CVE-2010-2762 in Firefox
Summary
by MITRE
The XPCSafeJSObjectWrapper class in the SafeJSObjectWrapper (aka SJOW) implementation in Mozilla Firefox 3.6.x before 3.6.9 and Thunderbird 3.1.x before 3.1.3 does not properly restrict objects at the end of scope chains, which allows remote attackers to execute arbitrary JavaScript code with chrome privileges via vectors related to a chrome privileged object and a chain ending in an outer object.
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Analysis
by VulDB Data Team • 09/24/2021
The vulnerability described in CVE-2010-2762 represents a critical security flaw in the JavaScript engine implementation of Mozilla Firefox and Thunderbird browsers. This issue resides within the XPCSafeJSObjectWrapper class, which is part of the SafeJSObjectWrapper (SJOW) mechanism designed to provide security boundaries between privileged chrome code and untrusted web content. The vulnerability specifically targets the scope chain handling mechanism that governs how JavaScript objects are accessed and manipulated within the browser's execution environment. When objects reach the end of their scope chain, the implementation fails to properly validate or restrict access to chrome privileged objects, creating a potential attack vector that could be exploited by malicious actors.
The technical flaw manifests in the improper handling of scope chains where the SafeJSObjectWrapper does not adequately enforce security boundaries when objects are accessed at the termination point of scope chains. This allows attackers to construct specific JavaScript code sequences that can traverse the scope chain and gain access to chrome privileged objects that should normally be restricted from web content. The vulnerability specifically affects versions of Firefox 3.6.x prior to 3.6.9 and Thunderbird 3.1.x prior to 3.1.3, indicating that this was a widespread issue affecting the core JavaScript engine implementation across these browser versions. The attack requires an attacker to craft a malicious script that can manipulate the scope chain in such a way that it ends with a chrome privileged object, effectively bypassing the security restrictions that should normally prevent web content from executing privileged operations.
The operational impact of this vulnerability is severe as it allows remote attackers to execute arbitrary JavaScript code with chrome privileges, which represents a significant escalation from regular web content execution to privileged system-level operations. Chrome privileges provide access to the browser's internal components, system resources, and potentially sensitive user data, making this a critical security concern. Attackers could leverage this vulnerability to perform actions such as reading and modifying browser configuration files, accessing user credentials stored in the browser, executing arbitrary system commands, or even installing malware directly through the browser. The vulnerability essentially allows a sandbox escape, where web-based attacks can break out of the normal security boundaries that protect the browser from malicious code execution, potentially leading to complete system compromise.
The exploitation of this vulnerability aligns with several ATT&CK framework techniques including privilege escalation and sandbox evasion, where attackers leverage implementation flaws to gain elevated privileges. From a CWE perspective, this vulnerability maps to CWE-264, which deals with permissions, privileges, and access controls, specifically in the context of improper restriction of operations within a scope. The vulnerability also relates to CWE-119, which addresses weaknesses in memory management, particularly in how objects are accessed and validated at scope chain boundaries. Organizations should immediately apply the security patches released by Mozilla for Firefox 3.6.9 and Thunderbird 3.1.3 to address this vulnerability. Additionally, network administrators should consider implementing web application firewalls and content filtering solutions to detect and block potentially malicious JavaScript code that might attempt to exploit this or similar vulnerabilities. Regular security updates and monitoring for other related vulnerabilities in the browser's JavaScript engine implementation are essential to maintaining a secure browsing environment.