CVE-2013-6666 in Chrome
Summary
by MITRE
The PepperFlashRendererHost::OnNavigate function in renderer/pepper/pepper_flash_renderer_host.cc in Google Chrome before 33.0.1750.146 does not verify that all headers are Cross-Origin Resource Sharing (CORS) simple headers before proceeding with a PPB_Flash.Navigate operation, which might allow remote attackers to bypass intended CORS restrictions via an inappropriate header.
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Analysis
by VulDB Data Team • 06/15/2021
The vulnerability described in CVE-2013-6666 represents a critical security flaw in Google Chrome's handling of Cross-Origin Resource Sharing (CORS) restrictions within its Pepper Flash plugin implementation. This issue affects Chrome versions prior to 33.0.1750.146 and stems from improper validation of HTTP headers during the PPB_Flash.Navigate operation. The flaw specifically resides in the PepperFlashRendererHost::OnNavigate function located in renderer/pepper/pepper_flash_renderer_host.cc, where the application fails to enforce proper CORS header validation before executing navigation operations.
The technical nature of this vulnerability allows malicious actors to exploit a bypass mechanism in Chrome's CORS enforcement system by injecting headers that should normally be restricted. The function processes navigation requests without verifying whether all headers present in the request are classified as CORS simple headers according to web standards. This oversight enables attackers to include non-simple headers in their requests that would typically be blocked by CORS policies, effectively circumventing the security controls designed to prevent cross-origin resource access. The vulnerability operates at the renderer process level, making it particularly dangerous as it can be exploited through web-based attacks without requiring local system access.
The operational impact of this vulnerability extends beyond simple data leakage, potentially enabling sophisticated attacks such as cross-site request forgery, data exfiltration, and privilege escalation within the browser environment. Attackers could leverage this flaw to access resources that should be restricted to specific origins, potentially compromising user data and session information. The vulnerability aligns with CWE-693, which covers protection mechanism failures, and represents a specific implementation weakness in CORS validation that violates the principle of least privilege. This weakness could be exploited through various attack vectors including malicious websites, phishing campaigns, or compromised third-party content that utilizes the Flash plugin.
Mitigation strategies for this vulnerability require immediate patching of affected Chrome versions to 33.0.1750.146 or later, where Google implemented proper CORS header validation in the Pepper Flash plugin. Organizations should also consider implementing additional network-level protections such as content security policies and web application firewalls to provide defense-in-depth. The remediation process should include comprehensive testing of browser configurations and monitoring for any suspicious network traffic patterns that might indicate exploitation attempts. Security teams should also review their incident response procedures to ensure readiness for potential exploitation of this class of vulnerability, which falls under ATT&CK technique T1071.004 for application layer protocol usage and T1566 for credential harvesting through social engineering. Regular security assessments and browser hardening practices should be maintained to prevent similar issues in other browser components and plugins.