PostgreSQL must generate audit records when security objects are deleted.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-233559	CD12-00-005200	SV-233559r617333_rule		Medium

Description
The removal of security objects from the database/PostgreSQL would seriously degrade a system's information assurance posture. If such an event occurs, it must be logged.

STIG	Date
Crunchy Data PostgreSQL Security Technical Implementation Guide	2020-12-11

Details

Check Text ( C-36753r606900_chk )
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 test table stig_test, enable row level security, and create a policy by running the following SQL: $ sudo su - postgres $ psql -c "CREATE TABLE stig_test(id INT)" $ psql -c "ALTER TABLE stig_test ENABLE ROW LEVEL SECURITY" $ psql -c "CREATE POLICY lock_table ON stig_test USING ('postgres' = current_user)" Next, drop the policy and disable row level security: $ psql -c "DROP POLICY lock_table ON stig_test" $ psql -c "ALTER TABLE stig_test DISABLE ROW LEVEL SECURITY" Now, as the database administrator (shown here as "postgres"), verify the security objects deletions were logged: $ cat ${PGDATA?}/${PGLOG?}/ 2016-03-30 14:54:18.991 EDT postgres postgres LOG: AUDIT: SESSION,11,1,DDL,DROP POLICY,,,DROP POLICY lock_table ON stig_test;, 2016-03-30 14:54:42.373 EDT postgres postgres LOG: AUDIT: SESSION,12,1,DDL,ALTER TABLE,,,ALTER TABLE stig_test DISABLE ROW LEVEL SECURITY;, If audit records are not produced when security objects are dropped, this is a finding.

Check Text ( C-36753r606900_chk )

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 test table stig_test, enable row level security, and create a policy by running the following SQL:

$ sudo su - postgres
$ psql -c "CREATE TABLE stig_test(id INT)"
$ psql -c "ALTER TABLE stig_test ENABLE ROW LEVEL SECURITY"
$ psql -c "CREATE POLICY lock_table ON stig_test USING ('postgres' = current_user)"

Next, drop the policy and disable row level security:

$ psql -c "DROP POLICY lock_table ON stig_test"
$ psql -c "ALTER TABLE stig_test DISABLE ROW LEVEL SECURITY"

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

$ cat ${PGDATA?}/${PGLOG?}/
2016-03-30 14:54:18.991 EDT postgres postgres LOG: AUDIT: SESSION,11,1,DDL,DROP POLICY,,,DROP POLICY lock_table ON stig_test;,
2016-03-30 14:54:42.373 EDT postgres postgres LOG: AUDIT: SESSION,12,1,DDL,ALTER TABLE,,,ALTER TABLE stig_test DISABLE ROW LEVEL SECURITY;,

If audit records are not produced when security objects are dropped, this is a finding.

Fix Text (F-36718r606901_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 = 'ddl' Now, as the system administrator, reload the server with the new configuration: $ sudo systemctl reload postgresql-${PGVER?}

Fix Text (F-36718r606901_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 = 'ddl'

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

$ sudo systemctl reload postgresql-${PGVER?}