CVE-2015-0015 in Windows
Summary
by MITRE
Microsoft Windows Server 2003 SP2, Server 2008 SP2 and R2 SP1, and Server 2012 Gold and R2 allow remote attackers to cause a denial of service (system hang and RADIUS outage) via crafted username strings to (1) Internet Authentication Service (IAS) or (2) Network Policy Server (NPS), aka "Network Policy Server RADIUS Implementation Denial of Service Vulnerability."
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Analysis
by VulDB Data Team • 03/02/2022
This vulnerability resides in the Network Policy Server RADIUS implementation within Microsoft Windows Server operating systems including Windows Server 2003 SP2, Server 2008 SP2 and R2 SP1, and Server 2012 Gold and R2. The flaw manifests when the system receives crafted username strings through the Internet Authentication Service (IAS) or Network Policy Server (NPS) components, leading to system hangs and complete RADIUS service outages. The vulnerability represents a classic denial of service condition that can severely impact network infrastructure by disrupting authentication services critical to enterprise security operations.
The technical mechanism behind this vulnerability involves improper input validation within the RADIUS protocol implementation. When malformed or specially crafted username strings are processed by the NPS or IAS services, the system fails to properly handle these inputs, resulting in a state where the service becomes unresponsive or crashes entirely. This behavior stems from insufficient bounds checking and error handling in the username parsing logic, allowing malicious actors to exploit the protocol implementation directly through network-based attacks without requiring authentication. The vulnerability is categorized under CWE-129 as an insufficient input validation issue, specifically manifesting as an improper input validation weakness in the RADIUS authentication service.
The operational impact of this vulnerability extends beyond simple service disruption to encompass broader network security implications. Organizations relying on Windows Server for network access control and authentication services face significant risk of unauthorized network access when the RADIUS service becomes unavailable. The system hang condition can persist for extended periods, potentially leading to cascading failures in network authentication, VPN access, wireless network connectivity, and other services dependent on RADIUS authentication. Security teams may experience challenges in monitoring and incident response as the affected services become unresponsive, potentially masking other security events during the outage period. This vulnerability directly affects the availability aspect of the CIA triad, compromising the network infrastructure's ability to provide authentication services essential for maintaining secure network access controls.
Mitigation strategies for this vulnerability should prioritize immediate patch deployment through Microsoft security updates, specifically addressing the RADIUS implementation flaws in affected server versions. Organizations must implement network segmentation and access controls to limit exposure of vulnerable systems to untrusted networks. Monitoring should be enhanced to detect unusual authentication patterns or service disruptions that may indicate exploitation attempts. Network administrators should consider implementing redundant authentication services and failover mechanisms to maintain network access during potential outages. The vulnerability demonstrates the importance of maintaining up-to-date security patches and implementing defense-in-depth strategies as outlined in the MITRE ATT&CK framework's privilege escalation and defense evasion techniques. Additionally, organizations should conduct regular security assessments of their authentication infrastructure and establish incident response procedures specifically addressing RADIUS service disruptions to minimize business impact during exploitation attempts.