Title

Amazon Linux 2023 SSHD must accept public key authentication. (Cat II impact)

Discussion

Without the use of multifactor authentication, the ease of access to privileged functions is greatly increased. Multifactor authentication requires using two or more factors to achieve authentication. Factors include: 1. Something a user knows (e.g., password/PIN); 2. Something a user has (e.g., cryptographic identification device, token); and 3. Something a user is (e.g., biometric). A privileged account is defined as an information system account with authorizations of a privileged user. Network access is defined as access to an information system by a user (or a process acting on behalf of a user) communicating through a network (e.g., local area network, wide area network, or the internet). The DOD Common Access Card (CAC) with DOD-approved PKI is an example of multifactor authentication. Satisfies: SRG-OS-000105-GPOS-00052, SRG-OS-000106-GPOS-00053, SRG-OS-000107-GPOS-00054, SRG-OS-000108-GPOS-00055

Check Content

Verify Amazon Linux 2023 is configured so that the SSH daemon accepts public key encryption with the following command: $ sudo grep -ir PubkeyAuthentication /etc/ssh/sshd_config /etc/ssh/sshd_config.d/ /etc/ssh/sshd_config:#PubkeyAuthentication yes /etc/ssh/sshd_config.d/90-PubkeyAuth:PubkeyAuthentication yes If "PubkeyAuthentication" is set to no, the line is commented out, or the line is missing, this is a finding.

Fix Text

Configure Amazon Linux 2023 to use public key authentication for SSHD by adding or modifying the following line in "/etc/ssh/sshd_config" or in a file in "/etc/ssh/sshd_config.d". PubkeyAuthentication yes Restart the SSH daemon for the settings to take effect: $ sudo systemctl restart sshd.service

Additional Identifiers

Rule ID: SV-274047r1120129_rule

Vulnerability ID: V-274047

Group Title: SRG-OS-000105-GPOS-00052

Expert Comments

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