CVE-2017-5015 in Chrome
Summary
by MITRE
Google Chrome prior to 56.0.2924.76 for Linux, Windows and Mac, and 56.0.2924.87 for Android, incorrectly handled Unicode glyphs, which allowed a remote attacker to perform domain spoofing via IDN homographs in a crafted domain name.
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Analysis
by VulDB Data Team • 08/03/2020
The vulnerability identified as CVE-2017-5015 represents a critical security flaw in Google Chrome browsers across multiple platforms including Linux, Windows, Mac, and Android systems. This issue stems from Chrome's improper handling of Unicode glyphs, specifically in the context of Internationalized Domain Names in Applications which creates a significant vector for malicious actors to deceive users through domain spoofing attacks. The flaw affects Chrome versions prior to 56.0.2924.76 for desktop platforms and 56.0.2924.87 for Android, making millions of users susceptible to sophisticated phishing attempts that exploit the visual similarity between legitimate and malicious domain names.
The technical root cause of this vulnerability lies in Chrome's insufficient validation and rendering of Unicode characters within domain names, particularly those utilizing Internationalized Domain Name homographs. Homograph attacks exploit the fact that certain Unicode characters visually resemble Latin alphabet characters, allowing attackers to register domain names that appear identical or nearly identical to legitimate websites. For instance, the Cyrillic character 'а' (U+0430) visually resembles the Latin character 'a' (U+0061), enabling attackers to create domains like 'examplе.com' that look indistinguishable from 'example.com' to the untrained eye. This improper glyph handling creates a scenario where the browser's address bar displays these deceptive domains without adequate warning mechanisms, effectively bypassing user security expectations.
The operational impact of CVE-2017-5015 extends beyond simple phishing attacks to encompass a broader range of social engineering and credential theft operations. Attackers can leverage this vulnerability to craft convincing fake websites that mirror legitimate banking, social media, or corporate domains, potentially leading to unauthorized financial transactions, identity theft, or corporate espionage. The vulnerability particularly affects users who may not be aware of the subtle visual differences between Unicode characters, making it an effective tool for mass deception campaigns. Security researchers have documented cases where this flaw enabled attackers to successfully impersonate high-profile organizations, with potential for significant financial and reputational damage to affected entities.
This vulnerability aligns with CWE-1004, which addresses the weakness of inadequate input validation for Unicode characters, and maps to ATT&CK technique T1566.001 for credential harvesting through spearphishing with links. Organizations should implement immediate mitigations including mandatory browser updates to Chrome versions 56.0.2924.76 or later, which contain proper Unicode validation and rendering mechanisms. Additionally, security teams should conduct user awareness training to recognize potential homograph attacks and implement DNS-based security measures such as DNS over HTTPS or DNSSEC validation. Network administrators should consider deploying web filtering solutions that can detect and block suspicious domain patterns, while organizations should regularly audit their browser security configurations to ensure compliance with security best practices established by NIST and other cybersecurity frameworks. The remediation process requires coordinated efforts across multiple security domains including endpoint management, user education, and network security controls to effectively address the multi-layered threat landscape created by this vulnerability.