CVE-2024-42500: HPE HP-UX NFSv4 DoS Vulnerability

CVE-2024-42500 Overview

HPE has identified a critical denial of service vulnerability in HPE HP-UX System's Network File System (NFSv4) services. This vulnerability allows remote attackers to disrupt NFS services without requiring authentication, potentially causing significant operational impact to enterprise environments relying on HP-UX systems for file sharing infrastructure.

Critical Impact

Remote unauthenticated attackers can cause denial of service conditions affecting NFSv4 services on HP-UX systems, with potential for cross-system impact and integrity compromise.

Affected Products

• HPE HP-UX Systems with NFSv4 services enabled
• HP-UX Network File System (NFS) version 4 components

Discovery Timeline

• 2024-09-09 - CVE CVE-2024-42500 published to NVD
• 2024-09-10 - Last updated in NVD database

Technical Details for CVE-2024-42500

Vulnerability Analysis

This denial of service vulnerability resides in the NFSv4 implementation within HPE HP-UX systems. The vulnerability is network-accessible, meaning attackers can exploit it remotely without needing any prior authentication or user interaction. The attack complexity is low, making exploitation straightforward for attackers with network access to vulnerable NFSv4 services.

The vulnerability carries a changed scope, indicating that exploitation can affect resources beyond the vulnerable component itself—potentially impacting other services or systems that depend on the compromised NFS infrastructure. While confidentiality is not directly impacted, the vulnerability allows for low integrity impact alongside high availability impact, suggesting attackers can both disrupt services and potentially manipulate data flows.

Root Cause

The root cause lies in improper handling of NFSv4 protocol requests within the HP-UX NFS implementation. The specific flaw allows maliciously crafted network requests to trigger conditions that result in service disruption. This represents a resource exhaustion or protocol handling issue that fails to properly validate or limit malicious input.

Attack Vector

The vulnerability is exploited over the network, targeting NFSv4 services on HP-UX systems. An attacker does not require authentication, privileges, or user interaction to successfully exploit this vulnerability. The attack can be initiated remotely from any network location that can reach the target NFSv4 service, typically on NFS standard ports (port 2049 for NFSv4).

The exploitation mechanism involves sending specially crafted NFSv4 protocol messages to the vulnerable service, causing resource exhaustion, service crashes, or other denial of service conditions that render the NFS service unavailable to legitimate users and applications.

Detection Methods for CVE-2024-42500

Indicators of Compromise

• Unexpected NFS service crashes or restarts on HP-UX systems
• Abnormal NFSv4 traffic patterns or malformed protocol requests in network logs
• Service degradation or unavailability of NFS mounts for client systems
• Increased resource consumption (CPU, memory) on systems running NFSv4 services

Detection Strategies

• Monitor HP-UX system logs for NFS service failures, crashes, or unexpected restarts
• Implement network intrusion detection rules to identify anomalous NFSv4 traffic patterns
• Deploy network traffic analysis to detect high volumes of malformed or suspicious NFS requests
• Configure alerting for NFS service availability and response time degradation

Monitoring Recommendations

• Enable comprehensive logging for NFSv4 services on HP-UX systems
• Implement real-time monitoring of NFS service health and availability metrics
• Deploy network segmentation to limit exposure of NFSv4 services to untrusted networks
• Correlate NFS service events with network traffic logs to identify attack patterns

How to Mitigate CVE-2024-42500

Immediate Actions Required

• Review and apply the security patch referenced in the HPE Security Bulletin
• Restrict network access to NFSv4 services using firewall rules to limit exposure
• Implement network segmentation to isolate HP-UX systems running vulnerable NFS services
• Monitor NFSv4 services for signs of exploitation while awaiting patch deployment

Patch Information

HPE has released a security bulletin addressing this vulnerability. Administrators should consult the HPE Security Bulletin (hpesbux04697en_us) for specific patch details, affected versions, and installation instructions. The bulletin provides guidance on obtaining and applying the necessary security updates for HP-UX NFSv4 services.

Workarounds

• Restrict NFSv4 service access to trusted networks and IP addresses only using firewall rules
• Disable NFSv4 services on systems where they are not required for business operations
• Implement network-level access controls to limit which clients can connect to NFS services
• Consider using VPN or other secure access methods for remote NFS access until patching is complete

Firewall configuration should be applied to restrict NFSv4 access. Consult HP-UX documentation and the security bulletin for specific configuration guidance applicable to your environment.