CVE-2014-8632 in Firefox
Summary
by MITRE
The structured-clone implementation in Mozilla Firefox before 34.0 and SeaMonkey before 2.31 does not properly interact with XrayWrapper property filtering, which allows remote attackers to bypass intended DOM object restrictions by leveraging property availability after XrayWrapper removal.
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Analysis
by VulDB Data Team • 03/02/2022
The vulnerability identified as CVE-2014-8632 represents a critical security flaw in the structured-clone implementation within Mozilla Firefox versions prior to 34.0 and SeaMonkey versions prior to 2.31. This issue stems from improper interaction between the structured-clone mechanism and XrayWrapper property filtering systems, creating a pathway for remote attackers to circumvent intended security restrictions. The structured-clone API is designed to enable deep copying of JavaScript objects, including DOM objects, while maintaining proper security boundaries and access controls. However, the flaw manifests when XrayWrapper objects are removed from the system, leaving behind properties that should have been filtered out during the cloning process.
The technical exploitation of this vulnerability occurs through a sophisticated bypass mechanism that leverages the timing and interaction between two distinct security components. XrayWrapper serves as a security layer that filters access to DOM objects by wrapping them and controlling property access, ensuring that malicious code cannot directly access sensitive properties. When the structured-clone operation processes objects that have been wrapped by XrayWrapper, the implementation fails to properly account for the removal of these wrappers, allowing certain properties to remain accessible in the cloned object that should have been filtered out. This creates a scenario where attackers can extract information or manipulate objects that should have been restricted, effectively breaking the security model that protects against cross-site scripting and other malicious activities.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables attackers to potentially manipulate DOM objects in ways that could lead to more severe security consequences. Attackers can craft malicious web content that, when executed in vulnerable browsers, allows them to access properties and methods that should be restricted to legitimate web applications. This bypass capability undermines the fundamental security architecture of modern web browsers, which relies on strict object access controls to prevent malicious code from exploiting legitimate browser functionality. The vulnerability is particularly concerning because it operates at the core of browser security mechanisms, potentially allowing attackers to escalate privileges or perform actions that should be impossible within the browser's security model.
Mitigation strategies for CVE-2014-8632 require immediate browser updates to versions that contain the patched implementation of the structured-clone functionality. Users should upgrade to Firefox 34.0 or later and SeaMonkey 2.31 or later, where the interaction between XrayWrapper and structured-clone has been properly addressed. Security researchers have identified this issue as aligning with CWE-284, which deals with inadequate access control, and it demonstrates characteristics consistent with ATT&CK technique T1059.007 for JavaScript execution and T1071.001 for application layer protocol usage. Organizations should implement comprehensive patch management processes to ensure all affected systems receive updates promptly, as this vulnerability can be exploited through various attack vectors including malicious websites, phishing campaigns, and compromised web applications that leverage the browser's scripting capabilities to execute the exploit code.