CVE-2017-3878 : Security Advisory and Response

A vulnerability has been discovered in the Telnet remote login feature of Cisco NX-OS Software on Cisco Nexus 9000 Series Switches, potentially exploitable by unauthorized remote attackers.

Understanding CVE-2017-3878

This CVE involves a Denial of Service vulnerability in the Telnet remote login functionality of Cisco NX-OS Software on Cisco Nexus 9000 Series Switches.

What is CVE-2017-3878?

The vulnerability allows an unauthenticated remote attacker to terminate the Telnet process used for login, resulting in login failures without impacting user traffic.

The Impact of CVE-2017-3878

Unauthorized remote attackers can disrupt the Telnet login process on affected devices.
Login attempts may fail due to the exploitation of this vulnerability.

Technical Details of CVE-2017-3878

This section provides detailed technical information about the CVE.

Vulnerability Description

The vulnerability affects Cisco Nexus 9000 Series Switches running Cisco NX-OS Software with remote Telnet connections enabled.

Affected Systems and Versions

Affected Products: Cisco Nexus 9000 Series Switches running Cisco NX-OS Software configured for remote Telnet connections.
Known Affected Releases: 7.0(3)I3(0.170)
Known Fixed Releases: 7.0(3)I3(1), 7.0(3)I3(0.257), 7.0(3)I3(0.255), 7.0(3)I2(2e), 7.0(3)F1(1.22), 7.0(3)F1(1)

Exploitation Mechanism

Unauthorized remote attackers exploit the Telnet remote login feature to disrupt the login process, causing unexpected termination and login failures.

Mitigation and Prevention

Steps to address and prevent the CVE exploitation.

Immediate Steps to Take

Disable Telnet remote login on affected devices.
Implement firewall rules to restrict access to vulnerable services.
Monitor network traffic for any suspicious activity.

Long-Term Security Practices

Regularly update and patch Cisco NX-OS Software to the latest version.
Use secure remote access methods like SSH instead of Telnet.

Patching and Updates

Apply the recommended fixed releases provided by Cisco to address the vulnerability.