CVE-2016-5173 in Chrome
Summary
by MITRE
The extensions subsystem in Google Chrome before 53.0.2785.113 does not properly restrict access to Object.prototype, which allows remote attackers to load unintended resources, and consequently trigger unintended JavaScript function calls and bypass the Same Origin Policy via an indirect interception attack.
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Analysis
by VulDB Data Team • 09/19/2022
The vulnerability identified as CVE-2016-5173 resides within the extensions subsystem of Google Chrome browser version 53.0.2785.113 and earlier. This flaw represents a critical security weakness that stems from improper access controls within the JavaScript object model, specifically targeting Object.prototype. The extensions subsystem in Chrome is designed to provide additional functionality through third-party add-ons, but this particular vulnerability creates a pathway for malicious actors to exploit the underlying JavaScript engine's object handling mechanisms. The flaw manifests when the browser fails to adequately enforce access restrictions on prototype objects, allowing attackers to manipulate the JavaScript execution environment in unexpected ways.
The technical implementation of this vulnerability involves an indirect interception attack that leverages the prototype chain mechanism within JavaScript. When Chrome processes extension-related code, it does not properly validate or restrict access to Object.prototype properties, enabling attackers to intercept and redirect resource loading operations. This misconfiguration allows remote adversaries to inject malicious code that can manipulate the execution flow, effectively bypassing the fundamental Same Origin Policy that normally prevents web pages from accessing resources from different domains. The attack exploits the way Chrome handles JavaScript object inheritance and prototype manipulation, creating a scenario where unintended resource loading occurs through the prototype chain rather than through normal execution paths.
The operational impact of this vulnerability extends beyond simple resource loading manipulation to encompass broader security implications within the browser's sandboxed environment. Attackers can leverage this weakness to execute unintended JavaScript functions that would normally be restricted, potentially leading to full browser compromise or data exfiltration. The bypass of the Same Origin Policy creates an avenue for cross-site scripting attacks where malicious extensions or compromised websites can access resources they should not be able to reach. This vulnerability particularly affects users running older versions of Chrome where the security patches have not been applied, making it a significant concern for organizations with outdated browser deployments.
Mitigation strategies for CVE-2016-5173 primarily focus on immediate browser updates to version 53.0.2785.113 or later, which contain the necessary patches to properly enforce access controls on Object.prototype. Organizations should implement comprehensive patch management policies to ensure all Chrome installations are updated promptly. Additionally, security teams should monitor for suspicious extension behavior and implement strict extension approval processes for enterprise environments. From a defensive perspective, this vulnerability aligns with CWE-284, which addresses improper access control, and maps to ATT&CK technique T1059.007 for JavaScript execution. Network-level defenses should include monitoring for unusual resource loading patterns and implementing web application firewalls that can detect and block prototype manipulation attempts. The remediation process should also include user education regarding the risks of installing untrusted extensions and the importance of keeping browser software current with security patches.