CVE-2014-3273 in IOS
Summary
by MITRE
The LLDP implementation in Cisco IOS allows remote attackers to cause a denial of service (device reload) via a malformed packet, aka Bug ID CSCum96282.
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Analysis
by VulDB Data Team • 12/17/2024
The vulnerability described in CVE-2014-3273 represents a critical flaw in Cisco IOS operating systems that affects the Link Layer Discovery Protocol implementation. This issue specifically targets the LLDP functionality which is used by network devices to advertise their identity, configuration, and capabilities to neighboring devices on a local network segment. The vulnerability stems from insufficient input validation within the LLDP packet processing mechanism, allowing malicious actors to craft specially crafted packets that trigger unexpected behavior in the affected Cisco devices. When such malformed packets are received by an affected device, the system experiences a complete reload or reboot, effectively causing a denial of service condition that disrupts network operations.
The technical root cause of this vulnerability lies in the improper handling of malformed LLDP packets during the parsing and processing stages of the protocol implementation. According to CWE classification, this represents a weakness in input validation where the system fails to properly validate the structure and content of received network packets before processing them. The flaw manifests when the Cisco IOS device attempts to parse the malformed LLDP packet and encounters unexpected data structures or invalid field values that cause the device's memory management or processing routines to fail catastrophically. This type of vulnerability falls under the ATT&CK technique T1499.004 which describes network denial of service attacks targeting network infrastructure devices. The attack vector is particularly dangerous because it requires no authentication or privileged access, making it a significant threat that can be exploited by anyone with network access to the affected device.
The operational impact of this vulnerability extends far beyond simple service disruption as it can lead to cascading failures across network infrastructure. When an affected Cisco device experiences a reload due to the malformed LLDP packet, it creates a temporary loss of network connectivity for all devices connected to that segment. Network administrators may experience difficulty in maintaining network stability, particularly in environments where multiple devices are interconnected through LLDP-enabled switches and routers. The vulnerability affects a wide range of Cisco IOS devices including various models of switches, routers, and other network infrastructure equipment that support LLDP functionality. The attack can be particularly devastating in mission-critical environments where network availability is paramount, as the device reload can take several minutes to complete, resulting in extended periods of network downtime.
Mitigation strategies for this vulnerability require immediate attention from network administrators and should include implementing network segmentation to limit the scope of potential attacks, deploying packet filtering rules at network boundaries to block malformed LLDP traffic, and applying the appropriate Cisco IOS software patches released to address the specific vulnerability. The recommended approach involves upgrading affected devices to Cisco IOS versions that contain the necessary security fixes and implementing proper network monitoring to detect unusual LLDP packet patterns that might indicate exploitation attempts. Organizations should also consider disabling LLDP functionality on devices where it is not strictly required, particularly in border network segments where external network access is possible. Additionally, network administrators should establish incident response procedures that include rapid identification and isolation of affected devices, along with automated alerting mechanisms to detect potential exploitation attempts. The vulnerability underscores the importance of maintaining up-to-date network device firmware and implementing comprehensive network security monitoring solutions that can detect and respond to protocol-based attacks.