CVE-2014-0677 in NX-OS
Summary
by MITRE
The Label Distribution Protocol (LDP) functionality in Cisco NX-OS allows remote attackers to cause a denial of service (temporary LDP session outage) via LDP discovery traffic containing malformed Hello messages, aka Bug ID CSCul88851.
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Analysis
by VulDB Data Team • 06/08/2021
The vulnerability described in CVE-2014-0677 represents a critical flaw in Cisco NX-OS software that affects the Label Distribution Protocol implementation. This issue specifically targets the LDP discovery mechanism which is fundamental to MPLS network operations, where routers use Hello messages to establish and maintain neighbor relationships. The vulnerability arises from insufficient input validation within the LDP processing code, allowing malicious actors to craft specially crafted Hello messages that trigger unexpected behavior in the affected network devices.
The technical exploitation of this vulnerability occurs through the injection of malformed Hello messages during the LDP discovery phase. When the NX-OS device receives these crafted packets, the parsing logic fails to properly handle the malformed data structures, leading to a temporary disruption of LDP sessions. This results in a denial of service condition where the affected router temporarily loses its ability to establish or maintain LDP neighbor relationships, effectively breaking MPLS forwarding for the impacted network segment. The vulnerability is classified under CWE-129 Input Validation and is particularly concerning because it operates at the network protocol level, affecting core routing functionality.
From an operational impact perspective, this vulnerability poses significant risks to network availability and stability. Organizations relying on MPLS networks for critical traffic routing may experience service disruption when attackers exploit this weakness, potentially leading to widespread connectivity issues across the affected network infrastructure. The temporary nature of the outage means that while the impact is not permanent, the frequency of exploitation can create ongoing service degradation. This vulnerability aligns with ATT&CK technique T1498 Network Denial of Service, specifically targeting network infrastructure components that are essential for normal network operations.
Mitigation strategies for this vulnerability include applying the official Cisco security patches and updates that address the input validation issues in the LDP implementation. Network administrators should also implement monitoring solutions to detect anomalous LDP Hello message patterns that could indicate exploitation attempts. Additionally, implementing access control measures to restrict LDP discovery traffic to trusted sources can provide an additional layer of protection. Organizations should consider network segmentation approaches that limit the impact scope of such attacks and establish incident response procedures specifically designed to handle LDP-related service disruptions. The vulnerability highlights the importance of robust input validation in network protocol implementations and underscores the need for continuous security assessment of core network functions.