CVE-2012-3915 in IOS
Summary
by MITRE
The DMVPN tunnel implementation in Cisco IOS 15.2 allows remote attackers to cause a denial of service (persistent IKE state) via a large volume of hub-to-spoke traffic, aka Bug ID CSCtq39602.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 04/17/2017
The vulnerability described in CVE-2012-3915 represents a significant denial of service weakness within Cisco IOS 15.2 implementations, specifically affecting Dynamic Multipoint Virtual Private Network (DMVPN) tunnel configurations. This flaw manifests through the improper handling of IKE (Internet Key Exchange) state management when processing high volumes of hub-to-spoke traffic patterns, creating a persistent state condition that ultimately leads to service disruption. The vulnerability impacts organizations relying on DMVPN for secure network connectivity between central hubs and remote spokes, potentially affecting critical business operations and network availability.
The technical root cause of this vulnerability stems from insufficient state management within the IKE protocol implementation in Cisco IOS 15.2. When the system receives an excessive volume of traffic from hub to spoke nodes, the IKE state machine fails to properly handle the incoming packets, leading to accumulation of stale or malformed IKE states that persist indefinitely. This condition occurs because the implementation lacks adequate rate limiting and state cleanup mechanisms for handling high-frequency traffic patterns typical in DMVPN environments. The flaw specifically affects the IKEv1 protocol implementation within the DMVPN framework, where the state management logic does not adequately account for scenarios involving large volumes of concurrent traffic flows.
The operational impact of this vulnerability extends beyond simple service disruption to encompass broader network reliability concerns for organizations utilizing Cisco IOS 15.2 for DMVPN deployments. Attackers can exploit this weakness by generating sustained traffic patterns that overwhelm the IKE state handling capabilities, resulting in persistent denial of service conditions that may require system reboot to resolve. Network administrators face the challenge of maintaining availability for critical remote access and branch office connectivity while dealing with a vulnerability that can be triggered through legitimate traffic patterns, making detection and mitigation particularly challenging in production environments.
Organizations should implement immediate mitigations including applying Cisco's recommended security patches and updates to address the IKE state handling deficiency in IOS 15.2. Network segmentation and traffic filtering measures can help reduce the attack surface by limiting the volume of hub-to-spoke traffic that reaches vulnerable systems. Additionally, implementing monitoring solutions to detect unusual IKE state accumulation patterns can provide early warning of potential exploitation attempts. The vulnerability aligns with CWE-400, which addresses improper handling of resource exhaustion conditions, and relates to ATT&CK technique T1499.004 for network disruption through resource exhaustion attacks. Organizations should also consider implementing rate limiting mechanisms at network boundaries and configuring appropriate logging to track IKE state changes for security monitoring purposes.