitrary memory access occurs beyond the intended buffer limits.
The technical implementation of this vulnerability involves the improper validation of input data within the stereo processing routine. When a maliciously constructed audio file is processed, the III_i_stereo function fails to properly bounds-check array accesses or validate the expected structure of stereo channel data. This allows an attacker to craft audio files with malformed metadata or channel information that causes the decoder to attempt reading memory locations that are outside the allocated buffer space. The over-read condition typically results in memory corruption that leads to application instability and ultimately causes the target application to crash or become unresponsive. This behavior aligns with CWE-129, which describes improper validation of array indices, and specifically relates to the broader category of buffer over-read vulnerabilities that are commonly exploited in multimedia processing applications.
The operational impact of CVE-2017-9870 extends beyond simple denial of service to potentially compromise system availability in environments where audio processing applications are critical to operations. Attackers can exploit this vulnerability remotely by delivering malicious audio files through various attack vectors such as web downloads, email attachments, or streaming services that utilize the affected library. The vulnerability affects a wide range of applications that depend on mpglib for audio decoding, including media players, audio processing tools, and streaming services. From an attacker's perspective, this represents a low-effort, high-impact vector for causing service disruption, as the exploit requires only the creation of a specially crafted audio file that can be distributed through standard channels. The vulnerability also maps to ATT&CK technique T1203, which involves the use of malicious files to cause system instability, and T1499.004, which covers network denial of service through resource exhaustion or application crashes.
Mitigation strategies for this vulnerability should focus on both immediate patching and defensive programming practices. The primary solution involves updating to patched versions of LAME and affected software products that contain fixes for the buffer over-read condition in the III_i_stereo function. Organizations should also implement input validation measures that include strict bounds checking for audio file processing, particularly for stereo channel data in MPEG layer 3 streams. Additional defensive measures include sandboxing audio processing applications, implementing network-based filtering to prevent malicious audio files from reaching end-user systems, and deploying intrusion detection systems that can identify suspicious audio file patterns. The vulnerability demonstrates the importance of proper memory management and bounds checking in multimedia libraries, particularly those handling user-provided content, and underscores the need for comprehensive security testing of audio processing components. Security teams should also consider implementing automated scanning for vulnerable libraries and establishing incident response procedures for handling audio-based denial of service attacks.