CVE-2015-0805 in Firefox
Summary
by MITRE
The Off Main Thread Compositing (OMTC) implementation in Mozilla Firefox before 37.0 makes an incorrect memset call during interaction with the mozilla::layers::BufferTextureClient::AllocateForSurface function, which allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption and application crash) via vectors that trigger rendering of 2D graphics content.
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Analysis
by VulDB Data Team • 05/02/2022
The vulnerability described in CVE-2015-0805 resides within the Off Main Thread Compositing (OMTC) subsystem of Mozilla Firefox versions prior to 37.0. This feature enables Firefox to perform compositing operations on separate threads, improving performance by offloading rendering tasks from the main browser thread. The flaw manifests specifically within the mozilla::layers::BufferTextureClient::AllocateForSurface function where an incorrect memset call is executed during the handling of 2D graphics content rendering. This memory management error represents a critical security weakness that can be exploited by remote attackers through carefully crafted web content.
The technical nature of this vulnerability stems from improper memory initialization during the allocation process for texture clients used in graphics rendering. When Firefox processes 2D graphics content, the OMTC implementation attempts to clear memory using memset with incorrect parameters, leading to memory corruption that can be leveraged for arbitrary code execution. The flaw occurs because the memset function receives invalid size parameters or incorrect memory addresses, causing the application to write beyond allocated memory boundaries or corrupt adjacent memory regions. This type of memory corruption vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-122, which covers stack-based buffer overflow scenarios.
The operational impact of this vulnerability extends beyond simple application crashes to potentially enable full remote code execution on affected systems. Attackers can craft malicious web pages containing 2D graphics content that, when rendered by the vulnerable Firefox version, triggers the flawed memset call and subsequently executes attacker-controlled code with the privileges of the browser process. This represents a severe security risk as it allows for complete system compromise without requiring user interaction beyond visiting a malicious website. The vulnerability affects the browser's rendering engine and can be exploited through various vectors including web pages, embedded images, or canvas elements that trigger the problematic graphics rendering path.
From a threat modeling perspective, this vulnerability maps to multiple ATT&CK techniques including T1059 for command and scripting interpreter usage and T1068 for exploit for privilege escalation. The attack surface is broad as it affects any user visiting compromised websites or clicking on malicious links that render 2D graphics content. Security professionals should note that this vulnerability demonstrates the complexity of modern browser security where features designed to improve performance can introduce critical security flaws. The issue highlights the importance of thorough code review for memory management operations, particularly in multi-threaded environments where race conditions and improper memory handling can lead to severe security consequences.
Mitigation strategies for this vulnerability include immediate upgrade to Firefox version 37.0 or later where the memset call has been corrected and the memory management issue resolved. Organizations should also implement network-based security controls such as web application firewalls and content filtering solutions to block access to known malicious domains. Additionally, browser hardening techniques including disabling unnecessary graphics features and implementing strict security policies can reduce the attack surface. The fix implemented in Firefox 37.0 addresses the root cause by correcting the memset parameters and ensuring proper memory initialization during texture client allocation, thereby preventing the memory corruption that enabled remote code execution.