CVE-2001-0741 in HSRP
Summary
by MITRE
Cisco Hot Standby Routing Protocol (HSRP) allows local attackers to cause a denial of service by spoofing HSRP packets.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 08/24/2024
The Cisco Hot Standby Routing Protocol HSRP vulnerability identified as CVE-2001-0741 represents a critical security flaw in the implementation of the HSRP protocol that governs high availability network configurations. This vulnerability specifically targets the authentication mechanisms within HSRP, which is designed to provide transparent failover capabilities for network gateways. The protocol operates by allowing multiple routers to form a group where one acts as the active router while others remain in standby mode, automatically taking over in case of failure. The flaw arises from insufficient validation of HSRP packet authenticity, creating an avenue for malicious actors to exploit the system.
The technical implementation of this vulnerability stems from the weak authentication model employed by HSRP version 1, which relies on a simple password mechanism that can be easily discovered or brute-forced. Attackers with local network access can craft and transmit spoofed HSRP packets that appear to originate from legitimate standby routers within the group. This spoofing capability allows adversaries to manipulate the active router selection process, effectively causing network disruption by forcing unnecessary failovers or by assuming control of the active router role. The vulnerability is classified under CWE-287 which addresses improper authentication issues, specifically focusing on weak or predictable authentication mechanisms that can be exploited by unauthorized users.
The operational impact of this vulnerability extends beyond simple network disruption to encompass potential complete service outages and unauthorized network control. When exploited successfully, attackers can cause repeated failover events that degrade network performance and reliability, leading to extended periods of service unavailability. The denial of service condition affects not only the immediate network segment but can cascade through interconnected systems, particularly in enterprise environments where HSRP is widely deployed for critical infrastructure protection. Network administrators may experience difficulty in troubleshooting these issues since the malicious activity appears to originate from legitimate network devices, complicating detection and response efforts. This vulnerability directly aligns with ATT&CK technique T1499.004 which describes network denial of service attacks targeting network infrastructure components.
Mitigation strategies for CVE-2001-0741 require immediate implementation of enhanced authentication mechanisms and network monitoring protocols. Organizations should upgrade to HSRP version 2 or later implementations that provide stronger authentication methods and cryptographic protection for HSRP packets. Network segmentation and access control measures should be implemented to limit local network access to only authorized personnel, reducing the attack surface available to potential adversaries. Regular network monitoring should be deployed to detect unusual HSRP packet patterns and unauthorized router role changes. Additionally, implementing network intrusion detection systems capable of identifying spoofed HSRP traffic can provide early warning of exploitation attempts. The most effective long-term solution involves migrating to more secure protocols such as VRRP version 3 or implementing proper network access controls and authentication frameworks that align with industry standards for network infrastructure security.