CVE-2003-1002 in Catalyst 6500
Summary
by MITRE
Cisco Firewall Services Module (FWSM) in Cisco Catalyst 6500 and 7600 series devices allows remote attackers to cause a denial of service (crash and reload) via an SNMPv3 message when snmp-server is set.
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Analysis
by VulDB Data Team • 06/27/2019
The vulnerability identified as CVE-2003-1002 represents a critical denial of service flaw within Cisco's Firewall Services Module FWSM implementation. This security weakness specifically affects Cisco Catalyst 6500 and 7600 series network devices that have SNMPv3 configured through the snmp-server command. The flaw manifests when the FWSM processes certain malformed or specially crafted SNMPv3 messages, leading to system instability and complete device reboot cycles. This vulnerability demonstrates a fundamental issue in how the FWSM handles SNMP protocol processing, particularly in the context of SNMP version 3 authentication and encryption mechanisms.
The technical root cause of this vulnerability stems from insufficient input validation within the SNMPv3 processing subsystem of the FWSM module. When an SNMPv3 message is received and processed by the device, the system fails to properly validate the message structure and authentication parameters before attempting to parse and process the data. This lack of proper validation creates a condition where specially crafted malicious SNMPv3 packets can trigger buffer overflows or other memory corruption issues within the FWSM's SNMP processing engine. The vulnerability is classified under CWE-121 as a buffer overflow condition, specifically occurring in the context of network protocol handling where insufficient bounds checking allows attackers to manipulate system memory.
From an operational perspective, this vulnerability presents significant risk to network infrastructure availability and reliability. Network administrators responsible for maintaining Cisco Catalyst 6500 and 7600 series devices with SNMPv3 enabled face potential service disruption from remote attackers who can exploit this flaw to force device reboots. The impact extends beyond simple service interruption as the repeated reload cycles can cause extended network downtime, potentially affecting critical network services and communications. The vulnerability is particularly concerning because it requires no authentication to exploit, making it accessible to any remote attacker who can send SNMPv3 packets to the affected device, which aligns with ATT&CK technique T1499.002 for network disruption through service availability.
The exploitation of this vulnerability follows a straightforward methodology where attackers send carefully constructed SNMPv3 messages to the target device's SNMP port, typically UDP port 161. The attack can be executed from any network location where the attacker has network connectivity to the device, making it particularly dangerous in environments where SNMP is exposed to untrusted networks. The device will process the malformed message and subsequently crash, requiring manual intervention or automatic reload to restore service. This vulnerability demonstrates the importance of proper protocol implementation and input validation in network security devices, as the flaw exists in the fundamental processing of network management protocols rather than in application-specific functionality.
Organizations affected by this vulnerability should implement immediate mitigations including disabling SNMPv3 on affected devices when possible, implementing network segmentation to restrict SNMP access, or applying Cisco's official security patches. The vulnerability highlights the need for comprehensive network security testing and the importance of validating network management protocol implementations against known attack patterns. Network administrators should also consider implementing intrusion detection systems to monitor for unusual SNMP traffic patterns that might indicate exploitation attempts. This vulnerability serves as a reminder of the critical importance of maintaining current security patches and implementing defense-in-depth strategies that protect against both known and emerging threats in network infrastructure components.