cyberstrikeus CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0 - Control 5.3.4
Description
SSH supports two different and incompatible protocols: SSH1 and SSH2. SSH1 was the original protocol and was subject to security issues. SSH2 is more advanced and secure.
Rationale
SSH v1 suffers from insecurities that do not affect SSH v2.
Audit Procedure
Command Line
Run the following command and verify that output matches:
sshd -T -C user=root -C host="$(hostname)" -C addr="$(grep $(hostname) /etc/hosts | awk '{print $1}')" | grep '^\s*protocol'
Expected Result
protocol 2
Run the following command and verify the output:
grep -Ei '^\s*Protocol\s+[^2].*$' /etc/ssh/sshd_config
Nothing should be returned.
Remediation
Command Line
Edit the /etc/ssh/sshd_config file to set the parameter as follows:
Protocol 2
Default Value
Protocol 2
References
- SSHD_CONFIG(5)
CIS Controls
Version 7
9.2 Ensure Only Approved Ports, Protocols and Services Are Running - Ensure that only network ports, protocols, and services listening on a system with validated business needs, are running on each system.
Profile Applicability
- Level 1 - Server
- Level 1 - Workstation
Assessment Status
Automated