CVE-2017-8374 in MAD libmad
Summary
by MITRE
The mad_bit_skip function in bit.c in Underbit MAD libmad 0.15.1b allows remote attackers to cause a denial of service (heap-based buffer over-read and application crash) via a crafted audio file.
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Analysis
by VulDB Data Team • 12/02/2022
The vulnerability identified as CVE-2017-8374 resides within the mad_bit_skip function in the bit.c component of Underbit MAD libmad version 0.15.1b, representing a critical heap-based buffer over-read condition that can be exploited remotely to trigger denial of service. This flaw specifically manifests when processing maliciously crafted audio files, enabling attackers to manipulate memory access patterns that exceed allocated buffer boundaries. The issue stems from insufficient input validation and boundary checking within the bitstream parsing logic that handles MPEG audio decoding operations.
The technical implementation of this vulnerability involves the mad_bit_skip function failing to properly validate bitstream positions before attempting to skip bits within the audio data. When confronted with specially constructed audio files containing malformed bitstream data, the function executes an over-read operation that accesses memory locations beyond the intended buffer limits. This heap-based buffer over-read occurs because the implementation does not adequately verify that bit skipping operations remain within allocated memory boundaries, allowing arbitrary memory access patterns that can cause application crashes or unpredictable behavior. The vulnerability falls under CWE-125, which specifically addresses out-of-bounds read conditions, and represents a classic example of improper input validation leading to memory corruption.
From an operational perspective, this vulnerability presents significant risk to systems that process or decode MPEG audio files using the affected libmad library. Attackers can remotely exploit this flaw by delivering malicious audio files to systems running applications that utilize libmad for audio processing, potentially causing service disruption through application crashes. The impact extends beyond simple denial of service as the memory corruption can lead to unpredictable application behavior, data loss, or even potential privilege escalation in certain scenarios. Systems particularly vulnerable include media servers, streaming applications, audio processing software, and any applications that handle user-uploaded audio content without proper sanitization.
The exploitation of CVE-2017-8374 aligns with ATT&CK technique T1203, which involves exploiting weaknesses in software to achieve remote code execution or denial of service. This vulnerability represents a common attack vector in media processing applications where input sanitization is insufficient, making it particularly dangerous in environments where users can upload audio files. Mitigation strategies include applying the vendor-provided patches that address the buffer over-read condition in the bit.c file, implementing proper input validation for audio file processing, and deploying network segmentation to limit exposure. Additionally, organizations should consider implementing application sandboxing and memory protection mechanisms to contain potential exploitation attempts and reduce the attack surface. The vulnerability demonstrates the critical importance of proper memory management and input validation in multimedia processing libraries, particularly those handling untrusted user data.