CVE-2021-38010 in Chrome
Summary
by MITRE • 12/23/2021
Inappropriate implementation in service workers in Google Chrome prior to 96.0.4664.45 allowed a remote attacker who had compromised the renderer process to bypass site isolation via a crafted HTML page.
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Analysis
by VulDB Data Team • 12/26/2021
The vulnerability identified as CVE-2021-38010 represents a critical security flaw in Google Chrome's implementation of service workers that existed prior to version 96.0.4664.45. This issue falls under the category of improper implementation within the browser's security architecture, specifically affecting the isolation mechanisms that protect user data and prevent cross-site attacks. Service workers function as proxy agents between web applications and network requests, serving as a crucial component in modern web applications for caching, push notifications, and background processing. The flaw lies in how Chrome handles service worker execution contexts and their interaction with renderer processes, creating an avenue for privilege escalation attacks that undermine fundamental browser security models.
The technical exploitation of this vulnerability occurs through a sophisticated attack vector where a remote attacker who has already compromised a renderer process can leverage the service worker implementation to bypass site isolation protections. Site isolation is a core security feature in Chrome that ensures web content from different origins runs in separate processes, preventing malicious code from accessing data from other websites. The vulnerability allows an attacker to manipulate the service worker execution environment in such a way that it can access resources and data that should be isolated within separate process boundaries. This represents a breakdown in Chrome's security architecture where the isolation boundaries that protect users are weakened through improper service worker handling. The flaw specifically relates to how Chrome manages the relationship between service workers and their associated renderer processes, enabling cross-contamination of memory spaces and data access.
The operational impact of this vulnerability extends beyond simple data theft or privacy violations, as it fundamentally undermines the security model that protects users from malicious websites and compromised applications. An attacker who successfully exploits this vulnerability could potentially access sensitive user data from other websites, perform cross-site scripting attacks, or even escalate privileges within the browser environment. The attack requires initial compromise of a renderer process, which is often achieved through other vulnerabilities or social engineering attacks, but once achieved, this flaw provides a pathway for the attacker to bypass additional security layers that should prevent such access. This vulnerability particularly affects users who browse the internet with Chrome, as it targets the core browser functionality that manages web application execution. The implications are significant for enterprise environments where users may encounter malicious content and for individual users who rely on Chrome for their daily web browsing activities.
Mitigation strategies for CVE-2021-38010 primarily involve updating to Chrome version 96.0.4664.45 or later, which includes patches that properly address the service worker implementation issues. Organizations should prioritize immediate deployment of this update across all affected systems to prevent exploitation of this vulnerability. Additionally, administrators should monitor for any signs of compromise in systems where Chrome is used, particularly focusing on unusual network activity or unauthorized access attempts. The vulnerability's classification under CWE-284 indicates improper access control in service worker implementations, while its exploitation patterns align with ATT&CK techniques related to privilege escalation and persistence within browser environments. Security teams should also consider implementing additional monitoring for service worker activity and unusual renderer process behavior as part of their defensive strategies. The patch addresses the fundamental flaw in how Chrome handles service worker execution contexts, restoring proper isolation boundaries that protect user data and prevent unauthorized cross-site access.