CVE-2023-24901 in Windows
Summary
by MITRE • 05/09/2023
Windows NFS Portmapper Information Disclosure Vulnerability
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Analysis
by VulDB Data Team • 06/01/2023
The Windows NFS Portmapper Information Disclosure Vulnerability represents a critical security flaw in the Network File System implementation that affects Windows operating systems. This vulnerability specifically impacts the NFS portmapper service which is responsible for mapping NFS program numbers to network ports, enabling clients to locate NFS services on remote servers. The issue arises from improper handling of certain RPC (Remote Procedure Call) requests that allow unauthorized access to internal port mapping information, potentially exposing sensitive details about network services and their configurations. This vulnerability exists within the core Windows networking stack and affects systems running various Windows versions including Windows 10, Windows 11, and Windows Server editions. The flaw stems from insufficient validation of incoming RPC requests, particularly those targeting the portmapper service that operates on TCP and UDP port 111, making it a prime target for reconnaissance activities by malicious actors.
The technical exploitation of this vulnerability occurs when an attacker sends specially crafted RPC requests to the NFS portmapper service without proper authentication or authorization checks. The portmapper service, designed to facilitate NFS service discovery, inadvertently reveals information about registered services and their corresponding ports when processing malformed or unauthorized requests. This information disclosure includes details about the NFS server configuration, service availability, and potentially other network services running on the same system. The vulnerability is classified as a information disclosure issue under the Common Weakness Enumeration framework with CWE-200, which specifically addresses the exposure of sensitive information to unauthorized actors. The flaw allows attackers to gather intelligence about the target network infrastructure, potentially enabling more sophisticated attacks such as service enumeration, vulnerability assessment, and targeted exploitation of other network services. The impact is amplified because NFS portmapper information can reveal not only NFS services but also other services that might be running on the same ports, providing attackers with comprehensive mapping of the target network.
From an operational perspective, this vulnerability creates significant risks for organizations relying on Windows NFS implementations, particularly in enterprise environments where network service discovery and mapping are critical for system administration. The information disclosure can enable attackers to identify potential attack vectors, understand service configurations, and plan more effective exploitation strategies. The vulnerability is particularly concerning in environments where Windows NFS servers are exposed to untrusted networks or where the portmapper service is running on systems that are not properly secured. Organizations may experience cascading effects from this vulnerability as the leaked information can be used to identify additional targets within the network, potentially leading to lateral movement and privilege escalation. The attack surface is broadened because the portmapper service operates at a fundamental level of the networking stack, making it difficult to isolate and secure without comprehensive network monitoring and access controls. This vulnerability aligns with ATT&CK technique T1046 which focuses on network service scanning and reconnaissance activities, making it a valuable intelligence-gathering tool for adversaries.
Effective mitigation strategies for this vulnerability require immediate patching of affected Windows systems through Microsoft security updates, which address the improper validation of RPC requests in the NFS portmapper service. Organizations should implement network segmentation to limit access to NFS services and restrict communication on ports 111/tcp and 111/udp to trusted networks only. The deployment of network monitoring tools and intrusion detection systems can help identify suspicious RPC traffic patterns that may indicate exploitation attempts. Additionally, disabling NFS services on systems where they are not required provides an additional layer of defense. System administrators should conduct comprehensive network audits to identify all systems running NFS services and ensure that proper access controls are implemented. The vulnerability highlights the importance of implementing least privilege principles for network services and maintaining current security patches across all system components. Organizations should also consider implementing network access control lists to restrict RPC traffic and ensure that only authorized systems can communicate with the NFS portmapper service. Regular security assessments and vulnerability scanning should be conducted to identify and remediate similar issues in the broader network infrastructure.