CVE-2009-0772 in Firefox
Summary
by MITRE
The layout engine in Mozilla Firefox 2 and 3 before 3.0.7, Thunderbird before 2.0.0.21, and SeaMonkey 1.1.15 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via vectors related to nsCSSStyleSheet::GetOwnerNode, events, and garbage collection, which triggers memory corruption.
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Analysis
by VulDB Data Team • 08/30/2019
The vulnerability described in CVE-2009-0772 represents a critical memory corruption issue affecting Mozilla Firefox versions 2 and 3, Thunderbird versions prior to 2.0.0.21, and SeaMonkey 1.1.15. This flaw exists within the layout engine's handling of CSS stylesheet operations, specifically in the nsCSSStyleSheet::GetOwnerNode method which interacts with event processing and garbage collection mechanisms. The vulnerability demonstrates characteristics consistent with a use-after-free condition or buffer overflow that can be exploited through crafted web content to manipulate memory structures in ways that lead to system instability or unauthorized code execution.
The technical exploitation of this vulnerability occurs when malicious web content triggers the interaction between CSS stylesheet processing and JavaScript event handling within the browser's rendering engine. When the nsCSSStyleSheet::GetOwnerNode method processes certain CSS properties or event handlers, it interacts with memory that has already been freed during garbage collection cycles. This creates a scenario where an attacker can manipulate the memory layout to inject or redirect execution flow, potentially leading to arbitrary code execution. The vulnerability is particularly dangerous because it combines multiple attack vectors including CSS parsing, event handling, and memory management components, making it difficult to detect and prevent through traditional security measures.
The operational impact of this vulnerability extends beyond simple denial of service to include potential remote code execution capabilities that could allow attackers to compromise user systems completely. When exploited successfully, the memory corruption can result in browser crashes, system instability, or more severe consequences including full system compromise. The vulnerability affects widely deployed software including Firefox 2 and 3, which were among the most popular web browsers at the time of discovery, making the potential attack surface extremely broad. Organizations running these vulnerable versions face significant risk of targeted attacks and automated exploitation attempts.
Security professionals should prioritize immediate patching of all affected software versions to prevent exploitation. The recommended mitigation strategy includes updating to Firefox 3.0.7, Thunderbird 2.0.0.21, and SeaMonkey 1.1.16 or later versions that contain the necessary fixes. Additionally, network administrators should implement web content filtering and monitoring solutions to detect and block potentially malicious content that might trigger this vulnerability. Organizations should also consider implementing browser hardening measures such as disabling unnecessary JavaScript features, restricting access to potentially dangerous CSS properties, and maintaining up-to-date intrusion detection systems to monitor for exploitation attempts. This vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and represents a classic example of how complex interactions between memory management and parsing components can create dangerous security flaws that require comprehensive remediation approaches.
The attack pattern for this vulnerability follows typical remote code execution vectors as defined by the attack framework, where an attacker crafts malicious web content that when loaded in a vulnerable browser triggers the memory corruption. The exploitation process typically involves creating carefully constructed CSS rules and JavaScript events that cause the browser to access freed memory during garbage collection cycles, leading to either crash conditions or code execution. This vulnerability demonstrates the importance of proper memory management in browser engines and the critical need for thorough testing of complex interactions between different software components. The remediation process requires not only patching but also comprehensive security auditing of similar memory handling patterns within the browser's codebase to prevent similar issues from emerging in the future.