CVE-2014-3379 in IOS XR
Summary
by MITRE
Cisco IOS XR 5.1 and earlier on Network Convergence System 6000 devices allows remote attackers to cause a denial of service (NPU and card hang or reload) via a malformed MPLS packet, aka Bug ID CSCuq10466.
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Analysis
by VulDB Data Team • 06/06/2017
Cisco IOS XR 5.1 and earlier versions running on Network Convergence System 6000 devices contain a critical vulnerability that enables remote attackers to induce denial of service conditions through carefully crafted malformed MPLS packets. This vulnerability specifically affects the Network Processing Unit and line card components of the system, potentially causing complete system hang or forced reloads that disrupt network operations. The flaw resides in the packet processing logic where the system fails to properly validate incoming MPLS packet structures, leading to unpredictable behavior when encountering malformed data. According to the Cisco bug ID CSCuq10466, this issue represents a fundamental failure in input validation and error handling mechanisms within the IOS XR operating system. The vulnerability is particularly concerning because it operates at the network processing level, affecting core infrastructure components that maintain network connectivity and routing functions. Attackers can exploit this weakness by sending specifically crafted MPLS packets that trigger buffer overflows or state machine corruption within the NPU, ultimately leading to system instability. The impact extends beyond simple service disruption as these device reloads can cause temporary network outages affecting multiple services and potentially creating cascading failures in interconnected network systems.
The technical nature of this vulnerability aligns with CWE-129, Input Validation, and CWE-125, Out-of-bounds Read, as the system does not properly validate the bounds of incoming MPLS packet data structures. The flaw also demonstrates characteristics of CWE-248, Uncaught Exception, where the system fails to properly handle malformed input data during packet processing operations. From an operational perspective, this vulnerability creates significant risk for network infrastructure administrators who must maintain high availability and reliability standards for their services. The attack vector is particularly dangerous because it requires no authentication credentials and can be executed from remote locations, making it an attractive target for malicious actors seeking to disrupt network services. The vulnerability affects the core routing and switching capabilities of the Network Convergence System 6000, which typically serves as critical backbone infrastructure for telecommunications and enterprise networks. When exploited, the vulnerability causes the NPU to enter an unrecoverable state, forcing automatic system reloads that can last several minutes and result in temporary loss of network connectivity for all services relying on these devices.
Mitigation strategies for CVE-2014-3379 should focus on immediate patch deployment and network segmentation approaches to limit potential attack surface. Cisco released IOS XR software updates addressing this vulnerability, and administrators should prioritize applying these patches to all affected devices. Network monitoring solutions should be configured to detect and alert on unusual MPLS packet patterns that may indicate exploitation attempts. The implementation of ingress filtering and packet validation mechanisms can help reduce the risk of successful attacks by dropping malformed packets before they reach vulnerable processing units. From an ATT&CK framework perspective, this vulnerability maps to T1059 Command and Scripting Interpreter and T1499 Endpoint Denial of Service, as it enables attackers to perform remote denial of service operations against network infrastructure. Organizations should also implement comprehensive network access control policies to limit exposure of these devices to untrusted networks, while maintaining detailed logging of all MPLS traffic for forensic analysis. Regular vulnerability assessments and penetration testing should be conducted to identify similar weaknesses in network infrastructure components and ensure that security controls remain effective against evolving threat landscapes.