CVE-2017-12355 in IOS XR
Summary
by MITRE
A vulnerability in the Local Packet Transport Services (LPTS) ingress frame-processing functionality of Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause one of the LPTS processes on an affected system to restart unexpectedly, resulting in a brief denial of service (DoS) condition. The vulnerability is due to incomplete LPTS frame validation by the affected software. An attacker could exploit this vulnerability by sending crafted XML requests to the management interface of an affected system. A successful exploit could allow the attacker to cause one of the LPTS processes on the affected system to restart unexpectedly, which would impact LPTS traffic and cause a brief DoS condition while the process restarts. Cisco Bug IDs: CSCvf76332.
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Analysis
by VulDB Data Team • 01/25/2021
The vulnerability described in CVE-2017-12355 represents a critical denial of service weakness within Cisco IOS XR Software's Local Packet Transport Services implementation. This flaw specifically targets the ingress frame-processing functionality of LPTS, which serves as a crucial component for handling packet transport operations in network infrastructure devices. The vulnerability stems from insufficient validation mechanisms within the LPTS frame processing pipeline, creating an exploitable condition that can be leveraged by remote attackers without requiring authentication credentials. The affected system operates within a network environment where management interfaces are accessible, making the device susceptible to external exploitation attempts.
The technical exploitation mechanism involves sending specially crafted XML requests to the management interface of the vulnerable Cisco IOS XR device. This particular attack vector demonstrates a classic input validation flaw where the system fails to properly sanitize or verify the structure and content of incoming XML data before processing it within the LPTS framework. The incomplete validation allows malicious payloads to bypass normal processing checks, leading to unexpected behavior within the LPTS processes. This type of vulnerability aligns with CWE-20, which categorizes improper input validation as a fundamental weakness in software security design. The XML parsing and processing within the management interface creates an attack surface where malformed data can trigger unexpected system behavior rather than being properly rejected or handled gracefully.
The operational impact of this vulnerability manifests as an unexpected restart of critical LPTS processes on the affected system, resulting in temporary service disruption. During the process restart interval, LPTS traffic experiences interruption, creating a brief but noticeable denial of service condition that affects network packet transport operations. This disruption can have cascading effects throughout the network infrastructure, particularly in environments where LPTS services are critical for maintaining network connectivity and traffic management functions. The vulnerability's remote nature means that attackers can exploit it from outside the network perimeter, making it particularly dangerous for devices that expose management interfaces to untrusted networks or the internet. The attack does not require privileged access or sophisticated techniques, making it accessible to a broad range of threat actors and increasing the potential for widespread impact.
Security mitigations for this vulnerability should prioritize immediate patch deployment from Cisco, addressing the root cause through proper XML validation implementation within the LPTS frame processing components. Network administrators should implement restrictive access controls on management interfaces, limiting access to trusted networks and implementing strong authentication mechanisms. The principle of least privilege should be applied to management interface access, ensuring that only authorized personnel can interact with the system's configuration and operational interfaces. Additionally, network segmentation strategies should be employed to isolate critical infrastructure components and limit the potential blast radius of successful exploitation attempts. Monitoring and logging mechanisms should be enhanced to detect unusual traffic patterns or repeated connection attempts to management interfaces, which could indicate exploitation attempts. This vulnerability highlights the importance of input validation in network infrastructure software and demonstrates how seemingly minor validation gaps can result in significant operational disruptions, aligning with ATT&CK technique T1499 for network denial of service attacks.