CVE-2023-4764: Google Chrome URL Spoofing Vulnerability

CVE-2023-4764 Overview

CVE-2023-4764 is a security user interface vulnerability affecting the BFCache (Back/Forward Cache) component in Google Chrome versions prior to 116.0.5845.179. This flaw allows remote attackers to spoof the contents of the Omnibox (URL bar) through specially crafted HTML pages, potentially deceiving users about the legitimacy of websites they visit.

Critical Impact

Remote attackers can manipulate the browser's address bar to display misleading URLs, enabling sophisticated phishing attacks and social engineering campaigns that can lead to credential theft and malware distribution.

Affected Products

• Google Chrome versions prior to 116.0.5845.179
• Debian Linux 11.0
• Debian Linux 12.0

Discovery Timeline

• 2023-09-05 - CVE-2023-4764 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-4764

Vulnerability Analysis

This vulnerability exists within Chrome's BFCache implementation, which is designed to improve page load performance by caching complete page states when users navigate away using back/forward buttons. The security flaw arises from incorrect handling of the security UI elements during cache restoration operations.

When a user navigates back to a cached page, the browser should properly restore and validate the security indicators displayed in the Omnibox. However, due to this vulnerability, an attacker can craft a malicious HTML page that exploits timing or state management issues in the BFCache restoration process. This allows the attacker to display arbitrary or spoofed content in the URL bar, making malicious sites appear to be legitimate, trusted domains.

The integrity impact is significant because users rely heavily on the URL bar as a trust indicator. When this trust anchor is compromised, users cannot reliably verify which website they are actually interacting with, opening the door to credential harvesting, drive-by downloads, and other malicious activities.

Root Cause

The root cause of CVE-2023-4764 stems from improper state management in the BFCache component's security UI update mechanism. When pages are restored from the back/forward cache, the security indicators in the Omnibox are not properly synchronized with the actual page origin and security context. This desynchronization creates a window where attackers can influence what users see in the address bar without it reflecting the true page state.

Attack Vector

The attack requires user interaction - specifically, a victim must visit an attacker-controlled webpage and then navigate using browser back/forward functionality. The attacker crafts a malicious HTML page that manipulates the BFCache behavior to display spoofed URL information when the page is restored from cache.

Attack scenario:

1. Victim visits an attacker-controlled malicious webpage
2. The page is cached by BFCache during normal navigation
3. When the victim navigates back to the cached page, the Omnibox displays spoofed content
4. The victim believes they are on a legitimate website (e.g., a banking site)
5. Credentials or sensitive information entered by the victim are captured by the attacker

The vulnerability does not require authentication and can be exploited entirely over the network through standard web browsing.

Detection Methods for CVE-2023-4764

Indicators of Compromise

• Unusual URL bar behavior observed after using browser back/forward navigation
• Reports from users about URL discrepancies between displayed address and actual page content
• Detection of crafted HTML pages attempting to manipulate BFCache behavior in web traffic logs
• Browser crash reports or anomalies related to navigation state management

Detection Strategies

• Monitor for suspicious web pages with JavaScript attempting to manipulate browser navigation history
• Implement browser version auditing across enterprise environments to identify unpatched Chrome installations
• Deploy endpoint detection solutions that can identify attempts to exploit browser UI spoofing vulnerabilities
• Review web proxy logs for patterns consistent with phishing campaigns leveraging URL spoofing techniques

Monitoring Recommendations

• Enable Chrome enterprise policies to enforce automatic updates and version compliance
• Configure security information and event management (SIEM) systems to alert on outdated browser versions
• Monitor for user reports of suspicious browser behavior, particularly related to URL bar inconsistencies
• Track phishing attempts that may be leveraging this vulnerability through threat intelligence feeds

How to Mitigate CVE-2023-4764

Immediate Actions Required

• Update Google Chrome to version 116.0.5845.179 or later immediately across all systems
• Apply Debian security updates via apt update && apt upgrade for affected Debian Linux versions
• Educate users about the risks of URL spoofing and the importance of verifying website authenticity through multiple indicators
• Consider temporarily disabling BFCache via Chrome flags (--disable-back-forward-cache) on high-security systems until patches are applied

Patch Information

Google has released a security update addressing this vulnerability in Chrome version 116.0.5845.179. The fix ensures proper synchronization of security UI elements during BFCache restoration operations. Organizations should reference the Google Chrome Update Announcement for official patch details.

For Debian Linux users, security patches are available through the Debian Security Advisory DSA-5491. Fedora and Gentoo users should also apply relevant security updates as documented in their respective security advisories.

Workarounds

• Disable BFCache functionality using Chrome command-line flags as a temporary measure
• Implement strict browser version policies using enterprise management tools to enforce minimum versions
• Deploy web application firewalls configured to detect and block potential phishing pages
• Train users to verify website identity through SSL certificate inspection rather than relying solely on URL bar content

# Disable BFCache temporarily via Chrome command line (Windows/Linux/macOS)
# Add this flag when launching Chrome as a temporary workaround
chrome --disable-back-forward-cache

# For enterprise deployments, enforce Chrome auto-updates via policy
# Linux example - create Chrome policy file
sudo mkdir -p /etc/opt/chrome/policies/managed/
echo '{"AutoUpdateCheckPeriodMinutes": 240}' | sudo tee /etc/opt/chrome/policies/managed/auto_update.json