CVE-2021-34490 in Windows
Summary
by MITRE • 07/15/2021
Windows TCP/IP Driver Denial of Service Vulnerability This CVE ID is unique from CVE-2021-31183, CVE-2021-33772.
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Analysis
by VulDB Data Team • 07/17/2021
The Windows TCP/IP driver vulnerability identified as CVE-2021-34490 represents a critical denial of service flaw that affects the core networking stack of Microsoft Windows operating systems. This vulnerability specifically targets the Transmission Control Protocol/Internet Protocol implementation within the Windows kernel, creating a condition where maliciously crafted network packets can trigger system instability and complete service disruption. Unlike related vulnerabilities such as CVE-2021-31183 and CVE-2021-33772 which focus on different aspects of the Windows networking infrastructure, CVE-2021-34490 operates at the kernel level within the TCP/IP protocol driver, making it particularly dangerous as it can compromise the fundamental network connectivity of affected systems. The vulnerability resides in how the Windows TCP/IP stack processes certain network traffic patterns, creating an exploitable condition that allows remote attackers to cause system crashes or restarts without requiring authentication or elevated privileges.
The technical flaw manifests through improper input validation within the TCP/IP driver's packet processing routines, where the kernel fails to adequately handle malformed or specially crafted TCP segments that contain unexpected sequence numbers or window sizes. This weakness falls under the Common Weakness Enumeration category of weak input validation, specifically CWE-20, which occurs when applications fail to properly validate input data before processing. The vulnerability is particularly concerning because it operates at the kernel level, meaning that successful exploitation can lead to complete system compromise or forced reboots. Attackers can leverage this flaw by sending carefully constructed TCP packets to a target system, causing the TCP/IP driver to enter an inconsistent state that results in system instability and denial of service conditions. The flaw affects multiple Windows versions including Windows 10, Windows Server 2016, and Windows Server 2019, making it a widespread concern across enterprise environments.
The operational impact of CVE-2021-34490 extends beyond simple service disruption to potentially compromise business continuity and network availability. Organizations relying on Windows-based infrastructure face significant risk when this vulnerability is exploited, as network services may become unavailable for extended periods, affecting critical applications and user productivity. The vulnerability's remote exploitability means that attackers can target systems from outside the network perimeter, making it particularly dangerous for organizations with exposed network services or endpoints. In enterprise environments, this flaw can lead to cascading failures where network outages affect multiple systems simultaneously, potentially causing financial losses and operational disruptions. The vulnerability's exploitation typically results in system crashes that require manual intervention to restore normal operation, and in some cases may necessitate system reboots or complete network service restoration procedures.
Mitigation strategies for CVE-2021-34490 should include immediate deployment of Microsoft security patches and updates to address the underlying TCP/IP driver vulnerability. Organizations should prioritize patch management procedures to ensure all affected Windows systems receive the necessary security updates as soon as they become available. Network segmentation and firewall configurations can provide additional protection by limiting exposure to potentially malicious traffic and reducing the attack surface for exploitation attempts. Implementing intrusion detection systems that monitor for suspicious TCP traffic patterns may help identify exploitation attempts before they succeed in causing service disruption. Security teams should also consider disabling unnecessary network services and implementing strict access controls to minimize potential attack vectors. The vulnerability's classification under the MITRE ATT&CK framework includes techniques related to privilege escalation and denial of service, making comprehensive defensive measures essential for protecting against both direct exploitation and potential follow-on attacks that may leverage the compromised systems as launch points for further network infiltration.