CVE-2012-4208 in Firefox
Summary
by MITRE
The XrayWrapper implementation in Mozilla Firefox before 17.0, Thunderbird before 17.0, and SeaMonkey before 2.14 does not consider the compartment during property filtering, which allows remote attackers to bypass intended chrome-only restrictions on reading DOM object properties via a crafted web site.
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Analysis
by VulDB Data Team • 04/19/2021
The vulnerability identified as CVE-2012-4208 represents a critical security flaw in the XrayWrapper implementation within Mozilla Firefox, Thunderbird, and SeaMonkey browsers. This issue stems from the improper handling of compartmentalization principles during property filtering operations, creating a significant bypass mechanism that undermines the browser's security model. The flaw specifically affects versions prior to Firefox 17.0, Thunderbird 17.0, and SeaMonkey 2.14, leaving millions of users exposed to potential exploitation.
The technical root cause lies in the XrayWrapper's failure to properly enforce compartment boundaries when filtering object properties. In web browser security architectures, compartments serve as critical isolation mechanisms that separate privileged chrome code from untrusted web content. The XrayWrapper is designed to mediate access between these compartments, ensuring that web pages cannot directly access privileged chrome objects. However, this implementation flaw allows malicious actors to craft specific web pages that can bypass these protective measures by exploiting the inconsistent handling of property filtering across different compartments.
This vulnerability operates under the attack pattern described in the ATT&CK framework as a privilege escalation technique, specifically leveraging browser sandbox bypass mechanisms. The flaw enables remote attackers to access DOM object properties that should be restricted to chrome-level code only, effectively allowing them to read sensitive information that should remain protected. The impact extends beyond simple information disclosure, as it undermines the fundamental security boundaries that separate user content from browser internals.
The operational consequences of this vulnerability are severe and far-reaching, as it provides attackers with unauthorized access to privileged browser objects that contain sensitive data and functionality. This access can be leveraged to extract user credentials, manipulate browser behavior, or gain additional footholds within the victim's system. The vulnerability's classification aligns with CWE-284, which addresses inadequate access control mechanisms, and represents a failure in proper privilege management within the browser's security architecture.
Organizations and users must immediately upgrade to affected browser versions that contain the patched XrayWrapper implementation, as the vulnerability cannot be effectively mitigated through configuration changes or workarounds. The patch addresses the core compartmentalization issue by ensuring that property filtering operations properly consider compartment boundaries, thereby restoring the intended security model. Security teams should prioritize this update as a critical remediation step, as the vulnerability represents a significant risk to user privacy and system integrity. Additionally, network administrators should monitor for exploitation attempts and consider implementing additional security controls to detect and prevent malicious web content delivery that might attempt to leverage this flaw.