CVE-2018-0164 in IOS XE
Summary
by MITRE
A vulnerability in the Switch Integrated Security Features of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an interface queue wedge. The vulnerability is due to incorrect handling of crafted IPv6 packets. An attacker could exploit this vulnerability by sending crafted IPv6 packets through the device. An exploit could allow the attacker to cause an interface queue wedge. This vulnerability affects the Cisco cBR-8 Converged Broadband Router, Cisco ASR 1000 Series Aggregation Services Routers, and Cisco Cloud Services Router 1000V Series when configured with IPv6. In the field and internal testing, this vulnerability was only observed or reproduced on the Cisco cBR-8 Converged Broadband Router. The Cisco ASR 1000 Series Aggregation Services Routers and Cisco Cloud Services Router 1000V Series contain the same code logic, so affected trains have had the code fix applied; however, on these two products, the vulnerability has not been observed in the field or successfully reproduced internally. Cisco Bug IDs: CSCvd75185.
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Analysis
by VulDB Data Team • 01/17/2020
This vulnerability resides within the Switch Integrated Security Features of Cisco IOS XE Software and represents a significant security flaw that could enable remote attackers to disrupt network operations through carefully crafted IPv6 packet manipulation. The issue stems from improper handling of IPv6 packets within the router's interface queue management system, creating a condition where legitimate network traffic can become blocked or stalled. The vulnerability specifically affects the cBR-8 Converged Broadband Router, ASR 1000 Series Aggregation Services Routers, and Cloud Services Router 1000V Series when configured with IPv6 functionality. According to Cisco's internal testing and field observations, while the vulnerability exists in the codebase of all affected products, it has only been successfully demonstrated on the cBR-8 platform, suggesting potential product-specific implementation variations or differing attack surface characteristics.
The technical exploitation of this vulnerability occurs through the transmission of specially crafted IPv6 packets that trigger a queue wedge condition on network interfaces. This condition effectively causes the interface queue to become stuck or wedged, preventing normal packet processing and potentially leading to complete network disruption on the affected interfaces. The flaw demonstrates characteristics consistent with improper input validation and resource handling issues that fall under CWE-129, which deals with insufficient validation of the length of input data. From an operational perspective, this vulnerability creates a denial-of-service condition that could severely impact network availability and reliability, particularly in environments where continuous network connectivity is critical for business operations or infrastructure services.
The impact of this vulnerability extends beyond simple service disruption as it represents a potential attack vector that could be leveraged by malicious actors to create sustained network outages or to perform targeted disruption of specific network segments. Network administrators face the challenge of identifying and mitigating this vulnerability without disrupting legitimate network operations, particularly since the vulnerability only manifests under specific conditions involving crafted IPv6 traffic. The affected devices operate at the core of network infrastructure, making any disruption potentially cascading throughout the connected network topology. This vulnerability aligns with ATT&CK technique T1498 which covers network denial-of-service attacks, and T1071.004 which addresses application layer protocol: dns, indicating that attackers could potentially leverage this weakness to create broader network disruption effects.
Cisco has addressed this vulnerability through software updates and patches specifically targeting the affected code logic within the IOS XE software. The company has identified that while all three affected product lines contain the vulnerable code, only the cBR-8 platform has demonstrated the actual exploitable condition in practice. Organizations should prioritize applying the relevant security patches and updates to their affected Cisco devices, particularly those operating in environments where network availability is critical. Network monitoring should be enhanced to detect unusual traffic patterns or interface queue conditions that might indicate exploitation attempts, and security teams should implement proper network segmentation to limit the potential impact of such attacks. The vulnerability serves as a reminder of the importance of robust input validation in network infrastructure software and demonstrates how seemingly minor implementation flaws can create significant operational risks in critical network equipment.