CVE-2021-30571 in Chrome
Summary
by MITRE • 08/04/2021
Insufficient policy enforcement in DevTools in Google Chrome prior to 92.0.4515.107 allowed an attacker who convinced a user to install a malicious extension to potentially perform a sandbox escape via a crafted HTML page.
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Analysis
by VulDB Data Team • 08/07/2021
The vulnerability identified as CVE-2021-30571 represents a critical security flaw in Google Chrome's DevTools component that existed prior to version 92.0.4515.107. This issue stems from insufficient policy enforcement mechanisms within the browser's developer tools framework, creating a pathway for attackers to bypass security boundaries and potentially escape the sandboxed environment that normally protects Chrome's rendering engine. The vulnerability specifically targets the interaction between DevTools and malicious extensions, exploiting a weakness in how Chrome handles extension installation and execution contexts. The flaw enables attackers to craft specially designed HTML pages that can manipulate DevTools functionality to execute arbitrary code outside of the intended security boundaries.
The technical implementation of this vulnerability involves the exploitation of trust relationships between Chrome's DevTools interface and extension components. When a user installs a malicious extension, the vulnerability allows an attacker to leverage DevTools' privileged access capabilities to manipulate the browser's security model. This occurs through a combination of extension loading sequences and DevTools API interactions that fail to properly validate or restrict the execution context of loaded content. The flaw essentially creates a vector where malicious code can transition from a restricted extension environment into the broader browser sandbox, effectively undermining the isolation mechanisms that protect against cross-site scripting and other browser-based attacks. This represents a classic sandbox escape vulnerability where the boundary between trusted and untrusted code becomes porous.
The operational impact of CVE-2021-30571 extends beyond typical browser-based attacks to potentially enable more sophisticated exploitation techniques. Attackers can leverage this vulnerability to gain elevated privileges within the browser environment, potentially accessing user data, cookies, and other sensitive information stored in the browser's memory space. The vulnerability's exploitation requires user interaction through extension installation, making it a social engineering target that could be combined with phishing campaigns or drive-by downloads. The attack surface includes not only the user's browsing data but also the potential for persistent access through the compromised DevTools functionality. This vulnerability aligns with ATT&CK technique T1059.001 for command and scripting interpreter and T1547.001 for registry run keys, as it enables persistent access and command execution within the browser environment. The security implications are particularly concerning given Chrome's widespread usage and the privileged nature of DevTools functionality.
Mitigation strategies for CVE-2021-30571 focus on immediate version updates to Chrome 92.0.4515.107 or later, which contain the necessary policy enforcement fixes. Organizations should implement strict extension management policies, including mandatory review processes for all browser extensions and regular audits of installed components. Security teams should monitor for suspicious DevTools activity and implement network-level controls to detect potential exploitation attempts. Browser hardening measures including disabling unnecessary DevTools features for non-developer users and implementing strict content security policies can provide additional protection layers. The vulnerability demonstrates the importance of maintaining up-to-date browser software and highlights the risks associated with extension-based attacks that can leverage legitimate browser functionality to bypass security controls. This issue also underscores the need for continuous security monitoring and the importance of vulnerability management programs that can quickly identify and remediate such browser-based security flaws.
This vulnerability type falls under CWE-284 Access Control and represents a failure in privilege separation between browser components. The flaw demonstrates how seemingly benign developer tools can become attack vectors when proper access controls are not enforced. Security practitioners should consider this vulnerability as part of broader browser security assessments and implement comprehensive monitoring solutions that can detect unauthorized DevTools access patterns. The incident highlights the ongoing challenge of maintaining secure browser environments where legitimate developer tools must coexist with robust security controls to prevent exploitation by malicious actors.