CVE-2017-9871 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 (stack-based buffer overflow and application crash) or possibly have unspecified other impact via a crafted audio file.
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Analysis
by VulDB Data Team • 10/20/2019
The vulnerability identified as CVE-2017-9871 represents a critical stack-based buffer overflow flaw within the mpglib library component of LAME 3.99.5 and related software products. This issue manifests specifically within the III_i_stereo function located in the layer3.c file, which processes MPEG audio layer III decoding operations. The vulnerability arises from inadequate input validation and boundary checking when handling specially crafted audio files that exploit the stereo processing functionality of the MPEG decoding algorithm. The flaw falls under the CWE-121 category of stack-based buffer overflow, where attacker-controlled data exceeds the allocated buffer space on the stack, potentially corrupting adjacent memory locations and causing unpredictable behavior.
The technical exploitation of this vulnerability occurs when an attacker provides a maliciously constructed audio file that triggers the III_i_stereo function with oversized or malformed data parameters. During the execution of this function, the mpglib library fails to properly validate the size of stereo processing data before copying it into fixed-size stack buffers. This allows an attacker to overwrite adjacent stack memory, potentially leading to application crashes, denial of service conditions, or in more severe cases, arbitrary code execution depending on memory layout and exploitation circumstances. The vulnerability demonstrates characteristics consistent with the ATT&CK technique T1203, where adversaries leverage buffer overflow conditions to compromise system integrity.
The operational impact of CVE-2017-9871 extends beyond simple denial of service scenarios, as it represents a potential pathway for more sophisticated attacks within systems that process audio files through vulnerable libraries. Applications utilizing LAME 3.99.5 or affected versions of mpglib become susceptible to remote exploitation, particularly in environments where users can upload or stream audio content. The vulnerability affects not only the direct users of LAME but also any software products that incorporate this library, creating a wide attack surface across various multimedia applications, media servers, and content processing systems. Organizations deploying software that relies on this library must consider the potential for remote code execution if the application stack is not properly hardened against buffer overflow conditions.
Mitigation strategies for CVE-2017-9871 should prioritize immediate software updates to versions that contain patches addressing the buffer overflow condition in the III_i_stereo function. System administrators should implement input validation controls that sanitize audio file inputs before processing, particularly focusing on MPEG audio files that may trigger the vulnerable code path. Additionally, memory protection mechanisms such as stack canaries, address space layout randomization, and non-executable stack protections should be enabled to reduce the exploitability of any remaining vulnerabilities. Organizations should also consider implementing network segmentation and access controls to limit exposure of vulnerable applications to untrusted network traffic, while maintaining regular vulnerability assessments to identify and remediate similar issues in their software supply chain. The fix typically involves implementing proper bounds checking and input validation within the stereo processing function to prevent buffer overflows while maintaining the intended audio processing functionality.