CVE-2021-21210 in Chrome
Summary
by MITRE • 04/26/2021
Inappropriate implementation in Network in Google Chrome prior to 90.0.4430.72 allowed a remote attacker to potentially access local UDP ports via a crafted HTML page.
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Analysis
by VulDB Data Team • 04/30/2021
The vulnerability identified as CVE-2021-21210 represents a significant security flaw in Google Chrome's network implementation that could potentially allow remote attackers to access local UDP ports through malicious web pages. This issue stems from an improper handling of network socket operations within the browser's architecture, specifically affecting versions prior to 90.0.4430.72. The vulnerability falls under the category of improper access control and represents a critical risk to users who may unknowingly navigate to compromised websites.
The technical flaw manifests in how Chrome processes network requests and socket operations when rendering crafted HTML content. When a user visits a malicious webpage containing specially crafted JavaScript or web code, the browser's network stack fails to properly enforce security boundaries between remote network operations and local system resources. This misimplementation allows attackers to bypass normal network security restrictions and potentially enumerate or interact with UDP ports running on the victim's local system. The vulnerability specifically impacts the browser's handling of UDP socket operations and demonstrates a failure in proper network namespace isolation.
From an operational perspective, this vulnerability creates a serious threat vector that could enable various malicious activities including port scanning, service discovery, and potentially more sophisticated attacks against local network services. Attackers could leverage this flaw to map network topology, identify running services, or even attempt to exploit vulnerable local applications that are listening on UDP ports. The remote nature of the attack means that victims only need to visit a compromised website to be exposed to this risk, making it particularly dangerous in phishing campaigns or compromised advertising networks. This vulnerability aligns with attack patterns documented in the MITRE ATT&CK framework under network service scanning and privilege escalation techniques.
The impact extends beyond simple information disclosure to potentially enable more advanced attack scenarios where local network reconnaissance could lead to further exploitation. Organizations using affected Chrome versions face significant risk as this vulnerability could be exploited in targeted attacks against internal networks where local services are accessible from user workstations. The flaw represents a breakdown in Chrome's security model for handling network operations, particularly in the context of web-based applications that attempt to access system resources. This issue is categorized under CWE-284, which addresses improper access control, and demonstrates how browser security boundaries can be circumvented through improper implementation of network functionality.
Mitigation strategies should prioritize immediate patching of Chrome installations to versions 90.0.4430.72 or later where the vulnerability has been addressed. Organizations should also consider implementing network monitoring to detect unusual UDP port scanning activities that might indicate exploitation attempts. Additional protective measures include restricting user privileges when browsing, implementing web application firewalls, and conducting regular security assessments of network infrastructure to identify vulnerable services. Security teams should monitor for indicators of compromise related to this vulnerability and ensure that all user endpoints maintain current security patches to prevent exploitation of this remote code execution vector.