CVE-2021-21205 in Chrome
Summary
by MITRE • 04/26/2021
Insufficient policy enforcement in navigation in Google Chrome on iOS prior to 90.0.4430.72 allowed a remote attacker to bypass navigation restrictions via a crafted HTML page.
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Analysis
by VulDB Data Team • 04/30/2021
The vulnerability identified as CVE-2021-21205 represents a critical policy enforcement failure within Google Chrome's implementation on iOS platforms. This issue specifically affects versions prior to 90.0.4430.72 and stems from inadequate restrictions on navigation behavior that could be exploited by remote attackers. The flaw manifests in how Chrome handles navigation policies, particularly when processing crafted HTML content that attempts to circumvent established security boundaries. This vulnerability resides in the browser's security model where navigation restrictions intended to prevent unauthorized access or redirection are insufficiently enforced.
The technical nature of this vulnerability can be categorized under CWE-693, which deals with Protection Mechanism Failure, specifically focusing on inadequate enforcement of navigation policies. The flaw allows attackers to craft malicious HTML pages that exploit the browser's navigation handling mechanisms, potentially enabling unauthorized redirects or access to restricted resources. The vulnerability occurs at the policy enforcement layer where Chrome's security model fails to properly validate or restrict navigation operations initiated through crafted web content. This represents a fundamental breakdown in the browser's security architecture where the expected boundaries for navigation behavior are bypassed through carefully constructed HTML elements.
The operational impact of this vulnerability extends beyond simple navigation bypass, creating potential vectors for more sophisticated attacks including phishing, credential theft, and unauthorized access to sensitive resources. Remote attackers can leverage this flaw to redirect users to malicious sites without proper authentication or authorization checks, effectively undermining the browser's security model. The iOS platform context adds additional complexity since mobile browsers face unique constraints and security considerations compared to desktop environments. This vulnerability could enable attackers to manipulate user sessions, access restricted web applications, or redirect users to sites designed to harvest sensitive information. The attack surface is particularly concerning given that iOS users may have elevated trust in browser-based applications and services.
Mitigation strategies for CVE-2021-21205 primarily involve immediate updates to Chrome on iOS platforms to version 90.0.4430.72 or later, which contains the necessary patches to address the navigation policy enforcement issues. Organizations should implement comprehensive patch management protocols to ensure all affected iOS devices receive updates promptly. Browser administrators should also consider implementing additional network-level controls and content filtering measures to detect and block potentially malicious navigation attempts. The vulnerability's classification under ATT&CK technique T1071.004 for application layer protocol: DNS indicates that network monitoring should include inspection of DNS resolution patterns that might indicate malicious navigation attempts. Security teams should also conduct regular vulnerability assessments focusing on browser security policies and navigation handling mechanisms to identify similar enforcement gaps in other browser implementations or web applications.