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CIS Ubuntu 14.04 LTS - 2.1.8 Ensure telnet server is not enabled

DevOps & Security
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Verify that telnet inetd service is disabled to prevent cleartext credential exposure

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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-v210-2-1-8/SKILL.md

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2.1.8 Ensure telnet server is not enabled (Scored)

Profile Applicability

  • Level 1 - Server
  • Level 1 - Workstation

Description

The telnet-server package contains the telnet daemon, which accepts connections from users from other systems via the telnet protocol.

Rationale

The telnet protocol is insecure and unencrypted. The use of an unencrypted transmission medium could allow a user with access to sniff network traffic the ability to steal credentials. The ssh package provides an encrypted session and stronger security.

Audit Procedure

Verify the telnet service is not enabled. Run the following command and verify results are as indicated:

grep -R "^telnet" /etc/inetd.*

No results should be returned.

Check /etc/xinetd.conf and /etc/xinetd.d/* and verify all telnet services have disable = yes set.

Expected Result

No output should be returned from the grep command. All telnet services in xinetd should have disable = yes.

Remediation

Comment out or remove any lines starting with telnet from /etc/inetd.conf and /etc/inetd.d/*.

Set disable = yes on all telnet services in /etc/xinetd.conf and /etc/xinetd.d/*.

Default Value

telnet services are not enabled by default.

References

  • CIS Controls: 3.4 Use Only Secure Channels For Remote System Administration
  • CIS Controls: 9.1 Limit Open Ports, Protocols, and Services

Profile

  • Level 1 - Server
  • Level 1 - Workstation