CVE-2019-13727 in Chrome
Summary
by MITRE
Insufficient policy enforcement in WebSockets in Google Chrome prior to 79.0.3945.79 allowed a remote attacker to bypass same origin policy via a crafted HTML page.
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Analysis
by VulDB Data Team • 03/09/2024
The vulnerability identified as CVE-2019-13727 represents a critical security flaw in Google Chrome's WebSocket implementation that fundamentally compromised the browser's same origin policy enforcement mechanisms. This weakness existed in Chrome versions prior to 79.0.3945.79 and enabled malicious actors to exploit the WebSocket protocol's security model through carefully crafted web pages. The issue stems from insufficient validation of cross-origin requests within the WebSocket communication framework, creating a pathway for unauthorized data access and potential privilege escalation attacks.
The technical root cause of this vulnerability lies in the improper handling of WebSocket connections when they originate from different domains or origins than the requesting page. When a web page attempts to establish a WebSocket connection to a server, the browser should enforce strict same origin policy checks to prevent unauthorized cross-origin communication. However, in affected Chrome versions, the implementation failed to properly validate these cross-origin requests, allowing attackers to establish connections to resources that should have been restricted by origin-based security policies. This flaw specifically affected the WebSocket API's handling of connection establishment and subsequent communication protocols.
The operational impact of CVE-2019-13727 extends beyond simple policy bypass scenarios, as it enabled sophisticated attack vectors that could compromise user data and system integrity. Remote attackers could craft malicious HTML pages that, when loaded in a victim's browser, would establish unauthorized WebSocket connections to internal services or resources that should have been protected by the same origin policy. This capability could lead to data exfiltration, privilege escalation, and potential lateral movement within network environments where WebSocket connections are used for internal communications. The vulnerability particularly affected scenarios where WebSocket connections were used for real-time data exchange between web applications and backend services, creating opportunities for attackers to intercept sensitive communications.
Security researchers have classified this vulnerability under CWE-284, which addresses improper access control mechanisms, and it aligns with ATT&CK techniques related to privilege escalation and credential access through web-based attacks. The flaw demonstrates how seemingly benign web protocols can be exploited when underlying security controls are insufficiently implemented. Organizations running affected Chrome versions faced significant risk exposure, particularly in environments where WebSocket connections were used for sensitive data transmission or where internal network boundaries relied on browser-based security controls. The vulnerability highlighted the critical importance of proper cross-origin resource sharing implementation and the need for robust enforcement of security policies in modern web browsers.
Mitigation strategies for CVE-2019-13727 primarily focus on immediate browser updates to versions 79.0.3945.79 or later where the vulnerability has been patched. System administrators should also implement additional network-level controls and monitoring to detect unauthorized WebSocket connections, particularly those that attempt to connect to internal services from external web pages. Organizations should conduct security assessments of their web applications to identify potential reliance on WebSocket connections that could be exploited through similar vulnerabilities. The patch addresses the core enforcement mechanism by strengthening the same origin policy checks during WebSocket connection establishment and ensuring that all cross-origin requests are properly validated before granting access to network resources.