STIGQter: STIG Summary: Riverbed NetIM OS Security Technical Implementation Guide Version: 1 Release: 1 Benchmark Date: 11 Sep 2025:

Ubuntu OS SSH server must be configured to use only FIPS-validated key exchange algorithms.

DISA Rule

SV-275626r1147928_rule

Vulnerability Number

V-275626

Group Title

SRG-OS-000033-GPOS-00014

Rule Version

RIIM-OS-255060

Severity

CAT I

CCI(s)

• CCI-000068 - Implement cryptographic mechanisms to protect the confidentiality of remote access sessions.

Weight

10

Fix Recommendation

Configure the SSH server to use only FIPS-validated key exchange algorithms.

Add or modify the following line in the "/etc/ssh/sshd_config" file:

KexAlgorithms ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256

Restart the SSH server for changes to take effect:

$ sudo systemctl restart sshd.service

Check Contents

Verify that the SSH server is configured to use only FIPS-validated key exchange algorithms by using the following command:

$ sudo /usr/sbin/sshd -dd 2>&1 | awk '/filename/ {print $4}' | tr -d '\r' | tr '\n' ' ' | xargs sudo grep -iH 'kexalgorithms'
/etc/ssh/sshd_config:KexAlgorithms ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256

If "KexAlgorithms" does not contain only the algorithms "ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256" in exact order, is commented out, is missing, or conflicting results are returned, this is a finding.

Vulnerability Number

V-275626

Documentable

False

Rule Version

RIIM-OS-255060

Severity Override Guidance

Verify that the SSH server is configured to use only FIPS-validated key exchange algorithms by using the following command:

$ sudo /usr/sbin/sshd -dd 2>&1 | awk '/filename/ {print $4}' | tr -d '\r' | tr '\n' ' ' | xargs sudo grep -iH 'kexalgorithms'
/etc/ssh/sshd_config:KexAlgorithms ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256

If "KexAlgorithms" does not contain only the algorithms "ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256" in exact order, is commented out, is missing, or conflicting results are returned, this is a finding.

Check Content Reference

M

Target Key

5706