CVE-2015-7186 in Firefox
Summary
by MITRE
Mozilla Firefox before 42.0 on Android allows user-assisted remote attackers to bypass the Same Origin Policy and trigger (1) a download or (2) cached profile-data reading via a file: URL in a saved HTML document.
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Analysis
by VulDB Data Team • 06/26/2022
The vulnerability identified as CVE-2015-7186 represents a critical security flaw in Mozilla Firefox versions prior to 42.0 on Android platforms that undermines fundamental web security mechanisms. This vulnerability specifically targets the Same Origin Policy implementation, which serves as a cornerstone of web browser security by preventing unauthorized access to resources across different origins. The flaw allows remote attackers to execute malicious actions through user-assisted exploitation techniques that leverage file: URLs within saved HTML documents, creating a dangerous pathway for bypassing core security controls that protect users from cross-origin data access.
The technical implementation of this vulnerability stems from insufficient validation of file: URLs when processing saved HTML documents within Firefox's Android implementation. When users open HTML documents that contain file: URLs, the browser fails to properly enforce the Same Origin Policy restrictions that should prevent access to local file system resources. This weakness enables attackers to craft malicious HTML documents that, when saved and opened by victims, can trigger unauthorized downloads or read cached profile data from the local system. The vulnerability operates through a sophisticated attack vector that combines HTML document manipulation with browser security policy bypass mechanisms.
The operational impact of CVE-2015-7186 extends beyond simple data exposure, as it provides attackers with the capability to perform unauthorized file system operations that could lead to complete system compromise. Attackers can leverage this vulnerability to download malicious payloads directly to the user's device, potentially installing malware or backdoors that persist across sessions. Additionally, the ability to read cached profile data opens pathways for sensitive information extraction including browsing history, saved passwords, and other user-specific data that could be exploited for further attacks. This vulnerability particularly affects Android users who may be more susceptible to social engineering attacks through malicious email attachments or compromised websites that distribute the malicious HTML documents.
The security implications of this vulnerability align with CWE-284, which addresses improper access control mechanisms in software applications. This classification reflects the fundamental breakdown in access control enforcement that allows unauthorized operations to occur within the browser environment. From an attack framework perspective, this vulnerability maps to several ATT&CK techniques including T1193 for Spearphishing Attachment and T1059 for Command and Scripting Interpreter, as attackers can leverage this flaw to execute malicious code through crafted HTML documents. The vulnerability also demonstrates characteristics of T1071.004 for Application Layer Protocol and T1105 for Remote File Copy, as it enables attackers to transfer files to victim systems and execute commands through browser-based interfaces.
Mitigation strategies for CVE-2015-7186 primarily focus on immediate browser updates to version 42.0 or later, which contain the necessary security patches to properly enforce Same Origin Policy restrictions for file: URLs. Users should also implement strict security measures including disabling the automatic opening of HTML documents from untrusted sources, implementing content filtering systems, and maintaining regular security updates for all browser components. Network administrators should consider deploying web application firewalls that can detect and block malicious HTML content containing suspicious file: URL patterns, while security teams should monitor for indicators of compromise related to this vulnerability in their environments. The most effective long-term solution involves ensuring all users maintain up-to-date browser versions and implement comprehensive security awareness training to prevent social engineering attacks that could exploit this vulnerability.