CVE-2014-3353 in IOS XR
Summary
by MITRE
Cisco IOS XR 4.3(.2) and earlier, as used in Cisco Carrier Routing System (CRS), allows remote attackers to cause a denial of service (CPU consumption and IPv6 packet drops) via a malformed IPv6 packet, aka Bug ID CSCuo95165.
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Analysis
by VulDB Data Team • 06/05/2017
Cisco IOS XR software version 4.3.2 and earlier implementations within the Cisco Carrier Routing System CRS platform contain a critical vulnerability that enables remote attackers to execute denial of service attacks through carefully crafted malformed IPv6 packets. This vulnerability specifically affects the IPv6 packet processing functionality and results in excessive cpu utilization combined with significant packet drop rates, ultimately leading to service disruption. The flaw resides in how the system handles malformed IPv6 packets during the packet processing lifecycle, where insufficient input validation and error handling mechanisms fail to properly process malformed packet structures. The vulnerability impacts the carrier-grade routing infrastructure by consuming system resources at an accelerated rate, causing legitimate traffic to be dropped while the system becomes overwhelmed with processing the malformed packets. This issue represents a classic example of a resource exhaustion attack that leverages protocol parsing weaknesses to degrade system performance. The vulnerability has been assigned the bug ID CSCuo95165 and demonstrates a failure in input validation controls that aligns with CWE-129, which addresses improper validation of input ranges. From an operational security perspective, this vulnerability creates a significant risk for service providers who rely on the CRS platform for their core network infrastructure, as it can lead to widespread service disruption across multiple network segments. The attack vector is particularly concerning due to its remote nature, allowing adversaries to exploit the vulnerability from outside the network perimeter without requiring authentication or privileged access. The impact extends beyond simple service interruption as the excessive cpu consumption can affect other network services running on the same platform, creating cascading failures within the routing infrastructure. Organizations implementing the affected Cisco IOS XR versions should prioritize immediate patching to address this vulnerability, as the potential for widespread disruption makes this a high-priority security concern. The vulnerability also demonstrates characteristics consistent with ATT&CK technique T1498, which involves network denial of service attacks that consume system resources. This flaw highlights the importance of robust input validation and error handling in network infrastructure software, particularly in carrier-grade systems where reliability and uptime are paramount. The specific nature of the vulnerability suggests that the system lacks proper bounds checking and malformed packet handling routines, which are essential components of secure network protocol implementation. Network administrators should implement monitoring solutions to detect unusual cpu utilization patterns and packet drop rates that may indicate exploitation attempts. The vulnerability serves as a reminder of the critical need for regular security updates and vulnerability assessments in network infrastructure, particularly in systems that handle high volumes of traffic and support mission-critical communications. Organizations should also consider implementing network segmentation and access controls to limit the potential impact of such vulnerabilities, while maintaining comprehensive incident response procedures to address exploitation attempts. The affected Cisco IOS XR versions represent a significant security gap in the carrier routing ecosystem, where the combination of remote exploitability and resource exhaustion capabilities creates a particularly dangerous threat scenario for network service providers.