CVE-2015-0798 in Firefox
Summary
by MITRE
The Reader mode feature in Mozilla Firefox before 37.0.1 on Android, and Desktop Firefox pre-release, does not properly handle privileged URLs, which makes it easier for remote attackers to execute arbitrary JavaScript code with chrome privileges by leveraging the ability to bypass the Same Origin Policy.
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Analysis
by VulDB Data Team • 05/02/2022
The vulnerability identified as CVE-2015-0798 represents a critical security flaw in Mozilla Firefox's Reader mode implementation across both Android and desktop platforms. This issue stems from insufficient validation of privileged URLs within the reader mode functionality, creating a pathway for malicious actors to exploit the browser's security model. The flaw specifically affects Firefox versions prior to 37.0.1 on Android and pre-release desktop versions, leaving users exposed to sophisticated attack vectors that could compromise their browsing environment.
The technical root cause of this vulnerability lies in Firefox's improper handling of privileged URLs within its Reader mode feature. When users activate Reader mode to view web content in a simplified format, the browser should maintain strict security boundaries to prevent unauthorized access to privileged resources. However, the implementation failed to adequately validate URL origins, allowing attackers to craft malicious content that could bypass the Same Origin Policy mechanisms. This policy is fundamental to web security, preventing scripts from one origin from accessing resources from another origin without proper authorization. The failure in this validation creates a direct pathway for privilege escalation.
The operational impact of this vulnerability is severe and multifaceted. Remote attackers can exploit this flaw to execute arbitrary JavaScript code with chrome privileges, which represents a significant escalation from regular user-level scripting capabilities. Chrome privileges provide access to browser internals and system resources that normal web content should never be able to access. This means attackers could potentially read sensitive data, modify browser behavior, inject malicious content into other websites, or even gain access to user credentials stored in the browser. The ability to bypass the Same Origin Policy fundamentally undermines the security model that protects users from cross-site scripting attacks and other web-based exploits.
From a cybersecurity perspective, this vulnerability aligns with CWE-200, which covers "Information Exposure," and CWE-352, addressing "Cross-Site Request Forgery," as the flaw enables unauthorized access to privileged resources through manipulated URL handling. The attack vector also maps to ATT&CK technique T1059.007, "Command and Scripting Interpreter: JavaScript," where adversaries leverage JavaScript execution capabilities to gain elevated privileges. Additionally, this vulnerability demonstrates characteristics of privilege escalation attacks that could be classified under ATT&CK technique T1068, "Exploitation for Privilege Escalation," where attackers exploit software flaws to gain higher-level permissions.
The mitigation strategy for this vulnerability requires immediate patching of affected Firefox versions to 37.0.1 or later, which includes enhanced URL validation and stricter enforcement of the Same Origin Policy within Reader mode functionality. Organizations should implement comprehensive browser update policies and consider deploying automated patch management systems to ensure all users maintain current security protections. Security teams should also monitor for any exploitation attempts through network traffic analysis and browser security logging, as this vulnerability would likely generate unusual JavaScript execution patterns or unauthorized access attempts to privileged browser resources. Additionally, user education regarding the importance of keeping browsers updated and avoiding untrusted websites remains critical in defending against such exploitation attempts.