CVE-2021-30586 in Chrome
Summary
by MITRE • 08/04/2021
Use after free in dialog box handling in Windows in Google Chrome prior to 92.0.4515.107 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 • 08/07/2021
The vulnerability identified as CVE-2021-30586 represents a critical use-after-free flaw in the dialog box handling mechanism of Google Chrome running on Windows operating systems. This security weakness exists within the browser's memory management processes and specifically affects Chrome versions prior to 92.0.4515.107, creating a significant attack surface for malicious actors seeking to exploit heap corruption vulnerabilities through crafted web content. The flaw stems from improper memory deallocation handling when processing dialog box elements, allowing attackers to manipulate freed memory regions and potentially execute arbitrary code.
The technical implementation of this vulnerability involves a classic use-after-free condition where memory allocated for dialog box elements is released but not properly invalidated, enabling subsequent memory access attempts to reference already freed locations. This memory corruption scenario occurs during the processing of HTML content that triggers dialog box rendering, particularly when malicious extensions are installed and active within the browser environment. The vulnerability manifests when Chrome's JavaScript engine processes dialog-related HTML elements, leading to improper memory management that can be exploited by attackers who craft specific HTML pages designed to trigger the vulnerable code path. According to CWE-416, this represents a direct violation of memory safety principles where memory is accessed after it has been freed, creating a potential for code execution or system compromise.
From an operational perspective, this vulnerability creates a severe risk for users who may inadvertently install malicious browser extensions, as the attack vector requires only a single user interaction to potentially compromise the system. The exploit chain begins with convincing a user to install a malicious extension, which then leverages the use-after-free condition through a crafted HTML page to execute arbitrary code with the privileges of the Chrome process. This attack model aligns with ATT&CK technique T1176, which describes the use of browser extensions for persistence and privilege escalation, while also demonstrating the exploitation of browser memory corruption vulnerabilities as outlined in ATT&CK technique T1059. The vulnerability can potentially lead to full system compromise, as the Chrome process typically runs with elevated privileges, and successful exploitation could result in persistent backdoor access, data exfiltration, or further lateral movement within the compromised network.
Mitigation strategies for CVE-2021-30586 primarily focus on immediate patching of Chrome installations to version 92.0.4515.107 or later, which contains the necessary memory management fixes to prevent the use-after-free condition. Organizations should implement comprehensive browser update policies and consider deploying automated patch management systems to ensure all Chrome installations remain current with security patches. Additional defensive measures include implementing strict extension installation policies, disabling unnecessary browser extensions, and employing web filtering solutions that can block malicious HTML content before it reaches users. Network-based detection systems should monitor for suspicious HTML content patterns that may indicate attempts to exploit this vulnerability, while endpoint protection solutions should be configured to alert on unusual memory access patterns or process behavior that could indicate exploitation attempts. Security teams should also consider implementing browser hardening configurations that restrict memory access patterns and limit the potential impact of successful exploitation attempts.