CVE-2018-5111 in Firefox
Summary
by MITRE
When the text of a specially formatted URL is dragged to the addressbar from page content, the displayed URL can be spoofed to show a different site than the one loaded. This allows for phishing attacks where a malicious page can spoof the identify of another site. This vulnerability affects Firefox < 58.
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Analysis
by VulDB Data Team • 07/20/2024
This vulnerability represents a sophisticated user interface spoofing attack that exploits the way Firefox handles URL display during drag-and-drop operations from web content. The flaw occurs specifically when users drag text containing a specially crafted URL from webpage content into the browser's address bar, creating a deceptive visual representation that misleads users about the actual destination of their navigation. The vulnerability stems from Firefox's insufficient validation and sanitization of URL text during this particular interaction pattern, allowing attackers to manipulate the displayed URL while the underlying navigation still occurs to the malicious site. This creates a dangerous scenario where users may be convinced they are visiting a legitimate website when they are actually interacting with an attacker-controlled page.
The technical implementation of this vulnerability involves the manipulation of URL formatting and presentation logic within Firefox's browser engine. When text is dragged from web content, the browser's address bar parsing mechanism fails to properly distinguish between the actual URL being navigated to and the text being displayed for user convenience. This discrepancy allows attackers to craft URL text that appears legitimate in the address bar while simultaneously triggering navigation to a malicious domain. The vulnerability specifically affects versions prior to Firefox 58, indicating that the issue was present in the browser's core URL handling and address bar rendering components. This represents a classic case of insufficient input validation and output encoding, which aligns with CWE-1004 weakness category focusing on insecure default settings and improper handling of user-supplied data.
The operational impact of this vulnerability extends beyond simple phishing attacks to encompass a broader range of social engineering threats that can compromise user trust and security. Attackers can exploit this flaw to create convincing fake login pages, banking interfaces, or official website representations that appear legitimate to unsuspecting users. The vulnerability is particularly dangerous because it operates at the user interface level where trust is established, making it more effective than traditional phishing methods that rely on email deception or website redirection. Users who are accustomed to checking URL addresses for legitimacy may be misled by the spoofed display, potentially leading to credential theft, financial fraud, or other malicious activities. The attack vector is particularly effective because it leverages normal browser behavior and user expectations, making detection and prevention more challenging for both users and security systems.
Mitigation strategies for this vulnerability require a multi-layered approach focusing on both browser updates and user awareness training. The primary and most effective mitigation is upgrading to Firefox version 58 or later, where the underlying URL handling and address bar display logic has been corrected. Organizations should implement comprehensive patch management procedures to ensure all browsers are updated promptly, particularly given the widespread use of Firefox in enterprise environments. Security teams should also consider implementing browser security policies that restrict drag-and-drop functionality in sensitive environments or provide additional URL verification mechanisms. Additionally, user education programs should emphasize the importance of verifying website certificates and URLs even when the address bar appears to display a legitimate site. This vulnerability demonstrates the importance of considering user interface security implications and the potential for seemingly benign browser features to become attack vectors, aligning with ATT&CK technique T1531 which covers the use of malicious web content to deceive users.