CVE-2018-6150 in Chrome
Summary
by MITRE
Incorrect handling of CORS in ServiceWorker in Google Chrome prior to 66.0.3359.117 allowed a remote attacker to leak cross-origin data via a crafted HTML page.
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Analysis
by VulDB Data Team • 07/17/2024
The vulnerability identified as CVE-2018-6150 represents a critical security flaw in Google Chrome's implementation of Cross-Origin Resource Sharing (CORS) within ServiceWorker contexts. This issue affected Chrome versions prior to 66.0.3359.117 and enabled remote attackers to exploit improper CORS handling mechanisms, creating a pathway for unauthorized data leakage across origin boundaries. The flaw specifically targeted the ServiceWorker API's interaction with CORS policies, which are fundamental to web security and prevent malicious sites from accessing resources protected by cross-origin restrictions.
The technical root cause of this vulnerability lies in the inadequate validation and enforcement of CORS policies when ServiceWorker intercepts network requests. ServiceWorkers operate as proxy agents between web applications and network resources, capable of intercepting and modifying fetch requests. In the affected Chrome versions, the CORS validation logic failed to properly enforce security boundaries when ServiceWorkers processed cross-origin requests, allowing malicious actors to craft HTML pages that could trigger unintended data leakage. This misconfiguration occurred during the request interception phase where ServiceWorker would process requests without adequate CORS header verification, potentially exposing sensitive data from different origins.
The operational impact of this vulnerability extends beyond simple data leakage, as it fundamentally undermines the browser's security model and cross-origin protection mechanisms. Attackers could exploit this weakness by creating malicious web pages that leverage ServiceWorker to make cross-origin requests, potentially accessing cookies, authentication tokens, or other sensitive information from legitimate websites. The vulnerability is particularly dangerous because it operates at the browser level, bypassing traditional web application security controls and potentially affecting any website that relies on ServiceWorker for functionality. This type of attack falls under the attack technique category of credential access and data exfiltration as outlined in the MITRE ATT&CK framework, specifically targeting the web application layer.
The security implications of CVE-2018-6150 align with CWE-346, which addresses improper verification of data source authenticity, and CWE-200, concerning exposure of sensitive information. This vulnerability demonstrates how browser security mechanisms can be circumvented when underlying API implementations fail to properly enforce security policies. The flaw represents a failure in the principle of least privilege, where ServiceWorker contexts were granted unnecessary access to cross-origin resources without proper authorization checks. Organizations relying on Chrome-based applications face significant risk, as this vulnerability could enable attackers to perform reconnaissance and gather sensitive information from users' browsing sessions, potentially leading to session hijacking or more sophisticated attacks. The remediation approach required updating Chrome to version 66.0.3359.117 or later, which included corrected CORS handling within ServiceWorker contexts, ensuring proper enforcement of cross-origin security policies.
This vulnerability highlights the complexity of modern web security implementations and the challenges of maintaining proper isolation between different browser components. The integration of ServiceWorkers with CORS mechanisms requires careful attention to ensure that the proxy nature of ServiceWorkers does not inadvertently weaken security boundaries. The incident underscores the importance of thorough security testing for browser APIs and the need for continuous monitoring of security updates, particularly for core browser components that handle network requests and security policies. The attack vector demonstrates how seemingly benign browser features can become attack surfaces when security boundaries are not properly maintained, emphasizing the need for comprehensive security architectures that consider all potential interaction points between different web technologies and security mechanisms.