Telnet: 23

Security Weaknesses

• Transmits all data, including credentials, in plaintext.

• Susceptible to MITM (man-in-the-middle) attacks.

• Deprecated and insecure for modern use.

Security Defense and Mitigation Measures

• Replace Telnet with SSH for secure remote access.

• Disable Telnet services on servers and devices.

• Monitor for any unencrypted traffic on port 23 (TCP).

Indicators of Compromise or Attack

• Active Telnet sessions or unencrypted traffic on port 23.

• Failed login attempts indicating brute force attacks.

• Unauthorized system changes made via Telnet sessions.