CVE-2017-15394 in Chrome
Summary
by MITRE
Insufficient Policy Enforcement in Extensions in Google Chrome prior to 62.0.3202.62 allowed a remote attacker to perform domain spoofing in permission dialogs via IDN homographs in a crafted Chrome Extension.
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Analysis
by VulDB Data Team • 02/06/2023
This vulnerability resides in the Chrome extension permission system where inadequate policy enforcement allows malicious actors to exploit internationalized domain name homographs. The flaw specifically affects Google Chrome versions prior to 62.0.3202.62 and enables attackers to craft extensions that display deceptive domain names in permission dialogs. The vulnerability stems from the browser's insufficient validation of internationalized domain names during extension installation and permission prompts, allowing cybercriminals to create extensions that appear to originate from legitimate domains through the use of visually similar unicode characters from different scripts.
The technical implementation of this vulnerability exploits the differences between standard ascii domain names and internationalized domain names that use unicode characters from various languages. Attackers can register or craft extensions with domain names that contain unicode characters that visually resemble ascii characters from the target domain. For example, a domain name might use cyrillic characters that look identical to latin characters in permission prompts, creating a false sense of security for users who may unknowingly grant permissions to malicious extensions. This represents a classic case of character encoding confusion that violates the principle of least privilege in extension security.
The operational impact of this vulnerability extends beyond simple domain spoofing to encompass full privilege escalation through user interaction. When users see permission dialogs displaying what appears to be a legitimate domain, they are more likely to grant permissions to extensions that may then access sensitive user data, cookies, or perform malicious actions. The attack vector relies on user trust in the visual appearance of domain names rather than technical validation, making it particularly dangerous in phishing scenarios. This vulnerability directly impacts the chrome extension security model and undermines user confidence in the browser's permission system, as users cannot rely on visual domain verification to distinguish between legitimate and malicious extensions.
Mitigation strategies for this vulnerability include upgrading to Chrome version 62.0.3202.62 or later where proper IDN validation has been implemented. Organizations should also implement extension whitelisting policies and regularly audit installed extensions to identify potentially malicious software. The fix implemented by google addresses the core issue by strengthening the validation of internationalized domain names in extension permission dialogs, ensuring that unicode characters are properly handled and displayed in a way that prevents visual deception. This aligns with security best practices outlined in the cwe-174 category for weak validation of internationalized domain names and represents a critical improvement in browser security architecture.
The vulnerability demonstrates how modern browsers must account for internationalization and localization issues in security contexts, particularly when dealing with user-facing interfaces that display domain information. It highlights the importance of proper unicode handling in security-critical components and the need for comprehensive testing of internationalized character sets in permission systems. From an att&ck perspective, this vulnerability maps to technique t1059.001 for execution through browser extensions and t1566.001 for social engineering via deceptive domain presentation. The remediation process requires both immediate patching and long-term security awareness training to help users recognize potential deception attempts in extension permission prompts.