CVE-2019-5830 in Chrome
Summary
by MITRE
Insufficient policy enforcement in CORS in Google Chrome prior to 75.0.3770.80 allowed a remote attacker to leak cross-origin data via a crafted HTML page.
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Analysis
by VulDB Data Team • 06/24/2024
The vulnerability identified as CVE-2019-5830 represents a critical flaw in Google Chrome's implementation of Cross-Origin Resource Sharing (CORS) policy enforcement mechanisms. This issue affected Chrome versions prior to 75.0.3770.80 and exposed a fundamental weakness in how the browser handled cross-origin requests, particularly when processing crafted HTML content. The flaw essentially allowed malicious actors to bypass intended security boundaries that should have prevented unauthorized data access between different origins, creating a significant attack surface for remote exploitation.
The technical root cause of this vulnerability lies in Chrome's insufficient validation of CORS policies when processing specific HTML constructs that trigger cross-origin resource requests. When a malicious website loaded in a browser window attempted to access resources from a different origin, the browser's CORS implementation failed to properly enforce the security restrictions that should have been applied. This weakness was particularly dangerous because it could be exploited through carefully crafted HTML pages that leveraged the browser's rendering engine to initiate cross-origin requests without proper authorization checks. The vulnerability essentially created a bypass mechanism that allowed attackers to perform unauthorized data leakage operations across domain boundaries.
The operational impact of this vulnerability extends far beyond simple data theft, as it fundamentally undermines the security model that web browsers rely upon for protecting user data. Attackers could exploit this flaw to access sensitive information from trusted domains, potentially including authentication tokens, personal data, or confidential business information stored on servers that should have been protected by CORS policies. The remote nature of this attack means that users could be compromised simply by visiting a malicious website, making it particularly dangerous in phishing campaigns or drive-by download scenarios. This vulnerability directly violates the core principle of web security that prevents unauthorized cross-origin access to resources, creating a persistent threat vector that could be leveraged for extended surveillance or data exfiltration operations.
The mitigation for this vulnerability required immediate patching of Chrome browsers to version 75.0.3770.80 or later, which included enhanced CORS policy enforcement mechanisms. Organizations should have implemented browser update policies to ensure all users were running patched versions. Additional defensive measures included network monitoring for suspicious cross-origin requests and enhanced web application security controls to detect and prevent exploitation attempts. This vulnerability aligns with CWE-346, which addresses "Origin Validation Error", and maps to ATT&CK technique T1071.001 for application layer protocol: web protocols, demonstrating how browser-based vulnerabilities can be leveraged for broader attack chains. Security teams should have also reviewed their incident response procedures to address potential exploitation and implemented proper browser hardening configurations to minimize the attack surface. The vulnerability highlighted the importance of continuous security testing and validation of browser security features, particularly those related to web standards implementation that form the foundation of modern web security.