Check: ACF2-SH-000050
IBM z/OS ACF2 STIG:
ACF2-SH-000050
(in versions v8 r15 through v7 r1)
Title
IBM z/OS SSH daemon must be configured to use a FIPS 140-2 compliant cryptographic algorithm. (Cat I impact)
Discussion
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, non-organization-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
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 lines 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-223589r918616_rule
Vulnerability ID: V-223589
Group Title: SRG-OS-000033-GPOS-00014
Expert Comments
CCIs
| Number | Definition |
|---|---|
| CCI-000068 |
The information system implements cryptographic mechanisms to protect the confidentiality of remote access sessions. |
| CCI-000803 |
The information system implements mechanisms for authentication to a cryptographic module that meet the requirements of applicable federal laws, Executive Orders, directives, policies, regulations, standards, and guidance for such authentication. |
| CCI-001453 |
The information system implements cryptographic mechanisms to protect the integrity of remote access sessions. |