Description

The telnet-server package can be removed with the following command:

$ sudo yum erase telnet-server

Rationale

It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities are often overlooked and therefore may remain unsecure. They increase the risk to the platform by providing additional attack vectors.

The telnet service provides an unencrypted remote access service which does not provide for the confidentiality and integrity of user passwords or the remote session. If a privileged user were to login using this service, the privileged user password could be compromised.

Removing the telnet-server package decreases the risk of the telnet service’s accidental (or intentional) activation.

Remediation

Shell script

The following script can be run on the host to remediate the issue.

#!/bin/bash

# CAUTION: This remediation script will remove telnet-server
#	   from the system, and may remove any packages
#	   that depend on telnet-server. Execute this
#	   remediation AFTER testing on a non-production
#	   system!

if rpm -q --quiet "telnet-server" ; then

    yum remove -y "telnet-server"

fi

Ansible playbook

The following playbook can be run with Ansible to remediate the issue.

- name: Ensure telnet-server is removed
  package:
    name: telnet-server
    state: absent
  tags:
  - CCE-27165-0
  - DISA-STIG-RHEL-07-021710
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - PCI-DSS-Req-2.2.2
  - PCI-DSSv4-2.2.4
  - disable_strategy
  - high_severity
  - low_complexity
  - low_disruption
  - no_reboot_needed
  - package_telnet-server_removed