Title

IBM z/OS must implement DoD-approved encryption to protect the confidentiality of remote access sessions. (Cat I impact)

Discussion

Without cryptographic integrity protections, information can be altered by unauthorized users without detection.

Check Content

Locate the SSH daemon configuration file, which may be found in /etc/ssh/ directory. Alternately: From 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 SSH daemon configuration file. sshd_config If there are no "Ciphers" line or the ciphers list contains any cipher not starting with "3des" or "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 system-wide configuration. zos_sshd_config If any of the following is untrue, this is a finding. FIPSMODE=YES CiphersSource=ICSF MACsSource=ICSF

Fix Text

Edit the SSH daemon configuration and remove any ciphers not starting with "3des" or "aes". If necessary, add a "Ciphers" line using FIPS 140-2 compliant algorithms. Configure for message authentication to MACs "hmac-sha1" or greater. Edit the z/OS-specific sshd server system-wide configuration file configuration as follows: FIPSMODE=YES CiphersSource=ICSF MACsSource=ICSF

Additional Identifiers

Rule ID: SV-223538r877394_rule

Vulnerability ID: V-223538

Group Title: SRG-OS-000250-GPOS-00093

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.