CVE-2011-1871 in Windows
Summary
by MITRE
Tcpip.sys in the TCP/IP stack in Microsoft Windows Vista SP2, Windows Server 2008 SP2, R2, and R2 SP1, and Windows 7 Gold and SP1 allows remote attackers to cause a denial of service (reboot) via a series of crafted ICMP messages, aka "ICMP Denial of Service Vulnerability."
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Analysis
by VulDB Data Team • 03/19/2021
The vulnerability identified as CVE-2011-1871 represents a critical flaw in the Windows TCP/IP stack implementation that affects multiple operating system versions including Windows Vista SP2, Windows Server 2008 SP2 and R2, and Windows 7 Gold and SP1. This vulnerability specifically resides within the Tcpip.sys driver component which serves as the core networking driver responsible for handling internet control message protocol traffic. The flaw manifests when the system processes a sequence of specially crafted ICMP messages that exploit an insufficient input validation mechanism in the network stack's handling of these protocol packets.
The technical nature of this vulnerability stems from improper validation of ICMP message parameters within the kernel-level Tcpip.sys driver. When the system receives malformed or specially constructed ICMP packets, the driver fails to properly validate the message structure and content before processing them, leading to a buffer overflow condition or other memory corruption issues. This weakness allows remote attackers to craft specific sequences of ICMP messages that, when processed by the vulnerable Windows systems, trigger an unexpected system state that results in an immediate system reboot. The vulnerability operates at the kernel level, making it particularly dangerous as it can be exploited without requiring local system access or elevated privileges.
From an operational impact perspective, this vulnerability presents a significant risk to network availability and system stability across affected Windows deployments. The remote exploitation capability means that attackers can initiate denial of service attacks from anywhere on the network without needing physical access or authentication credentials. The resulting system reboots can disrupt critical services, cause data loss, and potentially provide attackers with opportunities to establish persistent access points. Organizations running affected systems face potential business disruption, especially in environments where continuous availability is critical such as financial services, healthcare systems, or industrial control networks. The vulnerability's exploitation does not require any special privileges or authentication, making it particularly attractive to attackers seeking to disrupt services on target networks.
The mitigation strategies for this vulnerability primarily focus on applying the official Microsoft security patches released as part of the vulnerability remediation process. Organizations should prioritize immediate deployment of the relevant security updates, particularly the Windows Update patches that address the Tcpip.sys driver vulnerability. Network administrators can also implement temporary network-level mitigations such as filtering ICMP traffic at perimeter firewalls or implementing ingress/egress filtering rules to prevent malformed ICMP packets from reaching vulnerable systems. Additionally, implementing intrusion detection systems that can identify suspicious ICMP traffic patterns may provide early warning of exploitation attempts. The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and represents a classic example of a remote code execution vulnerability that can be leveraged for denial of service attacks. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and defense evasion, though the primary impact remains focused on service disruption rather than lateral movement or data compromise. Organizations should also conduct comprehensive vulnerability assessments to identify all systems running affected Windows versions and ensure proper patch management processes are in place to prevent future similar incidents.