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V-233556

CAT II (Medium)

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

Rule ID

SV-233556r961800_rule

STIG

Crunchy Data PostgreSQL Security Technical Implementation Guide

Version

V3R1

CCIs

CCI-000172

Discussion

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 a SQL environment, adding permissions is typically done via the GRANT command, or, in the negative, the REVOKE command.

Check Content

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

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

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

$ sudo su - postgres
$ cat ${PGDATA?}/${PGLOG?}/<latest_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,<none>
< 2016-07-13 16:25:25.520 EDT postgres postgres LOG: > AUDIT: SESSION,1,1,ROLE,REVOKE,,,REVOKE CONNECT ON DATABASE postgres FROM bob,<none>

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

Fix Text

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:

$ sudo systemctl reload postgresql-${PGVER?}