CVE-2008-5036 in VLC Media Player
Summary
by MITRE
Stack-based buffer overflow in VideoLAN VLC media player 0.9.x before 0.9.6 might allow user-assisted attackers to execute arbitrary code via an an invalid RealText (rt) subtitle file, related to the ParseRealText function in modules/demux/subtitle.c. NOTE: this issue was SPLIT from CVE-2008-5032 on 20081110.
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Analysis
by VulDB Data Team • 11/10/2024
The vulnerability CVE-2008-5036 represents a critical stack-based buffer overflow in VideoLAN VLC media player version 0.9.x prior to 0.9.6, specifically within the RealText subtitle parsing functionality. This flaw resides in the ParseRealText function located in the modules/demux/subtitle.c source file, where improper input validation leads to memory corruption during subtitle file processing. The vulnerability is classified as user-assisted, meaning an attacker must entice a victim to open a maliciously crafted RealText (.rt) subtitle file for the exploit to succeed, making it particularly dangerous in scenarios where users might encounter such files through email attachments, web downloads, or shared media collections.
The technical implementation of this buffer overflow stems from inadequate bounds checking within the subtitle parsing routine, where the application fails to properly validate the length of data read from RealText files before copying it into fixed-size stack buffers. When processing malformed subtitle data, the application writes more data than the allocated buffer space can accommodate, causing stack corruption that can overwrite adjacent memory locations including return addresses and function pointers. This memory corruption creates opportunities for arbitrary code execution, as attackers can manipulate the overwritten memory locations to redirect program execution flow to malicious code. The vulnerability directly maps to CWE-121 Stack-based Buffer Overflow, which is categorized under the weakness type for buffer overflows occurring in stack memory regions, and aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter using Windows Command Shell.
The operational impact of this vulnerability extends beyond simple code execution, as it can enable attackers to gain full control over the affected system running the vulnerable VLC player. When a victim opens a malicious subtitle file, the attacker can potentially execute arbitrary commands with the privileges of the user running VLC, which typically runs with standard user permissions but could potentially escalate privileges depending on system configuration. The vulnerability affects a wide range of operating systems including Windows, Linux, and macOS where VLC is installed, making it particularly dangerous in enterprise environments where media players are frequently used for presentations, training materials, or entertainment content. The issue was originally grouped with CVE-2008-5032 but was later split to better isolate this specific buffer overflow component, indicating the severity and complexity of the underlying vulnerability.
Mitigation strategies for CVE-2008-5036 primarily focus on immediate patching and system hardening measures. Users should immediately upgrade to VLC media player version 0.9.6 or later, which contains the necessary fixes for the buffer overflow vulnerability. Organizations should implement strict file validation policies for media content, particularly when dealing with third-party or untrusted sources, and consider disabling automatic subtitle loading or implementing sandboxing techniques for media player applications. Network administrators should monitor for suspicious file downloads and implement content filtering solutions to prevent users from accessing potentially malicious subtitle files. Additionally, system administrators should consider implementing application whitelisting policies that restrict execution of unauthorized media player versions, and regular security audits should verify that all systems have been updated to patched versions. The vulnerability demonstrates the importance of proper input validation in multimedia processing applications and highlights the need for robust memory safety practices in media player development.