CVE-2017-5076 in Chrome
Summary
by MITRE
Insufficient Policy Enforcement in Omnibox in Google Chrome prior to 59.0.3071.86 for Mac, Windows, and Linux, and 59.0.3071.92 for Android, 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 • 01/04/2023
The vulnerability described in CVE-2017-5076 represents a critical weakness in Google Chrome's handling of internationalized domain names within the omnibox component, which serves as the browser's address bar interface. This flaw stems from insufficient policy enforcement mechanisms that fail to properly validate and display domain names containing internationalized domain name homographs. The vulnerability affects multiple platforms including macOS, Windows, Linux, and Android versions prior to the specified patched releases, creating a widespread security risk across various user environments. The core issue lies in how Chrome processes and displays domain names that utilize characters from different alphabets or scripts that may visually appear identical or similar to ASCII characters, creating opportunities for malicious actors to exploit user trust in the browser interface.
The technical implementation of this vulnerability exploits the fundamental principle of domain name security through internationalized domain name (IDN) homograph attacks, where attackers register domain names using characters from non-Latin scripts that visually resemble common ASCII characters. When users encounter such domain names in the omnibox, the browser fails to properly distinguish between legitimate and malicious variants, allowing attackers to create deceptive URLs that appear authentic to unsuspecting users. This flaw operates at the intersection of Unicode character handling, browser rendering engines, and user interface security policies, where the visual representation of domain names does not accurately reflect the underlying DNS resolution process. The vulnerability specifically impacts the omnibox's URL display logic and does not require user interaction beyond visiting the malicious site, making it particularly dangerous for phishing attacks that rely on visual deception.
The operational impact of this vulnerability extends beyond simple phishing attempts to encompass broader security implications for user trust and browser security assumptions. Attackers can exploit this weakness to create convincing fake websites that appear legitimate to users who may not notice the subtle visual differences between internationalized and standard ASCII characters. This creates a significant risk for credential theft, data exfiltration, and other malicious activities that rely on user deception. The vulnerability affects all users regardless of their technical sophistication, as the visual deception occurs at the browser interface level where users expect to see clear and accurate representation of website addresses. Security researchers have noted that this type of attack can bypass traditional security measures such as SSL certificate validation because the deception occurs at the visual presentation layer rather than the network protocol level, making it particularly challenging to detect through conventional security monitoring approaches.
Mitigation strategies for CVE-2017-5076 primarily focus on immediate software updates to the affected Chrome versions, which implement proper IDN validation and display policies. Organizations should prioritize patch management to ensure all affected systems receive the security updates, as the vulnerability represents a persistent risk for users who continue to operate on unpatched browsers. Browser vendors have since implemented more robust IDN handling policies that include visual warnings when internationalized domain names are detected, aligning with industry best practices for internationalized domain name security. The vulnerability demonstrates the importance of implementing comprehensive policy enforcement mechanisms in user-facing components, particularly those that handle potentially deceptive visual elements. This case study emphasizes the need for security controls that consider both technical implementation flaws and user interface design considerations, as the vulnerability's exploitation relies on the intersection of both areas. Organizations should also consider implementing additional security measures such as URL filtering, user education about visual deception techniques, and monitoring for suspicious domain name patterns to provide layered protection against similar vulnerabilities. The incident highlights the critical need for continuous security testing of user interface components, particularly those that directly interact with user trust and authentication processes, as these areas often represent the most common attack vectors for social engineering and phishing campaigns.