CVE-2020-6561 in Chrome
Summary
by MITRE
Inappropriate implementation in Content Security Policy in Google Chrome prior to 85.0.4183.83 allowed a remote attacker to leak cross-origin data via a crafted HTML page.
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Analysis
by VulDB Data Team • 09/22/2020
The vulnerability identified as CVE-2020-6561 represents a critical flaw in Google Chrome's implementation of Content Security Policy mechanisms that governed cross-origin data protection. This weakness existed in Chrome versions prior to 85.0.4183.83 and enabled remote attackers to exploit improper handling of content security policies when processing crafted HTML pages. The flaw specifically manifested in how Chrome interpreted and enforced CSP directives when dealing with cross-origin resources, creating an avenue for unauthorized data leakage.
The technical implementation error stemmed from Chrome's Content Security Policy engine failing to properly validate or restrict access to cross-origin data when processing maliciously constructed HTML content. This vulnerability exploited the gap between the intended security model of CSP and its actual implementation, allowing attackers to bypass intended security boundaries. The flaw specifically affected how Chrome handled certain CSP directives when processing resources from different origins, creating a path for data exfiltration that should have been prevented by the security policy enforcement mechanisms.
The operational impact of this vulnerability was significant as it allowed remote attackers to perform cross-origin data leakage attacks without requiring any privileged access or user interaction beyond visiting a malicious webpage. Attackers could craft HTML pages that would trigger the flawed CSP implementation, enabling them to access and exfiltrate sensitive data from cross-origin resources that should have been protected by security policies. This capability undermined the fundamental security assumptions of web applications relying on Content Security Policy for cross-origin protection.
This vulnerability aligns with CWE-693, which addresses Protection Mechanism Failure, specifically concerning Content Security Policy implementation flaws that allow bypassing security controls. The attack vector corresponds to techniques described in the ATT&CK framework under T1071.004 for Application Layer Protocol: DNS and T1566 for Phishing, as attackers could leverage this flaw through malicious web pages to gather sensitive information from cross-origin sources. The vulnerability demonstrates a classic case of inadequate input validation and improper security enforcement where the browser's security model failed to properly isolate cross-origin resources.
Organizations should immediately update their Chrome browsers to version 85.0.4183.83 or later to mitigate this vulnerability. Additionally, security teams should implement network monitoring to detect potential exploitation attempts and review existing Content Security Policy implementations to ensure they properly account for cross-origin resource access. Browser vendors should conduct thorough security reviews of CSP implementations and consider implementing additional safeguards to prevent similar flaws in future releases.