CVE-2017-15425 in Chrome
Summary
by MITRE
Insufficient policy enforcement in Omnibox in Google Chrome prior to 63.0.3239.84 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 • 05/06/2023
The vulnerability CVE-2017-15425 represents a critical security flaw in Google Chrome's Omnibox implementation that enabled remote attackers to conduct domain spoofing attacks through the use of internationalized domain names with homograph characters. This issue affected Chrome versions prior to 63.0.3239.84 and exploited the browser's insufficient policy enforcement mechanisms when processing domain names containing characters that visually resemble standard ascii characters but have different unicode code points. The flaw specifically targeted the way Chrome handled internationalized domain names where attackers could register domains using characters from different scripts or unicode ranges that appear identical or nearly identical to legitimate domain names in ascii characters.
The technical implementation of this vulnerability stems from the browser's handling of internationalized domain names and the lack of proper validation when displaying domain information in the address bar. When users encountered a crafted domain name containing homograph characters, the browser would display the domain in a way that made it appear identical to a legitimate website, allowing attackers to deceive users into believing they were visiting a trusted site. This occurs because certain unicode characters from different character sets can visually match ascii characters used in domain names, creating a scenario where users cannot distinguish between legitimate and malicious domains through visual inspection alone. The vulnerability specifically affects the display and validation logic in Chrome's address bar and URL parsing components.
The operational impact of this vulnerability extends beyond simple phishing attacks to encompass a broader range of social engineering and man-in-the-middle scenarios. Attackers could exploit this flaw to create malicious domains that visually appear identical to well-known legitimate websites, potentially leading to credential theft, financial fraud, or data exfiltration. The attack vector is particularly dangerous because it operates at the user interface level where trust is established, making it difficult for users to detect malicious activity even when they are vigilant about security. This vulnerability effectively undermines the user's ability to verify website authenticity through visual inspection of the address bar, which is a fundamental security mechanism in web browsers.
The mitigation for this vulnerability required Chrome to implement stricter policy enforcement for internationalized domain names and improve the handling of unicode characters in URL display. Google addressed this issue by enhancing the browser's domain validation logic to properly detect and handle homograph characters, ensuring that visually similar characters from different unicode ranges are appropriately flagged or displayed to users. This fix aligns with the principles outlined in CWE-1004 which addresses weaknesses in security policies and enforcement mechanisms, specifically focusing on the proper validation of input data. Organizations should ensure their Chrome installations are updated to version 63.0.3239.84 or later to prevent exploitation of this vulnerability. The remediation process involves updating the browser software and implementing user education about the importance of verifying website authenticity through certificate inspection rather than relying solely on visual appearance of URLs. This vulnerability also relates to ATT&CK technique T1566 which covers social engineering through phishing, demonstrating how browser-level flaws can be exploited to create more sophisticated attack vectors.