CVE-2008-5507 in Firefox
Summary
by MITRE
Mozilla Firefox 3.x before 3.0.5 and 2.x before 2.0.0.19, Thunderbird 2.x before 2.0.0.19, and SeaMonkey 1.x before 1.1.14 allow remote attackers to bypass the same origin policy and access portions of data from another domain via a JavaScript URL that redirects to the target resource, which generates an error if the target data does not have JavaScript syntax, which can be accessed using the window.onerror DOM API.
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Analysis
by VulDB Data Team • 08/03/2021
This vulnerability represents a critical web browser security flaw that affects multiple Mozilla products including Firefox, Thunderbird, and SeaMonkey. The issue stems from improper handling of JavaScript URLs within the browser's security model, specifically in how the same origin policy is enforced when processing redirect chains. The vulnerability allows remote attackers to circumvent fundamental web security mechanisms that prevent cross-domain data access. When a malicious JavaScript URL redirects to a target resource, the browser's error handling mechanism can be exploited to extract data from different domains, bypassing the security restrictions that normally prevent such access. The vulnerability is particularly concerning because it leverages the window.onerror DOM API, which is designed to capture JavaScript errors, to retrieve data that would otherwise be inaccessible due to cross-origin restrictions.
The technical implementation of this flaw involves a sophisticated manipulation of browser navigation and error handling systems. When a JavaScript URL is processed, if it redirects to a resource that contains valid JavaScript syntax, the browser's error handling system can be triggered in a way that exposes previously inaccessible data. The vulnerability specifically requires that the target data not have JavaScript syntax, as this would cause an error that prevents access through the window.onerror mechanism. This creates a unique exploitation vector where attackers can craft malicious JavaScript URLs that redirect through a series of pages to ultimately access cross-domain resources. The same origin policy, which is fundamental to web security and prevents scripts from accessing resources from different domains, is effectively bypassed through this technique. This vulnerability directly relates to CWE-284, which addresses improper access control, and represents a classic case of privilege escalation through improper security boundary enforcement in web browsers.
The operational impact of this vulnerability is severe and affects a wide range of users who rely on these Mozilla applications for email and web browsing. Attackers can exploit this vulnerability to perform cross-site data theft, potentially accessing sensitive information from other domains including user credentials, personal data, or corporate information. The attack vector is particularly dangerous because it can be delivered through various means including malicious email attachments, compromised websites, or social engineering campaigns that trick users into clicking on crafted links. Users of affected versions of Firefox, Thunderbird, and SeaMonkey are at significant risk, especially in enterprise environments where these applications are commonly used for both web browsing and email access. The vulnerability can be exploited even when users are browsing legitimate websites, making it particularly insidious as it can be triggered through seemingly benign navigation or page loading sequences. The attack can be automated and does not require user interaction beyond visiting a malicious page, making it a serious threat to web security.
Mitigation strategies for this vulnerability require immediate patching of affected software versions, as no reliable workarounds exist for this specific flaw. Organizations should prioritize updating all affected Mozilla applications to their patched versions, which include Firefox 3.0.5 and later, Firefox 2.0.0.19 and later, Thunderbird 2.0.0.19 and later, and SeaMonkey 1.1.14 and later. Browser security should be reinforced through regular updates and patch management procedures, as this vulnerability represents a known security flaw that was addressed through official software updates. Network administrators should also consider implementing additional security measures such as web application firewalls and content filtering solutions to detect and block malicious JavaScript URLs. The vulnerability also highlights the importance of browser security research and responsible disclosure practices, as it demonstrates how seemingly minor flaws in browser security systems can have significant implications for user data protection. Security teams should monitor for similar vulnerabilities in other browser implementations and ensure that their security monitoring systems are capable of detecting attempts to exploit such cross-origin access flaws. This vulnerability serves as a reminder of the critical importance of maintaining up-to-date browser software and the potential consequences of running outdated versions with known security flaws.