CVE-2021-21214 in Chrome
Summary
by MITRE • 04/26/2021
Use after free in Network API in Google Chrome prior to 90.0.4430.72 allowed a remote attacker to potentially exploit heap corruption via a crafted Chrome Extension.
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Analysis
by VulDB Data Team • 04/30/2021
This vulnerability represents a critical use-after-free condition in Google Chrome's Network API component that existed prior to version 90.0.4430.72. The flaw occurs when the browser processes network-related operations within the context of a Chrome extension, creating a scenario where memory allocated to network objects becomes accessible after it has been freed from memory. This memory management error allows an attacker to potentially execute arbitrary code by manipulating the heap state through a specially crafted malicious Chrome extension. The vulnerability falls under the CWE-416 category of Use After Free, which is classified as a serious memory corruption issue that can lead to privilege escalation and remote code execution. The attack vector requires the victim to install or interact with a malicious extension, making it particularly concerning in environments where extension permissions are granted without proper scrutiny.
The technical exploitation of this vulnerability involves the manipulation of Chrome's extension architecture where network API calls are made in a manner that triggers the premature deallocation of memory objects. When the extension attempts to access these freed memory locations, the heap corruption can be leveraged to overwrite critical memory regions or redirect execution flow. This type of vulnerability is particularly dangerous because it operates within the trusted extension execution environment, potentially allowing attackers to bypass security boundaries that normally separate extension code from core browser functionality. The Network API in question handles various network operations including HTTP requests, WebSocket connections, and other networking primitives that extensions commonly utilize, making this attack surface particularly broad and impactful.
The operational impact of CVE-2021-21214 extends beyond simple remote code execution to encompass potential privilege escalation and system compromise. Attackers can exploit this vulnerability to gain unauthorized access to user data, perform man-in-the-middle attacks, or establish persistent backdoors through compromised extensions. The vulnerability affects all users running Chrome versions before 90.0.4430.72, making it a widespread concern for organizations that rely on Chrome for their web browsing needs. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation through memory corruption and execution of malicious code through browser extensions, which are commonly used in advanced persistent threat campaigns. The exploitation process typically involves crafting a malicious extension that triggers the specific code path leading to heap corruption, followed by careful manipulation of the memory layout to achieve desired execution control.
Mitigation strategies for this vulnerability primarily involve immediate patching of Chrome installations to version 90.0.4430.72 or later, which contains the necessary memory management fixes. Organizations should implement strict extension vetting processes and avoid installing extensions from untrusted sources. Browser security policies can be enhanced through configuration management to limit extension permissions and network access capabilities. Network monitoring solutions should be deployed to detect anomalous behavior patterns that may indicate exploitation attempts. Regular security assessments of browser environments and extension repositories are essential for early detection of potential threats. The vulnerability also highlights the importance of maintaining up-to-date browser security practices and implementing defense-in-depth strategies that include web application firewalls, content security policies, and user education about extension security risks. Organizations should also consider implementing browser isolation techniques and sandboxing mechanisms to limit the potential impact of successful exploitation attempts.