CVE-2016-1682 in Chrome
Summary
by MITRE
The ServiceWorkerContainer::registerServiceWorkerImpl function in WebKit/Source/modules/serviceworkers/ServiceWorkerContainer.cpp in Blink, as used in Google Chrome before 51.0.2704.63, allows remote attackers to bypass the Content Security Policy (CSP) protection mechanism via a ServiceWorker registration.
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Analysis
by VulDB Data Team • 08/22/2022
The vulnerability identified as CVE-2016-1682 represents a critical security flaw in the WebKit rendering engine's implementation of ServiceWorker functionality within Google Chrome browsers. This issue specifically affects versions prior to 51.0.2704.63 and stems from improper handling of Content Security Policy enforcement during ServiceWorker registration processes. The flaw exists in the ServiceWorkerContainer::registerServiceWorkerImpl function located in WebKit/Source/modules/serviceworkers/ServiceWorkerContainer.cpp, which is part of the Blink rendering engine that powers Chrome and other Chromium-based browsers. The vulnerability allows remote attackers to bypass Content Security Policy protections that are designed to prevent malicious code execution and restrict resource loading.
The technical implementation flaw occurs when the ServiceWorker registration process fails to properly validate or enforce Content Security Policy directives during the registration phase. ServiceWorkers are background processes that can intercept and handle network requests, cache resources, and manage push notifications for web applications. When a web application attempts to register a ServiceWorker, the browser should enforce the site's CSP policies to prevent unauthorized resource loading or script execution. However, this vulnerability enables attackers to register ServiceWorkers that can bypass these security restrictions, effectively allowing malicious code to execute outside the normal CSP boundaries. The flaw demonstrates a weakness in the security model where the registration process does not properly validate the security context or enforce policy restrictions that should normally apply to the ServiceWorker's execution environment.
The operational impact of this vulnerability is significant as it allows attackers to circumvent fundamental web security protections that are essential for preventing cross-site scripting attacks, malicious resource loading, and other code injection scenarios. When exploited, the vulnerability enables attackers to register ServiceWorkers that can access resources, make network requests, and potentially exfiltrate data without being constrained by the website's Content Security Policy. This creates a persistent threat vector where malicious ServiceWorkers can operate in the background, potentially accessing sensitive user data, intercepting communications, or performing actions that would normally be blocked by CSP. The vulnerability affects all web applications that rely on Content Security Policy for protection, making it particularly dangerous in environments where users may encounter malicious websites or where applications handle sensitive data.
This vulnerability maps to CWE-284 Access Control Bypass and aligns with several ATT&CK techniques including T1190 Exploit Public-Facing Application and T1059 Command and Scripting Interpreter. The attack surface extends beyond simple CSP bypass to include potential privilege escalation and persistent threat capabilities. Organizations should prioritize updating affected Chrome installations to version 51.0.2704.63 or later, as this represents the official fix for the vulnerability. Additional mitigations include implementing proper monitoring for unauthorized ServiceWorker registrations, conducting security audits of web applications that utilize ServiceWorkers, and ensuring that Content Security Policy directives are properly configured and enforced. The vulnerability highlights the importance of comprehensive security testing for web platform features and demonstrates how seemingly benign functionality can introduce critical security gaps when not properly integrated with existing security mechanisms.