CVE-2018-20070 in Chrome
Summary
by MITRE
Incorrect handling of confusable characters in URL Formatter in Google Chrome prior to 71.0.3578.80 allowed a remote attacker to spoof the contents of the Omnibox (URL bar) via a crafted domain name.
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Analysis
by VulDB Data Team • 04/27/2020
The vulnerability identified as CVE-2018-20070 represents a critical security flaw in Google Chrome's URL formatting and display mechanisms that enabled sophisticated phishing attacks through Unicode character manipulation. This issue specifically affected Chrome versions prior to 71.0.3578.80 and exploited the browser's insufficient validation of confusable characters that can visually appear identical or similar to standard ASCII characters. The flaw resides in how Chrome's Omnibox component processes and displays domain names, creating a scenario where malicious actors could craft domain names using Unicode characters that closely resemble legitimate websites, thereby deceiving users into believing they are visiting trusted entities.
The technical implementation of this vulnerability stems from Chrome's inadequate handling of Unicode confusables, which are characters that look visually similar to ASCII characters but have different code points. Attackers could utilize characters from various Unicode blocks such as the cyrillic alphabet, arabic numerals, or other scripts that visually mimic latin characters. When a user visited a maliciously crafted URL, the browser would display the domain name in the Omnibox using these confusable characters, making it appear as though they were accessing a legitimate website. This behavior violates fundamental security principles of user interface design and trust establishment in web browsers, as users cannot reliably distinguish between authentic and spoofed domain names.
The operational impact of this vulnerability extends far beyond simple visual deception, as it creates a significant attack surface for phishing campaigns and credential theft operations. Security researchers have documented how attackers could leverage this flaw to impersonate well-known financial institutions, social media platforms, or government websites, leading to increased successful phishing attempts and compromised user credentials. The vulnerability directly maps to CWE-1004, which describes insufficient focus on security in the design phase, and aligns with ATT&CK technique T1566.001 for Phishing through Spearphishing Attachments, as it enables attackers to create more convincing phishing URLs. The attack vector requires no special privileges or complex exploitation techniques, making it particularly dangerous as it can be executed through standard web browsing activities.
Organizations and security professionals should implement comprehensive mitigation strategies that include immediate browser updates to Chrome version 71.0.3578.80 or later, which contains the necessary patches to address the confusable character handling. Additionally, network administrators should consider implementing URL filtering solutions and browser security extensions that can detect and block suspicious Unicode character sequences. User education remains crucial, as security awareness training should emphasize the importance of carefully examining URL addresses, particularly when conducting sensitive transactions, and verifying domain names through multiple methods beyond visual inspection alone. The vulnerability also highlights the need for continuous monitoring and updating of security policies to address emerging threats related to Unicode character manipulation in web browsers.