CVE-2016-5193 in Chrome
Summary
by MITRE
Google Chrome prior to 54.0 for iOS had insufficient validation of URLs for windows open by DOM, which allowed a remote attacker to bypass restrictions on navigation to certain URL schemes via crafted HTML pages.
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Analysis
by VulDB Data Team • 10/12/2022
The vulnerability identified as CVE-2016-5193 represents a significant security flaw in Google Chrome versions prior to 54.0 on iOS platforms, specifically concerning the handling of URL validation within the Document Object Model. This weakness stems from inadequate input sanitization mechanisms that govern how the browser processes and validates URLs when windows are opened through DOM methods. The issue manifests in the browser's failure to properly validate URL schemes, creating an avenue for malicious actors to exploit navigation restrictions that should otherwise prevent access to sensitive or restricted protocols.
The technical implementation of this vulnerability lies in the insufficient validation logic within Chrome's iOS browser engine, particularly when processing DOM-based window.open() operations. Attackers could craft malicious HTML pages containing specially formatted URLs that would bypass the normal security checks designed to prevent navigation to restricted schemes such as file://, data:, or other potentially dangerous protocols. This flaw operates at the intersection of web security boundaries where DOM manipulation intersects with URL handling, creating a pathway for unauthorized navigation that should have been blocked by the browser's security model. The vulnerability essentially allows for a bypass of the browser's scheme validation mechanisms, enabling attackers to redirect users to arbitrary locations without proper authorization checks.
From an operational perspective, this vulnerability presents a substantial risk to iOS users of affected Chrome versions, as it enables remote code execution through social engineering attacks. Attackers could construct malicious websites that, when visited by unsuspecting users, would automatically navigate to restricted URL schemes that could potentially access local files or execute malicious code. The impact extends beyond simple navigation bypass, as it could enable attackers to access device resources, steal sensitive information, or redirect users to phishing sites. This vulnerability particularly affects mobile users who rely on Chrome for iOS, as the mobile browser environment often has different security considerations and attack surface compared to desktop implementations.
The security implications of CVE-2016-5193 align with CWE-20, which describes improper input validation, and can be mapped to ATT&CK technique T1059.001 for command and scripting interpreter usage, as well as T1190 for exploit for client execution. The vulnerability demonstrates how insufficient validation can create persistent security gaps that attackers can leverage across multiple attack vectors. Organizations and users should implement immediate mitigations including updating to Chrome version 54.0 or later, which includes proper URL scheme validation and enhanced DOM handling security measures. Additionally, administrators should consider implementing web content filtering solutions and user education programs to reduce exposure to malicious websites that could exploit this vulnerability. The fix implemented by Google involved strengthening the URL validation logic within the DOM navigation handling code, ensuring that all URL schemes are properly checked against allowed protocols before any navigation occurs, thereby closing the security gap that previously allowed bypass of navigation restrictions.