CVE-2008-2009 in libvorbis
Summary
by MITRE
Xiph.org libvorbis before 1.0 does not properly check for underpopulated Huffman trees, which allows remote attackers to cause a denial of service (crash) via a crafted OGG file that triggers memory corruption during execution of the _make_decode_tree function.
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Analysis
by VulDB Data Team • 08/01/2021
The vulnerability described in CVE-2008-2009 represents a critical memory corruption issue within the libvorbis library version 1.0 and earlier, which serves as a foundational component for audio processing in numerous multimedia applications and systems. This flaw specifically manifests in the handling of Huffman trees during the decoding process of OGG audio files, where the library fails to properly validate the structure and completeness of these essential data structures. The issue stems from inadequate input validation mechanisms that should have verified the integrity of Huffman tree construction before proceeding with decompression operations. When an attacker crafts a malicious OGG file containing underpopulated Huffman trees, the library's internal functions become vulnerable to exploitation, leading to unpredictable memory behavior and system instability.
The technical exploitation of this vulnerability occurs within the _make_decode_tree function, which is responsible for constructing the decoding tree structure necessary for decompressing Vorbis audio data. This function does not adequately validate whether the Huffman tree has sufficient nodes and proper connectivity to support the decoding process. When encountering underpopulated trees, the function attempts to access memory locations that may be uninitialized or improperly allocated, resulting in memory corruption that manifests as program crashes or system hangs. The vulnerability specifically targets the memory management aspects of the Huffman decoding algorithm, creating conditions where the program's execution flow becomes unpredictable and potentially exploitable. This type of flaw falls under the CWE-125 vulnerability category, which encompasses out-of-bounds read conditions that can lead to memory corruption and arbitrary code execution.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it can be leveraged by remote attackers to disrupt services across a wide range of applications that utilize libvorbis for audio processing. Systems including web browsers, media players, content management systems, and multimedia frameworks that depend on this library become susceptible to crashes when processing maliciously crafted audio files. The vulnerability affects not only individual user systems but also server environments where automated processing of user-uploaded content could lead to widespread service disruption. Attackers can exploit this weakness by simply embedding the crafted OGG file in web content or sending it as an attachment, making the attack vector particularly dangerous in environments where users can upload multimedia content. This vulnerability aligns with ATT&CK technique T1499.004, which involves network denial of service attacks through exploitation of software vulnerabilities in multimedia processing components.
Mitigation strategies for CVE-2008-2009 primarily focus on upgrading to libvorbis version 1.0 or later, where the underlying Huffman tree validation has been strengthened to prevent underpopulated tree structures from causing memory corruption. Organizations should implement comprehensive patch management procedures to ensure all systems utilizing libvorbis are updated to versions that contain the necessary security fixes. Additionally, input validation measures should be implemented at application layers that process OGG files, including file format verification and size limitations to prevent exploitation. Network security controls such as content filtering and sandboxing mechanisms can provide additional protection by preventing potentially malicious OGG files from reaching vulnerable applications. System administrators should also consider implementing monitoring and alerting mechanisms to detect unusual patterns in audio processing that might indicate exploitation attempts, particularly in environments where user-generated content is processed automatically. The vulnerability serves as a reminder of the importance of robust input validation in cryptographic and decompression algorithms, emphasizing the need for defensive programming practices that prevent memory corruption through proper boundary checking and resource management.