CVE-2015-0806 in Firefox
Summary
by MITRE
The Off Main Thread Compositing (OMTC) implementation in Mozilla Firefox before 37.0 attempts to use memset for a memory region of negative length 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) via vectors that trigger rendering of 2D graphics content.
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Analysis
by VulDB Data Team • 05/02/2022
The vulnerability identified as CVE-2015-0806 represents a critical memory corruption flaw within Mozilla Firefox's Off Main Thread Compositing (OMTC) subsystem. This issue specifically affects Firefox versions prior to 37.0 and stems from improper handling of memory allocation during graphics rendering operations. The flaw manifests when the OMTC implementation attempts to utilize the memset function on a memory region specified with a negative length parameter, creating a dangerous condition that can be exploited by remote attackers.
The technical exploitation occurs through the mozilla::layers::BufferTextureClient::AllocateForSurface function, which serves as a critical component in Firefox's graphics rendering pipeline. When processing 2D graphics content, the system calculates memory requirements that can result in negative values due to flawed boundary calculations or input validation issues. The memset function, when provided with a negative length parameter, exhibits undefined behavior that can lead to memory corruption patterns. This corruption can manifest in various ways including stack smashing, heap corruption, or arbitrary memory overwrite operations that compromise the browser's memory integrity.
The operational impact of this vulnerability extends beyond simple denial of service conditions to encompass full arbitrary code execution capabilities. Attackers can leverage this flaw by crafting malicious web content that triggers the specific rendering path containing the vulnerable memset call. The memory corruption allows for precise control over memory layout and can potentially enable privilege escalation attacks. This vulnerability directly maps to CWE-122, which describes "Heap-based Buffer Overflow" conditions, and aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: JavaScript", as the attack vector typically involves malicious javascript code that triggers the vulnerable rendering path.
The exploitation process requires attackers to construct web pages containing specific 2D graphics operations that force Firefox into the problematic code path. This typically involves complex canvas operations or SVG content that interacts with the OMTC subsystem. The vulnerability demonstrates a classic buffer management error where the system fails to validate memory allocation parameters before passing them to memory manipulation functions. Security researchers have noted that this flaw was particularly dangerous because it could be triggered through standard web browsing activities without requiring user interaction beyond visiting malicious websites.
Mitigation strategies for CVE-2015-0806 primarily focus on upgrading to Firefox version 37.0 or later, where the underlying memory handling has been corrected. System administrators should implement comprehensive patch management procedures to ensure all affected browsers are updated promptly. Additional protective measures include enabling security features such as Address Space Layout Randomization (ASLR) and Data Execution Prevention (DEP) where available. Network-level protections such as web application firewalls and content filtering systems can provide additional layers of defense against exploitation attempts. The vulnerability highlights the importance of proper input validation in graphics rendering systems and underscores the need for rigorous memory safety practices in browser implementations. Organizations should conduct regular security assessments to identify similar memory corruption patterns in their browser environments and ensure that all third-party graphics libraries and rendering components are kept current with security patches.