CVE-2015-4498 in Firefox
Summary
by MITRE
The add-on installation feature in Mozilla Firefox before 40.0.3 and Firefox ESR 38.x before 38.2.1 allows remote attackers to bypass an intended user-confirmation requirement by constructing a crafted data: URL and triggering navigation to an arbitrary http: or https: URL at a certain early point in the installation process.
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Analysis
by VulDB Data Team • 10/22/2024
The vulnerability identified as CVE-2015-4498 represents a critical security flaw in Mozilla Firefox's add-on installation mechanism that fundamentally undermines user consent requirements. This issue affects Firefox versions prior to 40.0.3 and Firefox ESR 38.x versions before 38.2.1, creating a dangerous bypass condition that allows remote attackers to manipulate the installation process without proper user authorization. The flaw specifically targets the timing and validation sequence of add-on installations, exploiting a window of opportunity during the early stages of the installation process where user confirmation should be mandatory but can be circumvented through sophisticated URL manipulation techniques.
The technical implementation of this vulnerability leverages the data: URL scheme to construct malicious payloads that can trigger navigation to arbitrary http: or https: URLs at critical junctures within the installation workflow. This manipulation occurs at an early point in the installation sequence, where the browser's security checks have not yet fully initialized or validated the installation context. Attackers can craft specially formatted data: URLs that, when navigated to, effectively bypass the intended user confirmation dialogs and proceed with installation of malicious add-ons or extensions. The vulnerability stems from insufficient validation of URL navigation sequences during the add-on installation lifecycle, particularly in how the browser handles transitions between different protocol contexts during the installation process.
The operational impact of this vulnerability is severe as it enables attackers to perform unauthorized add-on installations without user knowledge or consent, potentially leading to persistent malware deployment, data exfiltration, or further compromise of the affected system. This vulnerability can be exploited through various attack vectors including phishing campaigns, malicious websites, or compromised web pages that redirect users to crafted data: URLs. The bypass of user confirmation requirements creates a significant risk for enterprise environments where browser security is paramount, as it allows attackers to silently install malicious extensions that can monitor user activity, steal credentials, or modify browser behavior. The vulnerability affects both regular Firefox releases and the extended support release versions, indicating a widespread impact across different user bases and deployment scenarios.
Security mitigations for CVE-2015-4498 primarily focus on updating to the patched versions of Firefox, specifically Firefox 40.0.3 and Firefox ESR 38.2.1, which contain the necessary fixes to properly validate URL navigation sequences during add-on installation. Organizations should implement comprehensive browser update policies to ensure all systems are running patched versions. Additionally, network administrators can deploy web filtering solutions to block access to known malicious domains and implement browser security policies that restrict add-on installations from untrusted sources. The vulnerability aligns with CWE-284 Access Control Issues, specifically concerning improper access control during critical system operations, and maps to ATT&CK technique T1176 Browser Extensions, highlighting the importance of controlling browser add-on installations as part of broader defensive strategies. Regular security assessments should include verification of browser versions and configuration settings to prevent exploitation of this and similar timing-based bypass vulnerabilities.