RHEL 8 must ensure the SSH server uses strong entropy.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-230253 | RHEL-08-010292 | SV-230253r1044799_rule | CCI-000366 | low |
| Description | ||||
| The most important characteristic of a random number generator is its randomness, namely its ability to deliver random numbers that are impossible to predict. Entropy in computer security is associated with the unpredictability of a source of randomness. The random source with high entropy tends to achieve a uniform distribution of random values. Random number generators are one of the most important building blocks of cryptosystems. The SSH implementation in RHEL 8 uses the OPENSSL library, which does not use high-entropy sources by default. By using the SSH_USE_STRONG_RNG environment variable the OPENSSL random generator is reseeded from /dev/random. This setting is not recommended on computers without the hardware random generator because insufficient entropy causes the connection to be blocked until enough entropy is available. | ||||
| STIG | Date | |||
| Red Hat Enterprise Linux 8 Security Technical Implementation Guide | 2025-05-14 | |||
Related Frameworks
4 paths across 3 frameworks
Related Frameworks
NIST 800-531 mapping
CM-6
1.00
- DISA · 2 · disa_xccdf · related
- DISA · 2025-01-23 · disa_cci_list · equivalent
NIST 800-1712 mappings
3.4.1
1.00
- DISA · 2 · disa_xccdf · related
- DISA · 2025-01-23 · disa_cci_list · equivalent
- NIST · Rev 2 (Feb 2020, errata Jan 2021) · nist_800_171_app_d · equivalent
3.4.2
1.00
- DISA · 2 · disa_xccdf · related
- DISA · 2025-01-23 · disa_cci_list · equivalent
- NIST · Rev 2 (Feb 2020, errata Jan 2021) · nist_800_171_app_d · equivalent
CCI1 mapping
CCI-000366
1.00
- DISA · 2 · disa_xccdf · related
Details
Check Text (C-230253r1044799_chk)
Note: If the operating system is RHEL versions 8.0 or 8.1, this requirement is not applicable.
Verify the operating system SSH server uses strong entropy with the following command:
$ sudo grep -i ssh_use_strong_rng /etc/sysconfig/sshd
SSH_USE_STRONG_RNG=32
If the "SSH_USE_STRONG_RNG" line does not equal "32", is commented out, or is missing, this is a finding.
Fix Text (F-32897r1044798_fix)
Configure the operating system SSH server to use strong entropy.
Add or modify the following line in the "/etc/sysconfig/sshd" file.
SSH_USE_STRONG_RNG=32
The SSH service must be restarted for changes to take effect.
Restart the SSH Daemon with the following command:
$ sudo systemctl restart sshd.service