CVE-2013-5478 in IOS
Summary
by MITRE
Cisco IOS 15.0 through 15.3 and IOS XE 3.2 through 3.8, when a VRF interface exists, allows remote attackers to cause a denial of service (interface queue wedge) via crafted UDP RSVP packets, aka Bug ID CSCuf17023.
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Analysis
by VulDB Data Team • 12/24/2024
Cisco IOS versions 15.0 through 15.3 and IOS XE versions 3.2 through 3.8 contain a critical vulnerability in the Resource Reservation Protocol implementation that affects VRF (Virtual Routing and Forwarding) interfaces. This vulnerability manifests when the system receives specially crafted UDP RSVP packets that trigger an interface queue wedge condition, effectively causing a denial of service scenario. The flaw specifically impacts devices that have VRF interfaces configured, making it particularly dangerous in enterprise networks where VRFs are commonly deployed for network segmentation and isolation. The vulnerability is catalogued as CSCuf17023 and represents a significant weakness in the routing protocol handling mechanisms of these Cisco IOS versions.
The technical root cause of this vulnerability lies in the improper handling of RSVP packet processing within the VRF context. When the system receives malformed or specially constructed UDP packets designed to exploit the RSVP protocol implementation, the packet processing logic fails to properly validate or handle these inputs. This leads to a condition where interface queues become wedged or blocked, preventing normal packet forwarding operations. The flaw occurs during the packet parsing and queue management phases of the network processing pipeline, where the system does not adequately sanitize incoming RSVP traffic that is destined for VRF interfaces. This processing error creates a race condition or resource exhaustion scenario that results in the interface becoming unresponsive.
The operational impact of this vulnerability extends beyond simple service disruption as it can affect critical network infrastructure components. Network administrators may observe complete loss of connectivity on affected interfaces, requiring manual intervention to restore normal operations through device rebooting or interface reset procedures. The vulnerability affects both IPv4 and IPv6 RSVP implementations, making it particularly concerning for modern networks that utilize both protocol versions. In enterprise environments where VRFs are extensively used for customer separation, multi-tenant networks, or security segmentation, this vulnerability can result in widespread service outages that impact multiple network domains simultaneously. The remote nature of the attack means that adversaries can exploit this vulnerability from outside the network perimeter without requiring authentication or physical access to the affected devices.
Organizations should implement immediate mitigations including applying the relevant Cisco security advisories and patches that address the RSVP packet handling logic. Network segmentation strategies can help limit the scope of potential exploitation by isolating VRF interfaces from untrusted network segments where malicious traffic might originate. Implementing ingress filtering and access control lists that restrict RSVP traffic to trusted sources can provide additional protection layers. Monitoring network traffic for unusual RSVP packet patterns and implementing intrusion detection systems can help detect exploitation attempts before they cause service disruption. The vulnerability aligns with CWE-129, which addresses improper validation of input boundaries, and maps to ATT&CK technique T1498, which covers network denial of service attacks. Organizations should also consider implementing redundant network paths and automated failover mechanisms to minimize the impact of potential exploitation attempts.