CVE-2021-28439 in Windows
Summary
by MITRE • 04/14/2021
Windows TCP/IP Driver Denial of Service Vulnerability This CVE ID is unique from CVE-2021-28319.
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Analysis
by VulDB Data Team • 04/16/2021
The Windows TCP/IP driver vulnerability identified as CVE-2021-28439 represents a critical denial of service flaw within the Windows operating system's network stack. This vulnerability specifically affects the Transmission Control Protocol/Internet Protocol implementation in Windows systems, potentially allowing remote attackers to disrupt network services and system availability. The flaw exists in the kernel-mode driver components responsible for handling TCP/IP network communications, making it particularly dangerous as it operates at the core of Windows networking functionality.
The technical exploitation of this vulnerability occurs through malformed network packets that trigger improper handling within the TCP/IP driver. When the vulnerable system receives specially crafted TCP segments, the driver fails to properly validate incoming packet structures, leading to system instability and potential crashes. This flaw falls under CWE-121, which describes stack-based buffer overflow conditions, though the specific implementation in this case involves improper input validation within kernel network drivers. The vulnerability demonstrates characteristics consistent with memory corruption issues that can be leveraged to cause system-wide denial of service conditions.
From an operational perspective, successful exploitation of CVE-2021-28439 can result in complete network service disruption for affected Windows systems. Network administrators may observe sudden system crashes, restarts, or complete loss of network connectivity on vulnerable machines. The impact extends beyond individual systems as network infrastructure components that rely on Windows TCP/IP functionality may experience cascading failures. This vulnerability particularly affects servers and network devices running Windows Server operating systems, though client versions may also be impacted depending on their network configuration and usage patterns.
The attack surface for this vulnerability encompasses any Windows system that processes incoming TCP network traffic, including web servers, database servers, file servers, and network appliances. Attackers can leverage this flaw through remote network connections without requiring authentication or elevated privileges. The vulnerability aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and demonstrates how kernel-level flaws can be exploited to achieve system-wide disruption. Organizations with extensive Windows network infrastructures face significant risk exposure, particularly those operating legacy systems or with delayed patch management processes.
Mitigation strategies for CVE-2021-28439 primarily involve applying Microsoft's security patches released through the regular update cycle. System administrators should prioritize deployment of the relevant Windows updates as soon as possible, particularly for critical network infrastructure components. Network segmentation and firewall rules can provide temporary protection by limiting exposure to potentially malicious traffic, though these measures do not address the underlying vulnerability. Monitoring network traffic for unusual patterns or malformed packets may help detect exploitation attempts, though this approach provides reactive rather than preventive protection. Organizations should also consider implementing redundant network services and backup systems to minimize impact from potential exploitation events. The vulnerability underscores the importance of maintaining current security patches and demonstrates how kernel-level network stack flaws can create widespread availability issues across enterprise environments.