CVE-2018-6078 in Chrome
Summary
by MITRE
Incorrect handling of confusable characters in Omnibox in Google Chrome prior to 65.0.3325.146 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 • 07/20/2024
The vulnerability identified as CVE-2018-6078 represents a critical security flaw in Google Chrome's handling of confusable characters within the Omnibox interface. This issue arises from the browser's insufficient validation mechanisms when processing domain names that contain visually similar characters from different Unicode scripts. The vulnerability specifically affects Chrome versions prior to 65.0.3325.146, where the browser fails to properly distinguish between characters that appear identical or nearly identical but belong to different character sets, creating opportunities for sophisticated phishing attacks.
The technical root cause of this vulnerability lies in the browser's insufficient Unicode normalization and character validation processes within the address bar rendering system. Attackers can exploit this weakness by crafting domain names that contain confusable characters such as Cyrillic letters that visually resemble Latin characters, or other Unicode characters that are indistinguishable to the naked eye. For example, a domain name might use a Cyrillic letter "а" (U+0430) instead of the Latin letter "a" (U+0061) in a way that makes the URL appear legitimate to users who are not familiar with the character differences. This flaw operates at the intersection of CWE-176, which addresses issues with handling of confusable characters, and CWE-345, which covers insufficient verification of data integrity.
The operational impact of CVE-2018-6078 extends beyond simple phishing attacks to encompass sophisticated social engineering campaigns that can deceive even technically savvy users. When a malicious actor successfully crafts a confusable domain name, they can manipulate the Omnibox display to show a misleading URL that appears to be a legitimate website, such as a financial institution or social media platform. This creates a high-risk environment for users who may unknowingly enter sensitive information or perform transactions on compromised sites. The vulnerability essentially undermines the fundamental security principle of user trust in URL display, as the browser's visual representation no longer accurately reflects the actual domain being accessed.
The attack vector for this vulnerability is particularly insidious because it requires minimal technical expertise from the attacker while potentially causing significant damage to user security. The flaw operates without requiring any special privileges or complex exploitation techniques, making it accessible to threat actors with basic knowledge of Unicode character sets. Users may be deceived by the visual similarity of domain names, especially when they are browsing on mobile devices where screen resolution and font rendering may further obscure the differences between confusable characters. This vulnerability aligns with ATT&CK technique T1566, which covers social engineering tactics, and specifically targets the user trust model that browsers establish through their address bar interface.
Mitigation strategies for CVE-2018-6078 primarily involve updating to Chrome version 65.0.3325.146 or later, which implements proper Unicode normalization and character validation in the Omnibox handling process. Organizations should also consider implementing additional security measures such as URL filtering solutions, enhanced user education regarding phishing awareness, and regular security audits of web browsing practices. Browser vendors should continue to improve their Unicode handling mechanisms and implement more robust validation of domain names before display, particularly in contexts where user trust is paramount. The fix typically involves implementing proper Unicode normalization algorithms and character set validation that can detect and reject potentially confusable character sequences before they are rendered in the user interface, thereby preventing the spoofing of legitimate domain names through visual deception techniques.