CVE-2016-5288 in Firefox
Summary
by MITRE
Web content could access information in the HTTP cache if e10s is disabled. This can reveal some visited URLs and the contents of those pages. This issue affects Firefox 48 and 49. This vulnerability affects Firefox < 49.0.2.
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Analysis
by VulDB Data Team • 09/28/2022
The vulnerability identified as CVE-2016-5288 represents a significant security flaw in the Firefox web browser that emerged from the complex interaction between its multi-process architecture and HTTP cache handling mechanisms. This issue specifically targets Firefox versions 48 and 49, where the implementation of the e10s (Electrolysis) feature was still in development stages, creating a critical gap in access control that could be exploited by malicious web content. The vulnerability stems from the browser's inability to properly enforce cache isolation when the e10s feature is disabled, allowing web pages to access cached HTTP content that should remain restricted to the browser's internal processes.
The technical flaw manifests through a cache information disclosure mechanism where web content can directly query the HTTP cache to retrieve sensitive information about previously visited URLs and their corresponding page contents. This occurs because the cache access controls become bypassed when e10s is disabled, enabling malicious scripts to exploit the underlying cache infrastructure to gather information about user browsing history and cached resources. The vulnerability is particularly concerning because it operates at the application layer and can be triggered through standard web page execution without requiring any special privileges or elevated access rights from the user. This type of information disclosure vulnerability maps directly to CWE-200, which categorizes weaknesses related to information exposure, and falls under the broader category of cache-related security flaws that compromise user privacy and browsing integrity.
The operational impact of CVE-2016-5288 extends beyond simple information leakage, as it creates potential pathways for more sophisticated attacks that could lead to session hijacking, cross-site tracking, and comprehensive user behavior profiling. Attackers could leverage this vulnerability to construct detailed profiles of user activities by accessing cached versions of sensitive pages, including login forms, financial transactions, and private communications. The vulnerability affects not only individual user privacy but also organizational security posture, as it could enable adversaries to gather intelligence about internal network activities or sensitive business operations that users might access through Firefox. This type of attack vector aligns with ATT&CK technique T1566, which covers credential access through various means including cache manipulation, and represents a significant threat to user confidentiality and data protection standards.
Mitigation strategies for this vulnerability require immediate patching to Firefox version 49.0.2 or later, where the underlying cache access controls have been properly implemented and enforced. Organizations should also consider implementing additional network-level monitoring to detect potential exploitation attempts and establish policies requiring regular browser updates as part of their security maintenance procedures. Security teams should conduct thorough vulnerability assessments to ensure that all Firefox installations within their environment are properly updated and that e10s remains enabled to prevent exploitation of this specific weakness. The vulnerability serves as a reminder of the critical importance of proper isolation mechanisms in multi-process browser architectures and highlights the need for comprehensive security testing of browser features that handle sensitive user data and cache information, particularly when dealing with legacy configurations that disable newer security enhancements.