The ESXi host SSH daemon must use DoD-approved encryption to protect the confidentiality of remote access sessions.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-207611	ESXI-65-000010	SV-207611r766919_rule		Medium

Description
Approved algorithms should impart some level of confidence in their implementation. Limit the ciphers to those algorithms which are FIPS-approved. Counter (CTR) mode is also preferred over cipher-block chaining (CBC) mode. Note: This does not imply FIPS 140-2 validation.

STIG	Date
VMware vSphere 6.5 ESXi Security Technical Implementation Guide	2021-09-22

Details

Check Text ( C-7866r766917_chk )
Only FIPS-approved ciphers should be used. To verify that only FIPS-approved ciphers are in use, run the following command from an SSH session connected to the ESXi host, or from the ESXi shell: # grep -i "^Ciphers" /etc/ssh/sshd_config If there is no output or the output is not exactly "Ciphers aes256-ctr,aes192-ctr,aes128-ctr", this is a finding.

Fix Text (F-7866r766918_fix)
Limit the ciphers to those algorithms which are FIPS-approved. Counter (CTR) mode is also preferred over cipher-block chaining (CBC) mode. From an SSH session connected to the ESXi host, or from the ESXi shell, add or correct the following line in "/etc/ssh/sshd_config": Ciphers aes256-ctr,aes192-ctr,aes128-ctr