CVE-2018-6098 in Chrome
Summary
by MITRE
Incorrect handling of confusable characters in URL Formatter in Google Chrome prior to 66.0.3359.106 allowed a remote attacker to perform domain spoofing via IDN homographs via a crafted domain name.
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Analysis
by VulDB Data Team • 06/13/2023
The vulnerability identified as CVE-2018-6098 represents a critical security flaw in Google Chrome's URL formatting mechanism that exploited the handling of confusable characters in internationalized domain names. This issue specifically affected Chrome versions prior to 66.0.3359.106 and enabled remote attackers to execute domain spoofing attacks through the manipulation of internationalized domain name homographs. The vulnerability stems from the browser's inadequate processing of Unicode characters that appear visually similar but have different underlying code points, creating opportunities for malicious actors to craft deceptive domain names that masquerade as legitimate websites.
The technical implementation of this vulnerability resides in Chrome's URL formatter component which failed to properly normalize and validate internationalized domain names before displaying them to users. When users encountered crafted domain names containing confusable characters such as the latin letter 'l' (U+006C) alongside the cyrillic letter 'l' (U+0455) or the greek letter 'l' (U+03B9), the browser would display them in a manner that obscured their true identity. This flaw aligns with CWE-1004 which addresses the improper handling of confusable characters in security contexts, specifically targeting the weakness in character normalization and validation processes.
The operational impact of CVE-2018-6098 extends beyond simple visual deception to encompass significant security risks for end users and organizations. Attackers could exploit this vulnerability by registering domain names that visually resemble well-known legitimate websites such as "google.com" but contain subtle character differences that are nearly imperceptible to the human eye. This capability enabled phishing attacks where victims might be tricked into believing they were visiting trusted sites while actually navigating to malicious domains controlled by threat actors. The vulnerability particularly affected users who relied on Chrome for browsing activities and could potentially lead to credential theft, malware distribution, and financial fraud.
Mitigation strategies for this vulnerability required immediate browser updates to version 66.0.3359.106 or later, which implemented enhanced normalization of internationalized domain names and improved validation of confusable characters. Organizations should have deployed security patches promptly and considered implementing additional protective measures such as DNS-based security solutions, web application firewalls, and user education programs focused on recognizing potential phishing attempts. The fix addressed the core issue by introducing stricter character validation processes and ensuring that domain names containing potentially confusable characters are properly displayed to users in a manner that prevents visual deception. This vulnerability also highlighted the importance of following security best practices outlined in the ATT&CK framework, particularly those related to credential access and defense evasion techniques that attackers might employ through such domain spoofing methods. The incident underscored the necessity of robust internationalized domain name handling in web browsers and contributed to the broader security community's understanding of Unicode character handling in security-sensitive contexts.