IBM z/OS SSH daemon must be configured to use a FIPS 140-3-compliant cryptographic algorithm.

Without confidentiality protection mechanisms, unauthorized individuals may gain access to sensitive information via a remote access session.

Remote access is access to DoW nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless.

Encryption provides a means to secure the remote connection to prevent unauthorized access to the data traversing the remote access connection (e.g., RDP), thereby providing a degree of confidentiality. The encryption strength of a mechanism is selected based on the security categorization of the information.

Satisfies: SRG-OS-000033-GPOS-00014, SRG-OS-000120-GPOS-00061

Locate the SSH daemon configuration file, which may be found in "/etc/ssh/" directory.

Alternately:

From the UNIX System Services ISPF Shell, navigate to ribbon select tools.

Select option 1 - Work with Processes.

If SSH Daemon is not active, this is not a finding.

Examine the SSH daemon configuration file: sshd_config

If there are no ciphers lines, or the ciphers list contains any cipher not starting with "aes", this is a finding.

If the MACs line is not configured to "hmac-sha1" or greater, this is a finding.

Examine the z/OS-specific sshd server systemwide configuration: zos_sshd_config

If any of the following is untrue, this is a finding:

FIPSMODE=YES CiphersSource=ICSF MACsSource=ICSF

Edit the SSH daemon configuration and remove any ciphers not starting with "aes". If necessary, add a "Ciphers" line using FIPS 140-3-compliant algorithms.

Configure for message authentication to MACs "hmac-sha1" or greater.

Edit the z/OS-specific sshd server systemwide configuration file configuration as follows: FIPSMODE=YES CiphersSource=ICSF MACsSource=ICSF