CVE-2002-0318 in FreeRADIUS
Summary
by MITRE
FreeRADIUS RADIUS server allows remote attackers to cause a denial of service (CPU consumption) via a flood of Access-Request packets.
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Analysis
by VulDB Data Team • 10/23/2024
The vulnerability identified as CVE-2002-0318 affects the FreeRADIUS RADIUS server implementation, representing a significant security concern that enables remote attackers to execute denial of service attacks through excessive CPU resource consumption. This issue manifests when the server receives a flood of Access-Request packets, causing the system to become overwhelmed and consume excessive processing power. The vulnerability falls under the category of resource exhaustion attacks, where malicious actors exploit the server's processing capabilities to disrupt legitimate service availability. The FreeRADIUS server, which operates as a RADIUS authentication server implementing the Remote Authentication Dial In User Service protocol, becomes vulnerable due to its inability to effectively rate limit or process high volumes of authentication requests. This flaw represents a critical weakness in the server's defensive mechanisms against traffic flooding attacks, particularly targeting the authentication processing pipeline where each Access-Request packet triggers a series of validation steps that consume substantial CPU cycles.
The technical implementation of this vulnerability stems from the server's insufficient handling of concurrent authentication requests without proper rate limiting or connection management controls. When an attacker floods the server with multiple Access-Request packets simultaneously, the FreeRADIUS daemon begins processing each request individually, executing authentication validation routines that include user credential verification, attribute checking, and access control evaluation. Each processed packet consumes CPU resources proportional to the complexity of the authentication checks, and without proper throttling mechanisms, the server's processing capacity becomes saturated. The vulnerability specifically exploits the server's lack of protection against request flooding, where the processing of legitimate requests becomes overwhelmed by malicious traffic, leading to a degradation of service performance or complete system unresponsiveness. This behavior aligns with CWE-400, which categorizes resource exhaustion vulnerabilities as those that allow attackers to consume system resources beyond normal operational limits. The flaw demonstrates poor input validation and rate limiting implementation within the server's network processing layer, where the absence of traffic shaping or connection limiting protocols enables attackers to exploit the server's processing capabilities for malicious purposes.
The operational impact of CVE-2002-0318 extends beyond simple service disruption to potentially compromise the entire network authentication infrastructure. Organizations relying on FreeRADIUS for network access control, wireless authentication, or VPN access may experience complete service outages when this vulnerability is exploited, affecting thousands of users who depend on the authentication system for network connectivity. The vulnerability particularly impacts environments where RADIUS servers handle high volumes of authentication requests such as enterprise networks, educational institutions, or public wireless access points. The CPU consumption patterns associated with this attack can cause cascading effects throughout the network infrastructure, as the server becomes unresponsive to legitimate authentication requests and potentially impacts other network services that depend on the availability of the authentication system. From an operational security perspective, this vulnerability enables attackers to perform low-cost, high-impact denial of service attacks that require minimal technical expertise while causing significant disruption to network operations and user productivity. The attack vector represents a classic example of a layer 7 denial of service attack that targets application-level processing rather than network-level bandwidth exhaustion.
Mitigation strategies for CVE-2002-0318 should focus on implementing robust rate limiting, connection management, and traffic monitoring mechanisms to prevent the exploitation of the vulnerability. Network administrators should deploy firewall rules and access control lists to limit the rate of incoming Access-Request packets from individual sources, effectively implementing traffic shaping to prevent flooding attacks. The implementation of proper rate limiting at the network perimeter using tools such as iptables or dedicated network security appliances can significantly reduce the impact of such attacks by enforcing maximum connection rates and request frequencies. Additionally, configuring the FreeRADIUS server with appropriate timeouts, connection limits, and authentication request processing thresholds can help prevent the server from becoming overwhelmed. Organizations should also consider implementing intrusion detection systems that can identify and alert on unusual traffic patterns indicative of flooding attacks, providing early warning of potential exploitation attempts. The implementation of these controls aligns with ATT&CK technique T1498, which describes the use of resource exhaustion attacks to deny service to legitimate users. Regular security updates and patches to the FreeRADIUS server implementation are essential to address the underlying vulnerability, while network monitoring and logging should be enhanced to detect anomalous authentication request patterns that could indicate exploitation attempts. The deployment of redundant authentication systems and proper network segmentation can further reduce the impact of successful attacks by isolating vulnerable components and maintaining service availability during attack scenarios.