CVE-2020-23903 in Speex
Summary
by MITRE • 11/11/2021
A Divide by Zero vulnerability in the function static int read_samples of Speex v1.2 allows attackers to cause a denial of service (DoS) via a crafted WAV file.
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Analysis
by VulDB Data Team • 11/16/2021
The CVE-2020-23903 vulnerability represents a critical divide by zero error within the Speex v1.2 audio processing library, specifically within the static int read_samples function. This flaw manifests when the library processes maliciously crafted WAV files that contain malformed audio data structures designed to trigger arithmetic exceptions during decoding operations. The vulnerability exists at the intersection of audio format parsing and mathematical computation, where the software fails to properly validate input parameters before performing division operations. When an attacker crafts a WAV file with specific header values or audio sample configurations that result in a zero denominator during the read_samples function execution, the system experiences a program termination or crash, leading to a denial of service condition that affects applications relying on Speex for audio processing.
The technical implementation of this vulnerability stems from inadequate input validation mechanisms within the Speex library's audio sample reading functionality. The read_samples function, which is responsible for extracting and processing audio data from WAV containers, performs mathematical operations without verifying that divisor values remain non-zero during the decoding process. This failure to implement proper boundary checking and arithmetic validation creates an exploitable condition where crafted audio files can force the application into an undefined state. The vulnerability aligns with CWE-369, which categorizes divide-by-zero errors as a fundamental flaw in input validation and mathematical operation handling, particularly in systems processing multimedia content where malformed input is common. The flaw demonstrates poor defensive programming practices that allow malicious input to disrupt normal program execution flow.
The operational impact of CVE-2020-23903 extends beyond simple service disruption, as it can affect a wide range of applications and systems that utilize Speex for audio processing tasks. Applications such as VoIP systems, audio streaming platforms, and multimedia processing software that incorporate Speex v1.2 libraries become vulnerable to remote denial of service attacks when processing untrusted audio content. Attackers can exploit this vulnerability by simply providing a malicious WAV file to any system using the affected library, making the attack vector particularly dangerous due to its simplicity and low resource requirements. The vulnerability affects systems across multiple platforms including Windows, Linux, and mobile operating systems where Speex is integrated into audio processing pipelines, potentially creating widespread service disruption across various networked applications that depend on reliable audio processing capabilities. This DoS condition can be particularly problematic in mission-critical environments where continuous audio service availability is essential.
Mitigation strategies for CVE-2020-23903 require immediate attention from system administrators and software developers who utilize Speex v1.2 libraries. The primary remediation involves upgrading to Speex v1.2.1 or later versions where the divide by zero condition has been addressed through proper input validation and error handling mechanisms. Organizations should implement comprehensive patch management procedures to ensure all affected systems receive updates promptly, particularly in environments where audio processing is a core functionality. Additionally, deploying input sanitization measures at network boundaries and implementing proper file validation protocols can provide additional defense-in-depth layers. Security teams should consider implementing network monitoring to detect unusual patterns of audio file processing that might indicate exploitation attempts. The vulnerability also highlights the importance of adhering to secure coding practices such as those outlined in the ATT&CK framework's defense evasion techniques, where proper input validation and error handling should be considered fundamental security controls. Organizations should conduct thorough vulnerability assessments to identify all systems utilizing affected Speex versions and establish continuous monitoring procedures to prevent similar issues in other multimedia processing libraries.