CVE-2021-30612 in Chrome
Summary
by MITRE • 09/04/2021
Use after free in WebRTC in Google Chrome on Linux, ChromeOS prior to 93.0.4577.63 allowed an attacker who convinced a user to install a malicious extension to potentially exploit heap corruption via a crafted HTML page.
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Analysis
by VulDB Data Team • 09/09/2021
This vulnerability represents a critical use-after-free flaw in the WebRTC implementation within Google Chrome browsers running on Linux and ChromeOS platforms. The issue arises from improper memory management during WebRTC session handling, specifically when processing maliciously crafted HTML content that triggers the execution of vulnerable code paths. The vulnerability is particularly concerning because it can be exploited through a malicious browser extension installation, which means attackers can leverage social engineering tactics to convince users to install harmful extensions that subsequently trigger the heap corruption. The flaw exists in the way Chrome handles memory allocation and deallocation during WebRTC operations, creating a window where freed memory can be accessed and manipulated by malicious code, leading to potential arbitrary code execution. This type of vulnerability falls under the CWE-416 category, which specifically addresses use-after-free conditions, and aligns with ATT&CK technique T1173 for exploiting web browsers. The vulnerability affects all versions of Chrome prior to 93.0.4577.63, making it particularly dangerous as it could have been exploited in the wild for an extended period. The heap corruption aspect of this vulnerability means that attackers could potentially overwrite critical memory structures, allowing for privilege escalation or complete system compromise.
The operational impact of CVE-2021-30612 extends beyond simple browser exploitation as it represents a sophisticated attack vector that combines multiple security weaknesses. Attackers can leverage the browser extension installation process as a delivery mechanism, which is particularly effective because users often trust extensions from official stores and may not carefully review permissions. When a malicious extension is installed, it can trigger WebRTC functionality through crafted HTML pages that contain malicious JavaScript code. The vulnerability specifically impacts Linux and ChromeOS environments, which are often used in enterprise settings and by users who may have higher privileges or access to sensitive systems. The exploitation chain requires the user to install a malicious extension, which then loads a crafted HTML page that triggers the WebRTC code path, ultimately leading to heap corruption. This vulnerability demonstrates the complexity of modern browser security, where a flaw in a single component can potentially lead to complete system compromise. The issue is particularly dangerous in enterprise environments where users may have elevated privileges or access to critical infrastructure, making the potential impact significantly higher than typical browser vulnerabilities.
Mitigation strategies for CVE-2021-30612 must address both the immediate patching requirements and broader security hygiene practices. The primary and most effective mitigation is updating to Chrome version 93.0.4577.63 or later, which contains the necessary memory management fixes to prevent the use-after-free condition. Organizations should implement strict browser extension policies, including mandatory review processes for all extensions and the use of automated tools to detect potentially malicious extensions. Network administrators should consider implementing browser hardening measures such as disabling unnecessary WebRTC functionality in environments where it is not required. The vulnerability also highlights the importance of user education and awareness training, particularly around the risks of installing unknown browser extensions. Security teams should monitor for indicators of compromise related to malicious extensions and implement network-based detection measures to identify potential exploitation attempts. Additional mitigations include implementing strict content security policies, using browser sandboxing features, and maintaining up-to-date threat intelligence feeds to identify new malicious extensions. The vulnerability also underscores the necessity of regular security assessments and penetration testing to identify similar memory corruption issues in other browser components or third-party libraries. Organizations should also consider implementing automated patch management systems to ensure timely deployment of security updates across all affected systems. Given the nature of the vulnerability and its potential for privilege escalation, enterprises should also review their access control policies and implement principle of least privilege practices to limit the potential impact of successful exploitation.