PostgreSQL must generate audit records when privileges/permissions are added.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-72929	PGS9-00-004900	SV-87581r2_rule		Medium

Description
Changes in the permissions, privileges, and roles granted to users and roles must be tracked. Without an audit trail, unauthorized elevation or restriction of privileges could go undetected. Elevated privileges give users access to information and functionality that they should not have; restricted privileges wrongly deny access to authorized users. In an SQL environment, adding permissions is typically done via the GRANT command, or, in the negative, the REVOKE command.

Description

Changes in the permissions, privileges, and roles granted to users and roles must be tracked. Without an audit trail, unauthorized elevation or restriction of privileges could go undetected. Elevated privileges give users access to information and functionality that they should not have; restricted privileges wrongly deny access to authorized users. In an SQL environment, adding permissions is typically done via the GRANT command, or, in the negative, the REVOKE command.

STIG	Date
PostgreSQL 9.x Security Technical Implementation Guide	2017-12-27

Details

Check Text ( C-73063r1_chk )
Note: The following instructions use the PGDATA environment variable. See supplementary content APPENDIX-F for instructions on configuring PGDATA. First, as the database administrator (shown here as "postgres"), create a role by running the following SQL: Change the privileges of another user: $ sudo su - postgres $ psql -c "CREATE ROLE bob" Next, GRANT then REVOKE privileges from the role: $ psql -c "GRANT CONNECT ON DATABASE postgres TO bob" $ psql -c "REVOKE CONNECT ON DATABASE postgres FROM bob" postgres=# REVOKE CONNECT ON DATABASE postgres FROM bob; REVOKE postgres=# GRANT CONNECT ON DATABASE postgres TO bob; GRANT Now, as the database administrator (shown here as "postgres"), verify the events were logged: $ sudo su - postgres $ cat ${PGDATA?}/pg_log/ < 2016-07-13 16:25:21.103 EDT postgres postgres LOG: > AUDIT: SESSION,1,1,ROLE,GRANT,,,GRANT CONNECT ON DATABASE postgres TO bob, < 2016-07-13 16:25:25.520 EDT postgres postgres LOG: > AUDIT: SESSION,1,1,ROLE,REVOKE,,,REVOKE CONNECT ON DATABASE postgres FROM bob, If the above steps cannot verify that audit records are produced when privileges/permissions/role memberships are added, this is a finding.

Check Text ( C-73063r1_chk )

Note: The following instructions use the PGDATA environment variable. See supplementary content APPENDIX-F for instructions on configuring PGDATA.

First, as the database administrator (shown here as "postgres"), create a role by running the following SQL:

Change the privileges of another user:

$ sudo su - postgres
$ psql -c "CREATE ROLE bob"

Next, GRANT then REVOKE privileges from the role:

$ psql -c "GRANT CONNECT ON DATABASE postgres TO bob"
$ psql -c "REVOKE CONNECT ON DATABASE postgres FROM bob"

postgres=# REVOKE CONNECT ON DATABASE postgres FROM bob;
REVOKE

postgres=# GRANT CONNECT ON DATABASE postgres TO bob;
GRANT

Now, as the database administrator (shown here as "postgres"), verify the events were logged:

$ sudo su - postgres
$ cat ${PGDATA?}/pg_log/
< 2016-07-13 16:25:21.103 EDT postgres postgres LOG: > AUDIT: SESSION,1,1,ROLE,GRANT,,,GRANT CONNECT ON DATABASE postgres TO bob,
< 2016-07-13 16:25:25.520 EDT postgres postgres LOG: > AUDIT: SESSION,1,1,ROLE,REVOKE,,,REVOKE CONNECT ON DATABASE postgres FROM bob,

If the above steps cannot verify that audit records are produced when privileges/permissions/role memberships are added, this is a finding.

Fix Text (F-79373r2_fix)
Note: The following instructions use the PGDATA and PGVER environment variables. See supplementary content APPENDIX-F for instructions on configuring PGDATA and APPENDIX-H for PGVER. Using pgaudit PostgreSQL can be configured to audit these requests. See supplementary content APPENDIX-B for documentation on installing pgaudit. With pgaudit installed the following configurations can be made: $ sudo su - postgres $ vi ${PGDATA?}/postgresql.conf Add the following parameters (or edit existing parameters): pgaudit.log = 'role' Now, as the system administrator, reload the server with the new configuration: # SYSTEMD SERVER ONLY $ sudo systemctl reload postgresql-${PGVER?} # INITD SERVER ONLY $ sudo service postgresql-${PGVER?} reload

Fix Text (F-79373r2_fix)

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

Using pgaudit PostgreSQL can be configured to audit these requests. See supplementary content APPENDIX-B for documentation on installing pgaudit.

With pgaudit installed the following configurations can be made:

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

Add the following parameters (or edit existing parameters):

pgaudit.log = 'role'

Now, as the system administrator, reload the server with the new configuration:

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

# INITD SERVER ONLY
$ sudo service postgresql-${PGVER?} reload