CVE-2012-1311 in IOS XE
Summary
by MITRE
The RSVP feature in Cisco IOS 15.0 and 15.1 and IOS XE 3.2.xS through 3.4.xS before 3.4.2S, when a VRF interface is configured, allows remote attackers to cause a denial of service (interface queue wedge and service outage) via crafted RSVP packets, aka Bug ID CSCts80643.
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Analysis
by VulDB Data Team • 12/23/2024
The vulnerability described in CVE-2012-1311 represents a critical denial of service flaw within Cisco IOS and IOS XE operating systems that specifically affects the Resource Reservation Protocol (RSVP) implementation. This weakness manifests when RSVP is enabled on Virtual Routing and Forwarding (VRF) interfaces, creating a condition where maliciously crafted RSVP packets can trigger system instability. The vulnerability impacts Cisco IOS versions 15.0 and 15.1, as well as IOS XE versions 3.2.xS through 3.4.xS prior to 3.4.2S, making it a widespread issue across multiple product lines. The flaw operates at the network protocol level, specifically targeting the RSVP signaling mechanism that is essential for quality of service implementations in enterprise networks.
The technical implementation of this vulnerability stems from insufficient input validation within the RSVP processing code when handling packets on VRF interfaces. When the system receives crafted RSVP messages, the parsing logic fails to properly handle malformed or unexpected packet structures, leading to an interface queue wedge condition. This condition occurs because the system's internal packet processing queues become corrupted or blocked, preventing legitimate traffic from being processed while the system remains in a partially functional state. The vulnerability specifically leverages the interaction between RSVP and VRF configurations, where the VRF context creates a unique processing path that does not adequately validate RSVP packet contents before attempting to queue them for processing. According to CWE classification, this represents a weakness in input validation (CWE-20) combined with improper handling of exceptional conditions (CWE-396), while the ATT&CK framework would categorize this as a Denial of Service technique utilizing protocol manipulation.
The operational impact of this vulnerability extends beyond simple service interruption, creating cascading effects throughout network infrastructure that can result in complete service outages. When an interface experiences a queue wedge, it effectively becomes non-functional for traffic processing, potentially isolating entire network segments or routing domains. Network administrators may observe symptoms including interface status changes, packet loss, routing instability, and complete service disruption on affected VRF interfaces. The vulnerability's remote exploitation capability means that attackers can trigger the condition from outside the network perimeter without requiring local access or authentication credentials, making it particularly dangerous in production environments. The timing of the attack can be critical as the system may not immediately recover from the queue wedge condition, potentially requiring manual intervention or device reboot to restore normal operations.
Mitigation strategies for CVE-2012-1311 should focus on both immediate protective measures and long-term remediation approaches. The most effective immediate solution involves applying the vendor-supplied software patches that address the RSVP processing logic and input validation issues. Network administrators should also implement access control measures such as filtering RSVP traffic at network boundaries using firewall rules or access control lists to prevent unauthorized packet injection. Additionally, implementing monitoring solutions that can detect abnormal queue behavior or RSVP packet patterns may help identify exploitation attempts before they cause service disruption. Organizations should consider disabling RSVP functionality on VRF interfaces if it is not strictly required for their network operations, though this may impact QoS implementations. The remediation process should include comprehensive testing of patched systems to ensure that the vulnerability is fully resolved without introducing new compatibility issues, particularly in complex network environments where VRF and RSVP configurations are extensively deployed.