CVE-2021-21171 in Edge
Summary
by MITRE • 03/10/2021
Incorrect security UI in TabStrip and Navigation in Google Chrome on Android prior to 89.0.4389.72 allowed a remote attacker to spoof the contents of the Omnibox (URL bar) via a crafted HTML page.
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Analysis
by VulDB Data Team • 03/29/2021
The vulnerability CVE-2021-21171 represents a critical security flaw in Google Chrome's user interface implementation on Android devices, specifically affecting versions prior to 89.0.4389.72. This issue resides within the TabStrip and Navigation components of the browser's interface, where the security warning mechanisms fail to properly validate or display critical information about web page origins and security status. The flaw operates at the intersection of user interface security and web browser architecture, where the visual indicators that should protect users from malicious websites become unreliable.
The technical implementation of this vulnerability stems from insufficient validation of security indicators within Chrome's navigation bar elements. When a user navigates to a crafted HTML page, the browser's Omnibox display fails to accurately represent the actual security context of the visited site. This allows attackers to manipulate the visual appearance of the URL bar to display misleading information about the website's authenticity and security status. The vulnerability specifically affects how Chrome handles security UI elements during page transitions and navigation events, creating a window where malicious actors can exploit the browser's trust model.
This security flaw has significant operational impact as it directly undermines the fundamental security model that users rely on when browsing the web. Users may be deceived into believing they are visiting legitimate websites when they are actually interacting with malicious content, potentially leading to credential theft, financial fraud, or data exfiltration. The vulnerability operates in a way that bypasses traditional security mechanisms, as it exploits the very interface elements designed to protect users from such threats. Attackers can craft HTML pages that manipulate the visual feedback provided by Chrome's security indicators, effectively creating a form of UI redressing attack that targets user trust and security awareness.
The flaw aligns with CWE-693, which addresses Protection Mechanism Failure, specifically in the context of user interface security controls. From an adversarial perspective, this vulnerability maps to several ATT&CK techniques including T1059 for user execution of malicious content and T1566 for credential access through social engineering. The attack vector requires a remote web page to be loaded, making it particularly dangerous in phishing campaigns or when users are browsing untrusted websites. The vulnerability demonstrates how interface-level security mechanisms can be subverted to create a false sense of security, which is particularly concerning in mobile environments where users may be less vigilant about security warnings.
Mitigation strategies should focus on immediate browser updates to version 89.0.4389.72 or later, which contains the necessary patches to restore proper security UI validation. Users should also maintain awareness of their browser's security indicators and verify website authenticity through multiple means beyond visual cues alone. Organizations should implement browser hardening policies and consider additional security layers such as content filtering and security extensions to provide defense in depth. The vulnerability serves as a reminder of the critical importance of user interface security controls and the need for comprehensive security validation at all levels of browser implementation, from core rendering engines to visual presentation components.