CVE-2017-3879 in NX-OS
Summary
by MITRE
A Denial of Service vulnerability in the remote login functionality for Cisco NX-OS Software running on Cisco Nexus 9000 Series Switches could allow an unauthenticated, remote attacker to cause a process used for login to terminate unexpectedly and the login attempt to fail. There is no impact to user traffic flowing through the device. The attacker could use either a Telnet or an SSH client for the remote login attempt. Affected Products: This vulnerability affects Cisco Nexus 9000 Series Switches that are running Cisco NX-OS Software and are configured to allow remote Telnet connections to the device. More Information: CSCuy25824. Known Affected Releases: 7.0(3)I3(1) 8.3(0)CV(0.342) 8.3(0)CV(0.345). Known Fixed Releases: 8.3(0)CV(0.362) 8.0(1) 7.0(3)IED5(0.19) 7.0(3)IED5(0) 7.0(3)I4(1) 7.0(3)I4(0.8) 7.0(3)I2(2e) 7.0(3)F1(1.22) 7.0(3)F1(1) 7.0(3)F1(0.230).
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Analysis
by VulDB Data Team • 12/25/2024
This vulnerability represents a denial of service condition within the remote authentication subsystem of Cisco NX-OS software running on Nexus 9000 Series switches. The flaw specifically targets the login process functionality, creating a scenario where an unauthenticated remote attacker can deliberately cause authentication processes to terminate unexpectedly. The vulnerability affects both Telnet and SSH protocols, providing attackers with multiple vectors for exploitation. The affected software versions span across multiple release branches including 7.0(3)I3(1), 8.3(0)CV(0.342), and 8.3(0)CV(0.345), indicating the issue persisted across several software iterations. The vulnerability classification aligns with CWE-400, which addresses unspecified errors in resource management, and specifically relates to process termination anomalies in authentication services.
The technical implementation of this vulnerability exploits weaknesses in the authentication service handling mechanisms within the NX-OS software stack. When an attacker initiates a remote login attempt through either Telnet or SSH protocols, the system's authentication process becomes susceptible to unexpected termination. This occurs due to improper handling of authentication requests that leads to process crashes or forced terminations. The system's failure to properly validate or handle malformed authentication requests results in service disruption rather than allowing legitimate users to access the device. This behavior demonstrates a classic denial of service vector where legitimate service availability is compromised through manipulation of the authentication subsystem. The vulnerability does not impact data traffic flowing through the device, which means network performance and data integrity remain unaffected, but authentication services become unavailable.
The operational impact of this vulnerability creates significant security implications for network infrastructure management. Organizations relying on Nexus 9000 switches for their network core infrastructure face potential service disruption when attackers exploit this vulnerability. The unauthenticated nature of the attack means that even without prior credentials or access, malicious actors can effectively deny legitimate users access to the switch management interfaces. This vulnerability particularly impacts network administrators who depend on remote access for device management and monitoring operations. The attack vector allows for remote exploitation without requiring physical access or elevated privileges, making it particularly dangerous in environments where network devices are exposed to untrusted networks. The disruption affects both Telnet and SSH access methods, providing attackers with flexible options for exploitation.
Mitigation strategies for this vulnerability involve implementing the patched software versions provided by Cisco, specifically targeting the fixed releases including 8.3(0)CV(0.362), 8.0(1), and various 7.0(3)I4 and 7.0(3)F1 releases. Organizations should prioritize immediate deployment of these patches across all affected Nexus 9000 Series switches in their network infrastructure. Network segmentation and access control measures should be implemented to limit exposure of management interfaces to trusted networks only. Monitoring systems should be configured to detect unusual authentication patterns or process termination events that may indicate exploitation attempts. Additionally, implementing strong network access controls and restricting management access to specific IP addresses or ranges can reduce the attack surface. The vulnerability's alignment with ATT&CK technique T1110.003 for credential access and T1499.004 for network denial of service provides guidance for threat detection and response planning. Regular vulnerability assessments and security audits should be conducted to identify and remediate similar issues within the network infrastructure.