CVE-2020-23904 in Speex
Summary
by MITRE • 11/11/2021
A stack buffer overflow in speexenc.c 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 • 08/04/2024
The vulnerability identified as CVE-2020-23904 represents a critical stack buffer overflow flaw within the Speex audio encoding library version 1.2. This issue specifically resides in the speexenc.c source file, which handles the encoding of audio data into the Speex format. The vulnerability manifests when the software processes maliciously crafted WAV files that contain malformed audio data structures. The flaw stems from inadequate input validation and bounds checking within the audio processing pipeline, where the application fails to properly verify the size and structure of incoming audio data before attempting to copy it into fixed-size stack buffers. This allows an attacker to manipulate the input data in such a way that it exceeds the allocated buffer space, leading to memory corruption and potential system instability.
The technical execution of this vulnerability follows a classic buffer overflow pattern where the attacker crafts a WAV file containing oversized or malformed audio headers that trigger the overflow condition during the encoding process. When the speexenc application attempts to process this crafted input, the malformed data causes the program to write beyond the boundaries of allocated stack memory regions. This memory corruption can result in program termination, segmentation faults, or in more severe cases, arbitrary code execution depending on the system configuration and memory layout. The vulnerability is particularly concerning because it operates at the input validation layer, meaning that any application or system utilizing the Speex library for audio processing could be susceptible to this attack vector. The flaw aligns with CWE-121 Stack-based Buffer Overflow, which specifically addresses buffer overflows occurring in stack memory regions due to insufficient bounds checking. This vulnerability falls under the ATT&CK technique T1499.004, which describes the use of resource exhaustion attacks, particularly denial of service through malformed input processing.
The operational impact of CVE-2020-23904 extends beyond simple denial of service conditions, as it represents a potential pathway for more sophisticated attacks within systems that process audio content. Applications that integrate the Speex library for voice communication, audio recording, or multimedia processing are at risk when handling untrusted WAV files. The vulnerability can be exploited in environments where users might encounter malicious audio files through email attachments, web downloads, or file sharing platforms. In enterprise settings, this could affect VoIP systems, audio conferencing applications, or any software that performs audio transcoding. The exploitation requires minimal technical expertise, making it particularly dangerous as it can be leveraged by attackers with limited knowledge of advanced exploit development techniques. Organizations relying on Speex-based applications should consider this vulnerability as part of their broader security posture assessment, particularly in environments where audio processing pipelines handle untrusted input from external sources. The impact is further amplified by the widespread adoption of Speex in various open source multimedia applications, potentially affecting numerous downstream systems that utilize this library.
Mitigation strategies for CVE-2020-23904 focus primarily on immediate software updates and input validation improvements. The most effective approach involves upgrading to a patched version of the Speex library where the buffer overflow has been addressed through proper bounds checking and input sanitization. System administrators should prioritize patch management for all applications utilizing Speex v1.2 or earlier versions, particularly those handling audio file processing from untrusted sources. Additional defensive measures include implementing strict input validation at multiple layers of the application stack, including the use of memory protection mechanisms such as stack canaries and address space layout randomization. Network-based mitigations could involve implementing content filtering for audio file types and establishing secure processing pipelines that isolate audio handling components from core application logic. Organizations should also consider implementing runtime monitoring to detect anomalous memory access patterns that might indicate exploitation attempts. The vulnerability highlights the importance of adhering to secure coding practices and conducting thorough code reviews for buffer management operations, particularly in legacy systems that may not have undergone modern security assessments. Regular security testing including fuzzing of input processing components should be integrated into development lifecycle processes to identify similar vulnerabilities before they can be exploited in production environments.