CVE-2012-5841 in Firefox
Summary
by MITRE
Mozilla Firefox before 17.0, Firefox ESR 10.x before 10.0.11, Thunderbird before 17.0, Thunderbird ESR 10.x before 10.0.11, and SeaMonkey before 2.14 implement cross-origin wrappers with a filtering behavior that does not properly restrict write actions, which allows remote attackers to conduct cross-site scripting (XSS) attacks via a crafted web site.
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Analysis
by VulDB Data Team • 04/19/2021
The vulnerability identified as CVE-2012-5841 represents a critical security flaw in Mozilla Firefox and related applications that affects versions prior to 17.0 for Firefox and Thunderbird, and 10.0.11 for Firefox ESR and Thunderbird ESR, along with SeaMonkey versions before 2.14. This issue stems from the improper implementation of cross-origin wrappers within the browser's security model, specifically failing to adequately filter write operations that should be restricted between different origins. The flaw exists in the browser's mechanism for handling cross-origin resource access, where the filtering logic does not sufficiently prevent malicious write actions that could compromise the security boundaries between different domains.
The technical implementation of this vulnerability occurs within the browser's security architecture where cross-origin wrappers are designed to mediate access between different security domains while maintaining proper isolation. However, the filtering behavior fails to properly restrict write operations, allowing malicious actors to exploit this weakness through carefully crafted web pages. This particular implementation flaw is classified under CWE-284, which deals with improper access control, specifically in the context of insufficient privilege checks during cross-origin operations. The vulnerability enables attackers to bypass the same-origin policy enforcement mechanisms that are fundamental to web security, creating a pathway for malicious code execution.
The operational impact of this vulnerability is severe as it allows remote attackers to execute cross-site scripting attacks without requiring any special privileges or user interaction beyond visiting a malicious website. Attackers can leverage this weakness to inject malicious scripts into web pages that are then executed in the context of the victim's browser session, potentially leading to session hijacking, data theft, or complete browser compromise. The attack vector operates through the manipulation of cross-origin wrapper behavior, where write operations that should be blocked are permitted, enabling attackers to modify objects or properties in ways that violate the security model. This vulnerability directly maps to ATT&CK technique T1059.007, which covers JavaScript and VBScript execution, and T1566, which involves phishing attacks that leverage web-based exploits.
Mitigation strategies for this vulnerability require immediate application of security patches to update to versions that properly implement cross-origin wrapper filtering. Organizations should ensure that all affected browsers are updated to versions 17.0 or later for Firefox and Thunderbird, and 2.14 or later for SeaMonkey, along with their respective ESR versions. Additionally, network administrators should implement content security policies and web application firewalls to add defense-in-depth measures that can detect and block suspicious cross-origin write operations. The fix addresses the underlying issue by strengthening the filtering logic within cross-origin wrappers to properly enforce write restrictions, ensuring that only authorized operations are permitted between different security domains. Security teams should also monitor for any exploitation attempts and implement proper logging to detect potential abuse of this vulnerability in their environments.