CVE-2013-5477 in IOS
Summary
by MITRE
The T1/E1 driver-queue functionality in Cisco IOS 12.2 and 15.0 through 15.3, when an HDLC32 driver is used, allows remote attackers to cause a denial of service (interface queue wedge) via bursty network traffic, aka Bug ID CSCub67465.
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Analysis
by VulDB Data Team • 12/24/2024
The vulnerability described in CVE-2013-5477 represents a critical denial of service flaw affecting Cisco IOS implementations across multiple version ranges. This issue specifically targets the T1/E1 driver-queue functionality within Cisco routers and switches that utilize HDLC32 driver configurations. The vulnerability manifests when the system encounters bursty network traffic patterns, causing interface queue wedging that effectively renders the affected communication interfaces unusable. The flaw impacts devices running Cisco IOS version 12.2 and versions 15.0 through 15.3, making it a widespread concern across numerous network infrastructure deployments that rely on T1/E1 interfaces for high-speed data transmission.
The technical mechanism behind this vulnerability involves the interaction between the HDLC32 driver and the T1/E1 interface queue management system within Cisco IOS. When bursty network traffic is transmitted through interfaces configured with HDLC32 driver functionality, the queue processing logic fails to properly handle the sudden influx of data packets. This results in a condition where the interface queue becomes permanently wedged, unable to process additional traffic even after the bursty pattern has ceased. The queue wedge condition prevents normal interface operation and effectively creates a denial of service scenario that can persist until the device is manually rebooted or the affected interface is manually reset. This behavior aligns with CWE-400 vulnerability classification related to resource exhaustion and improper handling of exceptional conditions.
The operational impact of CVE-2013-5477 extends beyond simple service disruption to potentially compromise entire network segments that depend on affected T1/E1 interfaces. Network administrators may experience unexpected outages in critical communication paths, particularly in environments where T1/E1 connections serve as primary or backup links for enterprise communications, MPLS networks, or carrier-grade infrastructure. The remote nature of the attack means that malicious actors can trigger the vulnerability from external network positions without requiring physical access or local credentials, making it particularly dangerous in publicly accessible network environments. This vulnerability directly impacts the availability and reliability of network services, potentially causing cascading failures throughout connected network infrastructure.
Mitigation strategies for this vulnerability require immediate implementation of Cisco IOS patches and updates as provided in the vendor security advisories. Network administrators should prioritize applying the relevant security updates to all affected devices running the vulnerable IOS versions. Additionally, implementing traffic shaping policies and rate limiting on T1/E1 interfaces can help reduce the likelihood of triggering the queue wedge condition. Network monitoring solutions should be enhanced to detect unusual queue behavior patterns that may indicate the onset of this vulnerability. Organizations should also consider implementing redundant interface configurations and failover mechanisms to maintain network availability during potential vulnerability exploitation events. The remediation process should include thorough testing of updated firmware in controlled environments before deployment to production networks. This vulnerability demonstrates the critical importance of maintaining up-to-date network infrastructure security measures and proper network traffic management policies.