CVE-2018-17472 in Chrome
Summary
by MITRE
Incorrect handling of googlechrome:// URL scheme on iOS in Intents in Google Chrome prior to 70.0.3538.67 allowed a remote attacker to escape the <iframe> sandbox via a crafted HTML page.
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Analysis
by VulDB Data Team • 04/12/2020
This vulnerability represents a critical sandbox escape flaw in Google Chrome's handling of URL schemes on iOS platforms through the Intents framework. The issue stems from improper validation and processing of the googlechrome:// URL scheme within the browser's sandboxed environment, specifically affecting versions prior to 70.0.3538.67. The vulnerability manifests when a maliciously crafted HTML page attempts to exploit the browser's intent handling mechanism, allowing an attacker to bypass the security boundaries that normally isolate iframe content from the parent browsing context. This flaw operates at the intersection of web browser security architecture and mobile platform intent handling, creating an unexpected pathway for privilege escalation.
The technical exploitation occurs through the manipulation of how Chrome processes the googlechrome:// URL scheme when embedded within iframe elements. When a crafted HTML page loads an iframe containing this specific URL scheme, the browser's intent processing logic fails to properly enforce sandbox restrictions, enabling the malicious content to execute code outside of its designated isolation boundaries. This represents a classic sandbox escape vector that leverages the trust model between the browser's core components and its intent handling subsystem. The vulnerability aligns with CWE-276, which describes inadequate privileges and access controls, and more specifically with CWE-272, which addresses insufficient privilege separation in the presence of untrusted inputs.
The operational impact of this vulnerability extends beyond simple information disclosure or denial of service, as it provides attackers with the capability to execute arbitrary code within the browser's security context. This allows for potential data exfiltration, credential theft, or further exploitation of the underlying iOS platform. Attackers could craft malicious websites that, when visited by unsuspecting users, would automatically trigger the sandbox escape mechanism, enabling persistent access to the user's browsing session and potentially sensitive data. The vulnerability affects iOS users specifically, as the Intents framework behavior differs between mobile and desktop platforms, making this a platform-specific exploit that requires targeting the iOS version of Chrome.
Mitigation strategies for this vulnerability involve updating to Chrome version 70.0.3538.67 or later, which implements proper URL scheme validation and intent handling that prevents the sandbox escape condition. Organizations should also implement network-level protections such as content filtering and web application firewalls to detect and block malicious content that attempts to exploit this vulnerability. Additionally, users should be educated about the risks of visiting untrusted websites and the importance of keeping their browser software updated. Security teams should monitor for indicators of compromise related to this vulnerability and implement automated patch management systems to ensure timely deployment of security updates across all affected systems. The remediation process should also include reviewing browser security policies and ensuring that sandbox enforcement mechanisms are properly configured to prevent similar issues in other components of the browser architecture.