CVE-2001-0566 in Catalyst 2900XL Switch
Summary
by MITRE
Cisco Catalyst 2900XL switch allows a remote attacker to create a denial of service via an empty UDP packet sent to port 161 (SNMP) when SNMP is disabled.
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Analysis
by VulDB Data Team • 08/21/2024
The vulnerability identified as CVE-2001-0566 represents a significant denial of service weakness in Cisco Catalyst 2900XL network switches that persisted through a critical flaw in the switch's SNMP processing mechanism. This vulnerability specifically affects devices where SNMP functionality is disabled but the switch continues to process incoming packets on the standard SNMP port 161. The flaw demonstrates how network infrastructure devices can exhibit unexpected behavior when handling malformed or empty packets, creating a potential attack vector that adversaries can exploit to disrupt network operations. The vulnerability's classification under CWE-121 indicates a buffer overflow condition that occurs when the device attempts to process empty UDP packets, highlighting the importance of proper input validation in network protocol implementations.
The technical exploitation of this vulnerability occurs when a remote attacker sends an empty UDP packet to port 161 on a Cisco Catalyst 2900XL switch that has SNMP disabled. The switch's processing logic fails to properly validate the incoming packet structure, causing the device to enter a state where it cannot properly handle subsequent network traffic. This behavior stems from the device's insufficient validation of UDP packet contents, particularly when the packet payload is empty or malformed. The vulnerability operates at the network protocol level and demonstrates how network devices can be rendered non-functional through carefully crafted packet delivery without requiring authentication or privileged access. The attack vector operates entirely over the network without any local access requirements, making it particularly concerning for network administrators who must protect against remote threats.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise network availability and business continuity for organizations relying on Cisco Catalyst 2900XL switches. When exploited successfully, the denial of service condition can render the switch non-functional for extended periods, requiring manual intervention to restore normal operations. Network administrators may experience complete loss of network connectivity through the affected switch, potentially causing cascading failures throughout the network infrastructure. The vulnerability's impact is particularly severe in enterprise environments where these switches serve as core network components, as the disruption can affect multiple network segments and services. The lack of authentication requirements for exploitation means that any remote attacker with network access can potentially trigger this condition, making it a significant threat to network availability.
Mitigation strategies for CVE-2001-0566 should focus on implementing network segmentation and access control measures to prevent unauthorized access to network infrastructure devices. Organizations should consider disabling SNMP entirely on switches where it is not required, as this removes the attack surface entirely. Network administrators should implement firewall rules to block UDP traffic to port 161 on switches that do not require SNMP functionality. The implementation of intrusion detection systems can help identify and alert on suspicious UDP packet patterns that may indicate exploitation attempts. Cisco recommends applying firmware updates that address this specific vulnerability, as the company released patches to fix the buffer overflow condition in subsequent software releases. Additionally, network monitoring should be enhanced to detect unusual patterns in switch behavior that may indicate successful exploitation, as this vulnerability operates at the protocol processing level and may not generate obvious error messages in standard logging systems. The ATT&CK framework categorizes this as a network denial of service attack that leverages protocol implementation weaknesses, making it particularly relevant for organizations implementing comprehensive cybersecurity frameworks.