STIGQter: STIG Summary: Red Hat Enterprise Linux 8 Security Technical Implementation Guide Version: 1 Release: 2 Benchmark Date: 23 Apr 2021:

The RHEL 8 operating system must implement DoD-approved encryption to protect the confidentiality of SSH connections.

DISA Rule

SV-230252r646869_rule

Vulnerability Number

V-230252

Group Title

SRG-OS-000250-GPOS-00093

Rule Version

RHEL-08-010291

Severity

CAT II

CCI(s)

• CCI-001453 - The information system implements cryptographic mechanisms to protect the integrity of remote access sessions.

Weight

10

Fix Recommendation

Configure the RHEL 8 SSH daemon to use only ciphers employing FIPS 140-2-approved algorithms with the following command:

$ sudo fips-mode-setup --enable

Next, update the "/etc/crypto-policies/back-ends/openssh.config" and "/etc/crypto-policies/back-ends/opensshserver.config" files to include these ciphers employing FIPS 140-2-approved algorithms:

/etc/crypto-policies/back-ends/openssh.config:Ciphers aes256-ctr,aes192-ctr,aes128-ctr
/etc/crypto-policies/back-ends/opensshserver.config:CRYPTO_POLICY='-oCiphers=aes256-ctr,aes192-ctr,aes128-ctr'
/etc/crypto-policies/back-ends/opensshserver.config:CRYPTO_POLICY='-oCiphers=aes256-ctr,aes192-ctr,aes128-ctr'

A reboot is required for the changes to take effect.

Check Contents

Verify the SSH daemon is configured to use only ciphers employing FIPS 140-2-approved algorithms:

Verify that system-wide crypto policies are in effect:

$ sudo grep -i crypto_policy /etc/sysconfig/sshd

# crypto_policy=

If the "crypto_policy" is uncommented, this is a finding.

Verify which system-wide crypto policy is in use:

$ sudo update-crypto-policies --show

FIPS

Check that the ciphers in the back-end configurations are FIPS 140-2-approved algorithms with the following command:

$ sudo grep -i ciphers /etc/crypto-policies/back-ends/openssh.config /etc/crypto-policies/back-ends/opensshserver.config

/etc/crypto-policies/back-ends/openssh.config:Ciphers aes256-ctr,aes192-ctr,aes128-ctr
/etc/crypto-policies/back-ends/opensshserver.config:CRYPTO_POLICY='-oCiphers=aes256-ctr,aes192-ctr,aes128-ctr'
/etc/crypto-policies/back-ends/opensshserver.config:CRYPTO_POLICY='-oCiphers=aes256-ctr,aes192-ctr,aes128-ctr'

If the cipher entries in the "openssh.config" and "opensshserver.config" files have any ciphers other than "aes256-ctr,aes192-ctr,aes128-ctr", the order differs from the example above, if they are missing, or commented out, this is a finding.

Vulnerability Number

V-230252

Documentable

False

Rule Version

RHEL-08-010291

Severity Override Guidance

Verify the SSH daemon is configured to use only ciphers employing FIPS 140-2-approved algorithms:

Verify that system-wide crypto policies are in effect:

$ sudo grep -i crypto_policy /etc/sysconfig/sshd

# crypto_policy=

If the "crypto_policy" is uncommented, this is a finding.

Verify which system-wide crypto policy is in use:

$ sudo update-crypto-policies --show

FIPS

Check that the ciphers in the back-end configurations are FIPS 140-2-approved algorithms with the following command:

$ sudo grep -i ciphers /etc/crypto-policies/back-ends/openssh.config /etc/crypto-policies/back-ends/opensshserver.config

/etc/crypto-policies/back-ends/openssh.config:Ciphers aes256-ctr,aes192-ctr,aes128-ctr
/etc/crypto-policies/back-ends/opensshserver.config:CRYPTO_POLICY='-oCiphers=aes256-ctr,aes192-ctr,aes128-ctr'
/etc/crypto-policies/back-ends/opensshserver.config:CRYPTO_POLICY='-oCiphers=aes256-ctr,aes192-ctr,aes128-ctr'

If the cipher entries in the "openssh.config" and "opensshserver.config" files have any ciphers other than "aes256-ctr,aes192-ctr,aes128-ctr", the order differs from the example above, if they are missing, or commented out, this is a finding.

Check Content Reference

M

Target Key

2921

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