SLEM 5, for PKI-based authentication, must enforce authorized access to the corresponding private key.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-261342	SRG-OS-000067-GPOS-00035	SLEM-05-255085	SV-261342r996488_rule	2024-06-04	1

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 nonrepudiation 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 nonrepudiation 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.

ℹ️ Check
Verify the SSH private key files have a passcode. For each private key stored on the system, use the following command (with the example of "/etc/ssh/ssh_host_dsa_key"): > ssh-keygen -y -f /etc/ssh/ssh_host_dsa_key Load key "/etc/ssh/ssh_host_dsa_key": Permission denied If the contents of any key are displayed, this is a finding.

✔️ Fix
Create a new private and public key pair that uses a passcode with the following command: > sudo ssh-keygen -n <passphrase>