CVE-2018-6175 in Chrome
Summary
by MITRE
Incorrect handling of confusable characters in URL Formatter in Google Chrome prior to 68.0.3440.75 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 • 07/17/2024
The vulnerability identified as CVE-2018-6175 represents a critical security flaw in Google Chrome's URL formatting mechanism that enabled sophisticated domain spoofing attacks through the manipulation of internationalized domain names. This issue specifically affected Chrome versions prior to 68.0.3440.75 and exploited the improper handling of confusable characters that are visually similar but technically distinct, creating opportunities for malicious actors to deceive users into believing they were visiting legitimate websites while actually accessing fraudulent ones. The vulnerability falls under the category of Unicode confusability attacks, where characters from different scripts or character sets appear visually identical or nearly identical to the human eye, yet are represented by different Unicode code points that are not properly normalized during URL processing.
The technical root cause of this vulnerability lies in Chrome's insufficient validation and normalization of internationalized domain names during URL display and processing. When users encountered domain names containing confusable characters, the browser failed to properly distinguish between legitimate international characters and maliciously crafted homograph characters that could visually mimic well-known domain names. This flaw was particularly dangerous because it allowed attackers to register domain names using characters that look identical to English characters but are actually from different character sets such as Cyrillic, Arabic, or other Unicode scripts. The improper URL formatting logic did not adequately implement Unicode normalization or confusability checks that would have flagged or converted these potentially deceptive domain names into their canonical representations, enabling attackers to craft URLs that appear authentic to unsuspecting users.
The operational impact of CVE-2018-6175 was significant as it created a vector for highly effective phishing attacks and social engineering campaigns that could bypass traditional security measures and user vigilance. Attackers could register domains using visually identical characters to popular websites such as google.com, paypal.com, or bank websites, tricking users into entering sensitive information on malicious sites that appeared to be legitimate. This vulnerability specifically targeted the user trust model that relies on visual URL verification, where users often make quick judgments about website legitimacy based on the appearance of domain names in their browser's address bar. The attack could be executed without requiring any additional exploits or user interaction beyond visiting the malicious website, making it particularly dangerous for widespread deployment in credential harvesting campaigns and financial fraud operations.
Organizations and security professionals addressing this vulnerability should implement multiple layers of defense including immediate browser updates to the patched versions of Chrome, deployment of network monitoring tools to detect suspicious domain name patterns, and enhanced user education regarding the risks of visual URL deception. The mitigation strategy should include regular security audits of domain registration practices, implementation of DNS security extensions, and deployment of web application firewalls that can detect and block known malicious domain patterns. This vulnerability aligns with attack patterns documented in the attack tree methodology where domain spoofing represents a common entry point for advanced persistent threats. The issue also relates to CWE-1004 which addresses insufficient Unicode normalization in security-critical applications, and maps to ATT&CK technique T1566 which covers spearphishing through social engineering. Organizations should consider implementing additional security controls such as certificate pinning, extended validation certificates, and automated URL reputation checking systems to provide defense-in-depth against similar confusability attacks that could exploit similar weaknesses in other applications or browser implementations.