CVE-2012-3965 in Firefox
Summary
by MITRE
Mozilla Firefox before 15.0 does not properly restrict navigation to the about:newtab page, which allows remote attackers to execute arbitrary JavaScript code with chrome privileges via a crafted web site that triggers creation of a new tab and then a new window.
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Analysis
by VulDB Data Team • 01/31/2018
The vulnerability identified as CVE-2012-3965 represents a critical security flaw in Mozilla Firefox versions prior to 15.0 that stems from inadequate restrictions on navigation to the about:newtab page. This issue fundamentally undermines the browser's security model by allowing malicious web content to exploit the tab creation mechanism and subsequently execute code with chrome privileges. The flaw exists within the browser's handling of new tab and window creation processes, creating an attack vector that bypasses standard security boundaries.
The technical implementation of this vulnerability involves a sophisticated manipulation of Firefox's tab management system where remote attackers can craft malicious websites that trigger the creation of new tabs and subsequently new windows. When these new windows are created, they inherit chrome privileges from the browser's privileged context, enabling attackers to execute arbitrary JavaScript code with elevated permissions. This represents a privilege escalation vulnerability that operates through the browser's legitimate tab creation APIs but exploits them in unintended ways.
The operational impact of CVE-2012-3965 is severe as it allows attackers to bypass the same-origin policy and other security mechanisms that normally protect the browser's privileged chrome environment. Once executed, the malicious JavaScript code can perform actions such as reading and modifying browser configuration files, accessing sensitive user data, modifying browser extensions, and potentially exfiltrating information. The vulnerability specifically targets the browser's security model by exploiting the implicit trust relationship between the browser's chrome UI and newly created windows.
This vulnerability aligns with CWE-264, which addresses permissions, privileges, and access control issues, and maps to ATT&CK technique T1059.007 for JavaScript execution within the browser environment. The attack chain typically involves initial compromise through a malicious website, followed by tab manipulation that creates a new window with elevated privileges, and finally code execution with chrome-level access. Organizations using affected Firefox versions face significant risk as this vulnerability can be exploited through standard web browsing activities without requiring any special user interaction beyond visiting a malicious site.
The recommended mitigation strategy involves immediate upgrade to Firefox version 15.0 or later where this vulnerability has been addressed through enhanced restrictions on about:newtab navigation and improved window creation security checks. Additionally, administrators should implement browser security policies that limit tab creation and window manipulation capabilities, while security teams should monitor for indicators of compromise related to this specific attack vector. Network-level protections such as content filtering and web application firewalls can provide additional defense-in-depth measures, though the primary solution remains the software update to address the underlying implementation flaw.