CVE-2018-6099 in Chrome
Summary
by MITRE
A lack of CORS checks in Blink in Google Chrome prior to 66.0.3359.106 allowed a remote attacker to leak limited cross-origin data via a crafted HTML page.
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Analysis
by VulDB Data Team • 06/13/2023
The vulnerability identified as CVE-2018-6099 represents a critical security flaw in the Blink rendering engine that powers Google Chrome and other Chromium-based browsers. This issue stems from insufficient Cross-Origin Resource Sharing (CORS) validation mechanisms within the browser's core components, creating a pathway for malicious actors to exploit cross-origin data leakage. The vulnerability specifically affects Chrome versions prior to 66.0.3359.106, making it a significant concern for users operating outdated browser versions. The flaw exists at the fundamental level of how browsers handle cross-origin requests, potentially allowing unauthorized data access that could compromise user privacy and system security.
The technical nature of this vulnerability involves the bypass of CORS policy enforcement within Blink's implementation, enabling remote attackers to craft malicious HTML pages that can access cross-origin resources without proper authorization. This occurs because the browser fails to adequately validate the origin of requests, allowing malicious sites to perform operations that should be restricted based on cross-origin policies. The flaw operates by exploiting the browser's handling of certain HTTP headers and request validation processes, where the CORS preflight checks are either omitted or improperly enforced. This creates an attack surface where sensitive data can be accessed across domain boundaries without the proper security constraints that should normally be in place.
From an operational perspective, this vulnerability poses substantial risks to users and organizations as it enables sophisticated cross-origin data leakage attacks. Attackers can leverage this flaw to access cookies, session tokens, and other sensitive information stored in cross-origin contexts, potentially leading to session hijacking, credential theft, and unauthorized access to protected resources. The impact extends beyond simple data exposure, as it can facilitate more complex attacks including privilege escalation and lateral movement within network environments. The remote nature of the attack means that users can be compromised simply by visiting malicious websites, making this vulnerability particularly dangerous in phishing campaigns and targeted attacks. The vulnerability aligns with CWE-346, which addresses "Origin Validation Error" in security contexts, and maps to ATT&CK technique T1071.001 for Application Layer Protocol: Web Protocols, demonstrating how web-based attacks can exploit browser implementation flaws.
The mitigation strategies for CVE-2018-6099 primarily focus on updating to the patched version of Google Chrome 66.0.3359.106 or later, which implements proper CORS validation mechanisms. Organizations should prioritize immediate deployment of browser updates across all systems to eliminate exposure to this vulnerability. Additionally, network administrators can implement additional security controls such as Content Security Policy (CSP) headers, which can provide an additional layer of protection against cross-origin attacks by restricting how resources can be loaded and executed. Browser security configurations should also be reviewed to ensure that CORS policies are properly enforced at the organizational level. Regular security assessments and vulnerability scanning should be conducted to identify any remaining exposure points, while user education about safe browsing practices remains crucial in preventing exploitation through social engineering attacks that might leverage this vulnerability. The remediation process should include monitoring for any signs of exploitation attempts and maintaining up-to-date threat intelligence to detect potential related attacks targeting similar browser implementation flaws.