CVE-2018-5115 in Firefox
Summary
by MITRE
If an HTTP authentication prompt is triggered by a background network request from a page or extension, it is displayed over the currently loaded foreground page. Although the prompt contains the real domain making the request, this can result in user confusion about the originating site of the authentication request and may cause users to mistakenly send private credential information to a third party site. This vulnerability affects Firefox < 58.
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Analysis
by VulDB Data Team • 07/20/2024
This vulnerability in Firefox versions prior to 58 represents a significant user interface security flaw that exploits the browser's handling of HTTP authentication prompts during background network operations. The issue arises when a webpage or browser extension initiates a background network request that triggers an HTTP authentication challenge, causing the authentication dialog to overlay the currently active foreground page. While the prompt does display the actual domain making the request, the contextual positioning creates a misleading user experience that can lead to credential compromise.
The technical flaw stems from Firefox's implementation of authentication prompt display logic, which fails to properly distinguish between foreground and background contexts when presenting authentication challenges. This creates a scenario where users may be deceived into believing they are authenticating with the currently visible website, when in reality they are responding to a request from a different domain. The vulnerability specifically affects the user interface presentation layer rather than the underlying authentication mechanisms themselves, making it particularly dangerous due to its reliance on social engineering aspects of user behavior.
The operational impact of this vulnerability extends beyond simple user confusion to represent a potential vector for credential theft and phishing attacks. When users encounter authentication prompts in unexpected locations, they may not carefully verify the requesting domain, especially if the prompt appears to be part of the currently visible page. This creates an attack surface where malicious actors could craft background requests that appear to originate from trusted domains, potentially leading to unauthorized access to sensitive accounts. The vulnerability is particularly concerning in environments where users frequently interact with multiple domains simultaneously, as the context switching increases the likelihood of user error.
Security professionals should consider this vulnerability in the context of CWE-613, which addresses insufficient session management and improper handling of authentication prompts, and its relationship to ATT&CK technique T1566, which covers credential access through social engineering. The flaw demonstrates how user interface design decisions can create security vulnerabilities that exploit human psychology rather than technical weaknesses. Organizations should ensure that Firefox installations are updated to version 58 or later, where this issue has been resolved through improved prompt display logic that properly contextualizes authentication requests. Additionally, browser security teams should implement more robust mechanisms for distinguishing between foreground and background authentication contexts to prevent similar issues in future implementations.