IBM z/OS SSH daemon must be configured to use a FIPS 140-2 compliant cryptographic algorithm.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-223589 | ACF2-SH-000050 | SV-223589r1083012_rule | CCI-000068 | high |
| Description | ||||
| Without confidentiality protection mechanisms, unauthorized individuals may gain access to sensitive information via a remote access session. Remote access is access to DOD 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 | ||||
| STIG | Date | |||
| IBM z/OS ACF2 Security Technical Implementation Guide | 2025-06-24 | |||
Details
Check Text (C-223589r1083012_chk)
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 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
Fix Text (F-25250r1082840_fix)
Edit the SSH daemon configuration and remove any ciphers not starting with "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