CVE-2007-5947 in Firefox
Summary
by MITRE
The jar protocol handler in Mozilla Firefox before 2.0.0.10 and SeaMonkey before 1.1.7 retrieves the inner URL regardless of its MIME type, and considers HTML documents within a jar archive to have the same origin as the inner URL, which allows remote attackers to conduct cross-site scripting (XSS) attacks via a jar: URI.
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Analysis
by VulDB Data Team • 01/12/2025
The vulnerability described in CVE-2007-5947 represents a critical security flaw in the jar protocol handler implementation within Mozilla Firefox versions prior to 2.0.0.10 and SeaMonkey versions prior to 1.1.7. This issue stems from improper handling of MIME type validation when processing jar archive contents, creating a fundamental breach in web browser security mechanisms that should prevent cross-site scripting attacks. The flaw specifically targets the origin policy enforcement mechanism that normally protects against malicious code execution across different domains and contexts.
The technical implementation of this vulnerability occurs when the browser processes jar: URIs and fails to properly validate the MIME type of content contained within jar archives. Normally, web browsers enforce strict origin policies that prevent documents from different origins from interacting with each other, particularly when one document attempts to access resources or execute code from another origin. However, the jar protocol handler in affected versions indiscriminately retrieves inner URLs from jar archives without proper MIME type checking, allowing HTML documents within these archives to be treated as having the same origin as the outer URL. This bypasses the fundamental security boundary that should separate content from different sources.
This vulnerability creates a severe operational impact by enabling remote attackers to execute cross-site scripting attacks through carefully crafted jar archives. Attackers can embed malicious HTML content within jar files and deliver them to victims through various attack vectors, such as malicious websites or email attachments. The exploited behavior allows attackers to inject malicious scripts that can execute in the context of the victim's browser session, potentially leading to session hijacking, data theft, or complete system compromise. The flaw essentially allows attackers to circumvent the same-origin policy that forms the cornerstone of web security architecture.
The security implications of this vulnerability align with CWE-94, which describes "Improper Control of Generation of Code ('Code Injection')" and specifically relates to the improper handling of code generation in web browsers. From an ATT&CK framework perspective, this vulnerability maps to T1211 - "Exploitation for Defense Evasion" and T1059 - "Command and Scripting Interpreter" as attackers can leverage the XSS capability to execute malicious code within the victim's browser environment. The vulnerability represents a classic case of privilege escalation through improper input validation, where the jar protocol handler fails to properly validate the content it processes.
Mitigation strategies for this vulnerability include immediate upgrading to Firefox 2.0.0.10 or later versions and SeaMonkey 1.1.7 or later, which contain the necessary patches to properly validate MIME types and enforce correct origin policies for jar protocol handling. Organizations should also implement network-level protections such as content filtering and web application firewalls to prevent access to malicious jar archives. Additionally, security awareness training for users can help reduce the risk of encountering malicious jar files through social engineering attacks. The fix implemented by Mozilla developers involved strengthening the MIME type validation process within the jar protocol handler to ensure that HTML documents within jar archives are properly isolated from the outer URL context, thereby restoring the intended same-origin policy enforcement mechanism.