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CIS Ubuntu 14.04 LTS - 2.3.4 Ensure telnet client is not installed

DevOps & Security
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Verify that the telnet client package is not installed

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How to use this skill

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  3. Review the proposed files and risks before you approve installation.
Prompt to paste
I want to install this Agent Skill for this project in Codex.

Source SKILL.md: https://github.com/CyberStrikeus/CyberStrike/blob/HEAD/.cyberstrike/skill/CIS_benchmarks/Operating_Systems/Ubuntu/CIS_Ubuntu_Linux_14.04_LTS_Benchmark_v2.1.0/cis-ubuntu1404-v210-2-3-4/SKILL.md

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First, summarize what it does, its dependencies, license status if identifiable, and any risks. Show the exact files you propose to add under .agents/skills/cis-ubuntu-14-04-lts-2-3-4-ensure-telnet-client-is-not-installed/. Do not write files or run scripts until I approve.

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Copying this prompt does not install or run the skill. Review third-party files before use. Codex skill guide

2.3.4 Ensure telnet client is not installed (Scored)

Profile Applicability

  • Level 1 - Server
  • Level 1 - Workstation

Description

The telnet package contains the telnet client, which allows users to start connections to other systems via the telnet protocol.

Rationale

The telnet protocol is insecure and unencrypted. The use of an unencrypted transmission medium could allow an unauthorized user to steal credentials. The ssh package provides an encrypted session and stronger security and is included in most Linux distributions.

Audit Procedure

Run the following command and verify telnet is not installed:

dpkg -s telnet

Expected Result

The command should indicate that the package is not installed (e.g., dpkg-query: package 'telnet' is not installed).

Remediation

Run the following command to uninstall telnet:

apt-get remove telnet

Default Value

telnet client may be installed by default.

Impact

Many insecure service clients are used as troubleshooting tools and in testing environments. Uninstalling them can inhibit capability to test and troubleshoot. If they are required it is advisable to remove the clients after use to prevent accidental or intentional misuse.

References

  • CIS Controls: 3.4 Use Only Secure Channels For Remote System Administration

Profile

  • Level 1 - Server
  • Level 1 - Workstation