CVE-2016-2833 in Firefox
Summary
by MITRE
Mozilla Firefox before 47.0 ignores Content Security Policy (CSP) directives for cross-domain Java applets, which makes it easier for remote attackers to conduct cross-site scripting (XSS) attacks via a crafted applet.
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Analysis
by VulDB Data Team • 08/23/2022
The vulnerability described in CVE-2016-2833 represents a critical security flaw in Mozilla Firefox versions prior to 47.0 that fundamentally undermines the browser's content security policy enforcement mechanism. This weakness specifically targets the handling of cross-domain Java applets, creating a significant bypass in the browser's security model that allows malicious actors to circumvent intended protection measures. The issue stems from Firefox's failure to properly enforce Content Security Policy directives when processing Java applets that originate from different domains, effectively undermining the security boundaries that should prevent unauthorized code execution.
The technical flaw manifests in how Firefox handles the interaction between Content Security Policy and Java applet security contexts. When a web page attempts to load a Java applet from a different domain, the browser should enforce strict CSP policies that prevent such cross-domain interactions from executing malicious code. However, this vulnerability allows the browser to ignore these critical policy directives, enabling remote attackers to inject malicious applets that can execute arbitrary code within the context of the user's browser session. The flaw operates at the intersection of web security standards and Java applet security, where the browser's CSP implementation fails to properly validate cross-domain applet loading requests. This represents a direct violation of the principle of least privilege and demonstrates a failure in the browser's security architecture to properly isolate different security contexts.
The operational impact of this vulnerability is severe and far-reaching, as it significantly increases the attack surface for remote code execution and cross-site scripting attacks. Attackers can exploit this weakness by crafting malicious Java applets that appear to come from trusted sources while actually executing unauthorized code in the user's browser environment. The vulnerability enables attackers to bypass multiple layers of security protection that should normally prevent such cross-domain attacks, making it particularly dangerous in enterprise environments where users may access multiple domains and applications. This flaw directly impacts the browser's ability to protect users from malicious web content and can lead to complete compromise of user sessions, data theft, and further lateral movement within network environments. The vulnerability affects not only individual users but also organizations that rely on Firefox for web browsing and application access.
The security implications extend beyond simple XSS attacks to encompass broader threats including privilege escalation and data exfiltration. This vulnerability aligns with several ATT&CK techniques including T1059 for command and scripting interpreter and T1566 for credential access through social engineering. From a CWE perspective, this vulnerability maps to CWE-16 as a weakness in the design of security features, specifically in the implementation of content security policies. Organizations should implement immediate mitigations including updating to Firefox version 47.0 or later, which contains the necessary patches to properly enforce CSP directives for cross-domain Java applets. Additionally, security teams should consider implementing additional monitoring for suspicious applet loading activities and review existing CSP policies to ensure they adequately address cross-domain resource loading scenarios. The vulnerability also highlights the importance of comprehensive security testing for browser components and the need for proper isolation mechanisms between different security contexts within web browsers.