CVE-2017-5090 in Chrome
Summary
by MITRE
Insufficient Policy Enforcement in Omnibox in Google Chrome prior to 59.0.3071.115 for Mac allowed a remote attacker to perform domain spoofing via a crafted domain name containing a U+0620 character, aka Apple rdar problem 32458012.
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Analysis
by VulDB Data Team • 01/20/2021
The vulnerability identified as CVE-2017-5090 represents a critical policy enforcement failure within Google Chrome's omnibox component, specifically affecting versions prior to 59.0.3071.115 on macOS platforms. This flaw stems from inadequate handling of Unicode characters during domain name validation and display processes, creating a pathway for sophisticated phishing attacks. The vulnerability manifests when a malicious actor crafts a domain name containing the U+0620 character, which is a Persian letter known as "kaf" in Arabic script, allowing for deceptive visual similarities that can fool users into believing they are visiting legitimate websites.
The technical exploitation of this vulnerability relies on the Unicode character U+0620's visual similarity to other commonly used characters in domain names, particularly when rendered in the browser's address bar. This character rendering issue creates a domain spoofing opportunity where attackers can construct malicious domains that appear visually indistinguishable from trusted websites. The flaw operates at the intersection of Unicode normalization, character encoding, and user interface rendering, where the browser's policy enforcement mechanisms fail to properly validate and sanitize domain names containing specific Unicode characters before displaying them in the omnibox.
From an operational perspective, this vulnerability poses significant risks to user security and trust within the Chrome ecosystem. Attackers can leverage this weakness to craft deceptive URLs that closely resemble legitimate domains, potentially leading to credential theft, financial fraud, or data exfiltration. The attack vector requires only a remote server hosting the malicious website, making it particularly dangerous as it can be deployed at scale without requiring physical access to the target system. Users may not recognize the deception due to the visual similarity of the spoofed domain names, creating an effective social engineering attack vector that bypasses traditional security measures.
The impact of this vulnerability extends beyond simple phishing attacks, as it undermines fundamental security assumptions about domain validation and user interface trust. This flaw aligns with CWE-174, which addresses insufficient policy enforcement in user interface components, and demonstrates how Unicode handling can create security gaps in application design. From an ATT&CK framework perspective, this vulnerability maps to techniques involving credential access through deception and user execution of malicious content, as users may be tricked into believing they are visiting legitimate sites. The vulnerability also relates to privilege escalation concepts, as it allows attackers to effectively gain access to user sessions through visual deception rather than direct exploitation of system vulnerabilities.
Mitigation strategies for CVE-2017-5090 primarily focus on immediate software updates to Chrome versions 59.0.3071.115 and later, which contain the necessary policy enforcement fixes and Unicode handling improvements. Organizations should implement comprehensive patch management procedures to ensure all Chrome installations are updated promptly, as this vulnerability affects users across all operating systems where the affected versions are deployed. Additional protective measures include user education about the importance of verifying URLs, particularly for sensitive transactions, and implementing browser security extensions that provide additional URL validation. Network-level protections such as DNS filtering and web content filtering solutions can provide additional layers of defense, though these should not be relied upon as primary mitigations. The fix implemented by Google addresses the core policy enforcement gap by improving Unicode character validation and normalization within the omnibox rendering process, ensuring that domain names containing potentially deceptive Unicode characters are properly sanitized before display to users.