PostgreSQL, when using PKI-based authentication, must validate certificates by performing RFC 5280-compliant certification path validation.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-261893	CD16-00-004000	SV-261893r1000684_rule		Medium

Description
The DOD standard for authentication is DOD-approved PKI certificates. A certificate's certification path is the path from the end entity certificate to a trusted root certification authority (CA). Certification path validation is necessary for a relying party to make an informed decision regarding acceptance of an end entity certificate. Certification path validation includes checks such as certificate issuer trust, time validity and revocation status for each certificate in the certification path. Revocation status information for CA and subject certificates in a certification path is commonly provided via certificate revocation lists (CRLs) or online certificate status protocol (OCSP) responses. Database Management Systems that do not validate certificates by performing RFC 5280-compliant certification path validation are in danger of accepting certificates that are invalid and/or counterfeit. This could allow unauthorized access to the database.

Description

The DOD standard for authentication is DOD-approved PKI certificates. A certificate's certification path is the path from the end entity certificate to a trusted root certification authority (CA). Certification path validation is necessary for a relying party to make an informed decision regarding acceptance of an end entity certificate. Certification path validation includes checks such as certificate issuer trust, time validity and revocation status for each certificate in the certification path. Revocation status information for CA and subject certificates in a certification path is commonly provided via certificate revocation lists (CRLs) or online certificate status protocol (OCSP) responses. Database Management Systems that do not validate certificates by performing RFC 5280-compliant certification path validation are in danger of accepting certificates that are invalid and/or counterfeit. This could allow unauthorized access to the database.

STIG	Date
Crunchy Data Postgres 16 Security Technical Implementation Guide	2024-06-17

Details

Check Text ( C-65747r1000682_chk )
Note: The following instructions use the PGDATA environment variable. Refer to APPENDIX-F for instructions on configuring PGDATA. To verify that a CRL file exists, as the database administrator (shown here as "postgres"), run the following: $ sudo su - postgres $ psql -c "SELECT CASE WHEN length(setting) > 0 THEN CASE WHEN substring(setting, 1, 1) = '/' THEN setting ELSE (SELECT setting FROM pg_settings WHERE name = 'data_directory') \|\| '/' \|\| setting END ELSE '' END AS ssl_crl_file FROM pg_settings WHERE name = 'ssl_crl_file';" If this is not set to a CRL file, this is a finding. Verify the existence of the CRL file by checking the directory from above: $ sudo su - postgres $ ls -ld If the CRL file does not exist, this is a finding. Verify that hostssl entries in pg_hba.conf have "cert" and "clientcert=verify-ca" enabled: $ sudo su - postgres $ grep '^hostssl.cert.clientcert=verify-ca ' ${PGDATA?}/pg_hba.conf If hostssl entries are not returned, this is a finding. If certificates are not being validated by performing RFC 5280-compliant certification path validation, this is a finding.

Check Text ( C-65747r1000682_chk )

Note: The following instructions use the PGDATA environment variable. Refer to APPENDIX-F for instructions on configuring PGDATA.

To verify that a CRL file exists, as the database administrator (shown here as "postgres"), run the following:

$ sudo su - postgres
$ psql -c "SELECT CASE WHEN length(setting) > 0
THEN CASE WHEN substring(setting, 1, 1) = '/'
THEN setting
ELSE (SELECT setting FROM pg_settings WHERE name = 'data_directory') || '/' || setting
END
ELSE ''
END AS ssl_crl_file
FROM pg_settings
WHERE name = 'ssl_crl_file';"

If this is not set to a CRL file, this is a finding.

Verify the existence of the CRL file by checking the directory from above:

$ sudo su - postgres
$ ls -ld

If the CRL file does not exist, this is a finding.

Verify that hostssl entries in pg_hba.conf have "cert" and "clientcert=verify-ca" enabled:

$ sudo su - postgres
$ grep '^hostssl.*cert.*clientcert=verify-ca ' ${PGDATA?}/pg_hba.conf

If hostssl entries are not returned, this is a finding.

If certificates are not being validated by performing RFC 5280-compliant certification path validation, this is a finding.

Fix Text (F-65655r1000683_fix)
Note: The following instructions use the PGDATA and PGVER environment variables. Refer to APPENDIX-F for instructions on configuring PGDATA and APPENDIX-H for PGVER. To configure PostgreSQL to use SSL, refer to supplementary content APPENDIX-G. To generate a Certificate Revocation List, refer to the official Red Hat Documentation: https://access.redhat.com/documentation/en-US/Red_Hat_Update_Infrastructure/2.1/html/Administration_Guide/chap-Red_Hat_Update_Infrastructure-Administration_Guide-Certification_Revocation_List_CRL.html. As the database administrator (shown here as "postgres"), copy the CRL file into the data directory: As the system administrator, copy the CRL file into the PostgreSQL Data Directory: $ sudo cp root.crl ${PGDATA?}/root.crl As the database administrator (shown here as "postgres"), set the ssl_crl_file parameter to the filename of the CRL: $ sudo su - postgres $ vi ${PGDATA?}/postgresql.conf ssl_crl_file = 'root.crl' In pg_hba.conf, require ssl authentication: $ sudo su - postgres $ vi ${PGDATA?}/pg_hba.conf hostssl cert clientcert=verify-ca As the system administrator, reload the server with the new configuration: # SYSTEMD SERVER ONLY $ sudo systemctl reload postgresql-${PGVER?}

Fix Text (F-65655r1000683_fix)

Note: The following instructions use the PGDATA and PGVER environment variables. Refer to APPENDIX-F for instructions on configuring PGDATA and APPENDIX-H for PGVER.

To configure PostgreSQL to use SSL, refer to supplementary content APPENDIX-G.

To generate a Certificate Revocation List, refer to the official Red Hat Documentation: https://access.redhat.com/documentation/en-US/Red_Hat_Update_Infrastructure/2.1/html/Administration_Guide/chap-Red_Hat_Update_Infrastructure-Administration_Guide-Certification_Revocation_List_CRL.html.

As the database administrator (shown here as "postgres"), copy the CRL file into the data directory:

As the system administrator, copy the CRL file into the PostgreSQL Data Directory:

$ sudo cp root.crl ${PGDATA?}/root.crl

As the database administrator (shown here as "postgres"), set the ssl_crl_file parameter to the filename of the CRL:

$ sudo su - postgres
$ vi ${PGDATA?}/postgresql.conf
ssl_crl_file = 'root.crl'

In pg_hba.conf, require ssl authentication:

$ sudo su - postgres
$ vi ${PGDATA?}/pg_hba.conf
hostssl

cert clientcert=verify-ca

As the system administrator, reload the server with the new configuration:

# SYSTEMD SERVER ONLY
$ sudo systemctl reload postgresql-${PGVER?}