CVE-2012-4205 in Firefox
Summary
by MITRE
Mozilla Firefox before 17.0, Thunderbird before 17.0, and SeaMonkey before 2.14 assign the system principal, rather than the sandbox principal, to XMLHttpRequest objects created in sandboxes, which allows remote attackers to conduct cross-site request forgery (CSRF) attacks or obtain sensitive information by leveraging a sandboxed add-on.
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Analysis
by VulDB Data Team • 04/19/2021
The vulnerability described in CVE-2012-4205 represents a critical security flaw in the privilege separation mechanisms of Mozilla Firefox, Thunderbird, and SeaMonkey browsers. This issue stems from the improper assignment of security principals to XMLHttpRequest objects within sandboxed environments, creating a significant bypass of the browser's security model that could be exploited by remote attackers to execute cross-site request forgery attacks or extract sensitive information.
The technical flaw occurs when XMLHttpRequest objects are created within sandboxed contexts, where the system principal should be replaced with the sandbox principal to maintain proper security boundaries. However, the affected versions of these browsers incorrectly assign the system principal instead of the sandbox principal, effectively granting sandboxed add-ons the same privileges as the system itself. This misassignment creates a privilege escalation scenario where malicious code running in a sandboxed environment can make requests with elevated privileges, bypassing the intended security restrictions that separate trusted and untrusted code execution.
The operational impact of this vulnerability is severe as it enables attackers to exploit sandboxed add-ons to perform CSRF attacks against users. When a sandboxed add-on creates an XMLHttpRequest with the system principal, it can make requests to web services that would normally be restricted to the user's authenticated session. This allows attackers to manipulate web applications on behalf of users without their knowledge, potentially leading to unauthorized transactions, data exfiltration, or account takeovers. The vulnerability specifically affects the browser's security model implementation, where the sandboxing mechanism fails to properly isolate the privileges of XMLHttpRequest objects, creating a direct pathway for privilege escalation.
This vulnerability aligns with CWE-276, which describes improper privilege management, and relates to ATT&CK technique T1059.007 for command and scripting interpreter, as the flaw enables attackers to execute malicious code with elevated privileges. The issue also connects to ATT&CK technique T1566 for spearphishing with a malicious attachment, as attackers could craft malicious add-ons or extensions that exploit this vulnerability to gain unauthorized access to user sessions. Additionally, the flaw demonstrates characteristics of privilege escalation through sandbox bypass, similar to techniques described in ATT&CK technique T1548.002 for abuse of interface.
The recommended mitigation involves upgrading to the patched versions of Firefox 17.0, Thunderbird 17.0, and SeaMonkey 2.14, which properly implement the assignment of sandbox principals to XMLHttpRequest objects. Organizations should also implement security measures such as disabling or carefully vetting add-ons, particularly those from untrusted sources, and monitoring for suspicious network activity that might indicate exploitation attempts. Browser security configurations should be reviewed to ensure that sandboxing mechanisms remain effective, and users should be educated about the risks of installing unsigned or unverified extensions that could exploit this vulnerability to gain unauthorized access to their browsing sessions and associated data.