CVE-2011-2058 in IOS
Summary
by MITRE
The cat6000-dot1x component in Cisco IOS 12.2 before 12.2(33)SXI7 does not properly handle an external loop between a pair of dot1x enabled ports, which allows remote attackers to cause a denial of service (traffic storm) via unspecified vectors that trigger many unicast EAPoL Protocol Data Units (PDUs), aka Bug ID CSCtq36336.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 11/24/2021
The vulnerability identified as CVE-2011-2058 resides within the cat6000-dot1x component of Cisco IOS software version 12.2 prior to 12.2(33)SXI7, representing a critical flaw in network authentication mechanisms that can lead to significant service disruption. This issue specifically affects Cisco Catalyst 6000 series switches and manifests when an external loop occurs between two ports that have IEEE 802.1X authentication enabled. The vulnerability stems from improper handling of EAPoL (Extensible Authentication Protocol over Local Area Network) Protocol Data Units, which are fundamental components of the 802.1X authentication framework that govern network access control. The flaw operates under CWE-121, which categorizes memory handling issues, and more specifically aligns with CWE-129, concerning the improper handling of buffer boundaries, as the system fails to properly manage the flow of authentication PDUs in looped network conditions. The vulnerability operates within the ATT&CK framework under the T1499.004 technique, specifically targeting network denial of service through traffic storms, which represents a sophisticated method of compromising network availability.
The technical implementation of this vulnerability involves the creation of a traffic storm scenario when two 802.1X enabled ports form an external loop within the network infrastructure. When such a loop occurs, the system enters a state where EAPoL PDUs are continuously transmitted between the ports, creating an exponential increase in network traffic that can overwhelm the switch's processing capabilities. The mechanism by which this occurs involves the authentication process failing to detect and break the loop condition, causing the system to repeatedly process authentication requests and responses. This results in an uncontrolled proliferation of EAPoL PDUs, which are typically used for authentication negotiation but become weaponized in this scenario to generate massive amounts of network traffic. The vulnerability specifically exploits the lack of loop detection mechanisms within the dot1x component, where the system does not implement proper monitoring of port states or authentication session loops that would normally prevent such conditions from occurring.
The operational impact of CVE-2011-2058 extends beyond simple network disruption to potentially compromise the entire network infrastructure's availability and reliability. When a traffic storm occurs, it can cause the affected switch to become unresponsive or crash entirely, leading to complete loss of network connectivity for all devices connected to that switch. The severity of the impact is amplified by the fact that the vulnerability can be triggered remotely without requiring authentication, making it particularly dangerous as any attacker with network access can exploit this condition. Network administrators may experience extended downtime while attempting to diagnose and resolve the issue, as the traffic storm can consume significant bandwidth and processing resources. The vulnerability essentially creates a condition where the network authentication system becomes a vector for its own destruction, turning the security mechanism designed to protect the network into a tool for network disruption.
Mitigation strategies for CVE-2011-2058 must address both immediate remediation and long-term network architecture improvements to prevent similar conditions from occurring. The primary and most effective mitigation involves upgrading the affected Cisco IOS software to version 12.2(33)SXI7 or later, which includes patches that properly handle the loop detection and EAPoL PDU processing. Network administrators should also implement proper network segmentation and avoid creating physical loops in the network topology, particularly in areas where 802.1X authentication is enabled. Additionally, implementing port security measures and enabling Spanning Tree Protocol can help prevent the conditions that lead to the vulnerability being exploited. Organizations should also consider implementing network monitoring tools that can detect unusual traffic patterns and alert administrators to potential traffic storm conditions. The mitigation approach should align with the NIST Cybersecurity Framework's protective measures, focusing on ensuring system resilience and implementing continuous monitoring to detect anomalous behavior in network authentication processes. Regular network assessments should be conducted to identify potential loop conditions and ensure that all network devices are running patched firmware versions that address known vulnerabilities in authentication mechanisms.