The Red Hat Enterprise Linux operating system must use a FIPS 140-2 approved cryptographic algorithm for SSH communications.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-72221	RHEL-07-040110	SV-86845r3_rule		Medium

Description
Unapproved mechanisms that are used for authentication to the cryptographic module are not verified and therefore cannot be relied upon to provide confidentiality or integrity, and DoD data may be compromised. Operating systems utilizing encryption are required to use FIPS-compliant mechanisms for authenticating to cryptographic modules. FIPS 140-2 is the current standard for validating that mechanisms used to access cryptographic modules utilize authentication that meets DoD requirements. This allows for Security Levels 1, 2, 3, or 4 for use on a general purpose computing system. Satisfies: SRG-OS-000033-GPOS-00014, SRG-OS-000120-GPOS-00061, SRG-OS-000125-GPOS-00065, SRG-OS-000250-GPOS-00093, SRG-OS-000393-GPOS-00173

Description

Unapproved mechanisms that are used for authentication to the cryptographic module are not verified and therefore cannot be relied upon to provide confidentiality or integrity, and DoD data may be compromised. Operating systems utilizing encryption are required to use FIPS-compliant mechanisms for authenticating to cryptographic modules. FIPS 140-2 is the current standard for validating that mechanisms used to access cryptographic modules utilize authentication that meets DoD requirements. This allows for Security Levels 1, 2, 3, or 4 for use on a general purpose computing system. Satisfies: SRG-OS-000033-GPOS-00014, SRG-OS-000120-GPOS-00061, SRG-OS-000125-GPOS-00065, SRG-OS-000250-GPOS-00093, SRG-OS-000393-GPOS-00173

STIG	Date
Red Hat Enterprise Linux 7 Security Technical Implementation Guide	2018-11-28

Details

Check Text ( C-72455r4_chk )
Verify the operating system uses mechanisms meeting the requirements of applicable federal laws, Executive orders, directives, policies, regulations, standards, and guidance for authentication to a cryptographic module. Note: If RHEL-07-021350 is a finding, this is automatically a finding as the system cannot implement FIPS 140-2-approved cryptographic algorithms and hashes. The location of the "sshd_config" file may vary if a different daemon is in use. Inspect the "Ciphers" configuration with the following command: # grep -i ciphers /etc/ssh/sshd_config Ciphers aes128-ctr,aes192-ctr,aes256-ctr If any ciphers other than "aes128-ctr", "aes192-ctr", or "aes256-ctr" are listed, the "Ciphers" keyword is missing, or the returned line is commented out, this is a finding.

Check Text ( C-72455r4_chk )

Verify the operating system uses mechanisms meeting the requirements of applicable federal laws, Executive orders, directives, policies, regulations, standards, and guidance for authentication to a cryptographic module.

Note: If RHEL-07-021350 is a finding, this is automatically a finding as the system cannot implement FIPS 140-2-approved cryptographic algorithms and hashes.

The location of the "sshd_config" file may vary if a different daemon is in use.

Inspect the "Ciphers" configuration with the following command:

# grep -i ciphers /etc/ssh/sshd_config
Ciphers aes128-ctr,aes192-ctr,aes256-ctr

If any ciphers other than "aes128-ctr", "aes192-ctr", or "aes256-ctr" are listed, the "Ciphers" keyword is missing, or the returned line is commented out, this is a finding.

Fix Text (F-78575r3_fix)
Configure SSH to use FIPS 140-2 approved cryptographic algorithms. Add the following line (or modify the line to have the required value) to the "/etc/ssh/sshd_config" file (this file may be named differently or be in a different location if using a version of SSH that is provided by a third-party vendor). Ciphers aes128-ctr,aes192-ctr,aes256-ctr The SSH service must be restarted for changes to take effect.

Fix Text (F-78575r3_fix)

Configure SSH to use FIPS 140-2 approved cryptographic algorithms.

Add the following line (or modify the line to have the required value) to the "/etc/ssh/sshd_config" file (this file may be named differently or be in a different location if using a version of SSH that is provided by a third-party vendor).

Ciphers aes128-ctr,aes192-ctr,aes256-ctr

The SSH service must be restarted for changes to take effect.