CVE-2023-6210 in Firefox
Summary
by MITRE • 11/21/2023
When an https: web page created a pop-up from a "javascript:" URL, that pop-up was incorrectly allowed to load blockable content such as iframes from insecure http: URLs This vulnerability affects Firefox < 120.
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Analysis
by VulDB Data Team • 12/15/2023
This vulnerability represents a critical security flaw in Firefox browser's handling of mixed content policies, specifically affecting versions prior to 120. The issue occurs when a web page served over secure https protocol creates a pop-up window using a javascript: URL scheme, which then incorrectly permits the loading of blockable content from insecure http sources. This fundamental breakdown in security policy enforcement creates an avenue for attackers to bypass intended security measures that should prevent loading of unencrypted resources in secure contexts. The vulnerability stems from Firefox's improper validation of content loading permissions within pop-up windows that originate from secure contexts, allowing malicious actors to inject insecure resources through seemingly legitimate javascript pop-ups.
The technical flaw manifests in Firefox's mixed content blocking mechanism which fails to properly enforce security boundaries when javascript: URLs generate pop-up windows. When a secure https page executes javascript: URLs that open new windows, the browser should maintain the security context and prevent loading of http resources, but instead allows such content to load. This creates a scenario where attackers can leverage legitimate pop-up functionality to circumvent security controls designed to prevent mixed content loading. The vulnerability specifically affects the browser's security policy enforcement within the context of pop-up windows, where the security context of the originating page is not properly maintained for subsequent content loading decisions. This represents a violation of the principle of least privilege and secure content handling that should be maintained across all browser security mechanisms.
The operational impact of this vulnerability is significant as it allows for the execution of insecure content within contexts that should be secure, potentially enabling man-in-the-middle attacks, credential theft, and other malicious activities. Attackers can exploit this to load malicious iframes or other content from http sources even when the originating page is secure, effectively bypassing the browser's intended security protections. This vulnerability particularly impacts users browsing secure websites who may encounter pop-ups that load insecure resources, potentially exposing them to attacks that would normally be blocked by the browser's security policies. The flaw undermines user trust in the security of https connections and can be exploited in various attack vectors including phishing, credential harvesting, and data exfiltration.
Mitigation strategies should focus on immediate browser updates to version 120 or later where this vulnerability has been addressed. Organizations should implement comprehensive browser security policies that enforce automatic updates and monitor for vulnerable browser versions in their environments. Security teams should conduct vulnerability assessments to identify systems running affected Firefox versions and ensure proper patch management procedures are in place. Additionally, web developers should be aware of this vulnerability and implement proper content security policies that do not rely on browser security mechanisms alone, while also ensuring their applications properly handle mixed content scenarios. The fix implemented by Mozilla addresses the core issue by strengthening the security context validation for pop-up windows created from javascript: URLs, ensuring that the originating secure context is properly maintained when loading subsequent content. This aligns with established security principles and represents a correction to the security model that was previously allowing inappropriate content loading in secure contexts.
This vulnerability maps to CWE-346: "Origin Validation Error and CWE-355: "Security-Related Header Not Set" within the Common Weakness Enumeration framework, demonstrating a failure in proper origin validation and content security enforcement. The attack surface aligns with ATT&CK technique T1071.004: "Application Layer Protocol: DNS" and T1566: "Phishing" as attackers can leverage this to load malicious content through seemingly legitimate pop-ups. The vulnerability represents a failure in the browser's security model enforcement and demonstrates the critical importance of maintaining consistent security policies across all browser functionalities, particularly those involving window creation and content loading mechanisms.