AIX SSH private host key files must have mode 0600 or less permissive.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-91279	AIX7-00-003004	SV-101377r1_rule		Medium

Description
If the private key is discovered, an attacker can use the key to authenticate as an authorized user and gain access to the network infrastructure. The cornerstone of the PKI is the private key used to encrypt or digitally sign information. If the private key is stolen, this will lead to the compromise of the authentication and non-repudiation gained through PKI because the attacker can use the private key to digitally sign documents and pretend to be the authorized user. Both the holders of a digital certificate and the issuing authority must protect the computers, storage devices, or whatever they use to keep the private keys.

Description

If the private key is discovered, an attacker can use the key to authenticate as an authorized user and gain access to the network infrastructure. The cornerstone of the PKI is the private key used to encrypt or digitally sign information. If the private key is stolen, this will lead to the compromise of the authentication and non-repudiation gained through PKI because the attacker can use the private key to digitally sign documents and pretend to be the authorized user. Both the holders of a digital certificate and the issuing authority must protect the computers, storage devices, or whatever they use to keep the private keys.

STIG	Date
IBM AIX 7.x Security Technical Implementation Guide	2020-02-24

Details

Check Text ( C-90433r1_chk )
Check the permissions for SSH private host key files: # ls -lL /etc/ssh/*key The above command should yield the following output: -rw------- 1 root system 668 Jan 18 2017 /etc/ssh/ssh_host_dsa_key -rw------- 1 root system 227 Jan 18 2017 /etc/ssh/ssh_host_ecdsa_key -rw------- 1 root system 965 Jan 18 2017 /etc/ssh/ssh_host_key -rw------- 1 root system 1675 Jan 18 2017 /etc/ssh/ssh_host_rsa_key If any file has a mode more permissive than "0600", this is a finding.

Check Text ( C-90433r1_chk )

Check the permissions for SSH private host key files:
# ls -lL /etc/ssh/*key

The above command should yield the following output:
-rw------- 1 root system 668 Jan 18 2017 /etc/ssh/ssh_host_dsa_key
-rw------- 1 root system 227 Jan 18 2017 /etc/ssh/ssh_host_ecdsa_key
-rw------- 1 root system 965 Jan 18 2017 /etc/ssh/ssh_host_key
-rw------- 1 root system 1675 Jan 18 2017 /etc/ssh/ssh_host_rsa_key

If any file has a mode more permissive than "0600", this is a finding.

Fix Text (F-97477r1_fix)
Change the permissions for the SSH private host key files: # chmod 0600 /etc/ssh/*key