CVE-2015-4506 in Firefox
Summary
by MITRE
Buffer overflow in the vp9_init_context_buffers function in libvpx, as used in Mozilla Firefox before 41.0 and Firefox ESR 38.x before 38.3, allows remote attackers to execute arbitrary code via a crafted VP9 file.
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Analysis
by VulDB Data Team • 10/22/2024
The vulnerability identified as CVE-2015-4506 represents a critical buffer overflow condition within the libvpx library's vp9_init_context_buffers function. This flaw exists in the VP9 video codec implementation that was integrated into Mozilla Firefox browsers prior to version 41.0 and Firefox ESR 38.x prior to version 38.3. The vulnerability stems from inadequate input validation and memory management within the video decoding process, specifically when handling VP9 encoded media content. Attackers can exploit this weakness by crafting malicious VP9 video files that trigger the buffer overflow during the initialization of context buffers, potentially leading to arbitrary code execution on affected systems. The flaw demonstrates a classic software security issue where insufficient bounds checking allows malicious data to overwrite adjacent memory regions, creating opportunities for code injection attacks.
The technical implementation of this vulnerability involves the vp9_init_context_buffers function failing to properly validate the size and structure of incoming VP9 video data before allocating memory for context buffers. When Firefox processes a crafted VP9 file, the malicious input causes the function to write beyond the allocated buffer boundaries, corrupting adjacent memory locations. This type of buffer overflow is classified as a CWE-121 stack-based buffer overflow, where the overflow occurs in stack memory allocated for local variables. The vulnerability operates at the intersection of multimedia processing and memory safety, making it particularly dangerous as it can be triggered through standard web browsing activities involving video content. The attack vector is remote and requires no user interaction beyond visiting a malicious website or opening a malicious email attachment containing the crafted VP9 file.
The operational impact of CVE-2015-4506 extends beyond simple code execution, as it provides attackers with a powerful means of compromising user systems. Successful exploitation can lead to complete system compromise, allowing threat actors to install malware, steal sensitive data, or establish persistent backdoors. The vulnerability affects a widely used browser application, making it particularly attractive to cybercriminals who can leverage it in mass phishing campaigns or drive-by download attacks. The attack surface is broad since VP9 video support is increasingly common across web platforms, and the vulnerability can be triggered through various means including embedded video content, streaming media, or file attachments. Organizations using affected Firefox versions face significant risk, particularly those with users who frequently access untrusted websites or receive email communications from potentially compromised sources.
Mitigation strategies for CVE-2015-4506 focus primarily on immediate software updates and browser patching to address the underlying buffer overflow condition. Users and organizations should prioritize upgrading to Firefox versions 41.0 or later, or Firefox ESR 38.3 and later, which contain the necessary fixes for the vp9_init_context_buffers function. Additional protective measures include implementing web content filtering solutions that can block or sandbox VP9 video content, disabling automatic media playback in browsers, and deploying intrusion detection systems that monitor for exploitation attempts. Security professionals should also consider network-level protections such as web application firewalls that can detect and prevent malicious VP9 file delivery. The remediation process should include comprehensive testing of patched browsers to ensure that the vulnerability is fully resolved without introducing regressions in video playback functionality. Organizations should also conduct security assessments to verify that all affected systems have been properly updated and that no legacy installations remain vulnerable to this specific buffer overflow exploitation technique.