PostgreSQL must generate audit records when security objects are deleted.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-72939	PGS9-00-005200	SV-87591r1_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
PostgreSQL 9.x Security Technical Implementation Guide	2017-01-20

Details

Check Text ( C-73069r1_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 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?}/pg_log/ 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-73069r1_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 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?}/pg_log/
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-79383r1_fix)
Note: The following instructions use the PGDATA environment variable. See supplementary content APPENDIX-F for instructions on configuring PGDATA. 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: # SYSTEMD SERVER ONLY $ sudo systemctl reload postgresql-9.5 # INITD SERVER ONLY $ sudo service postgresql-9.5 reload

Fix Text (F-79383r1_fix)

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

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:

# SYSTEMD SERVER ONLY
$ sudo systemctl reload postgresql-9.5

# INITD SERVER ONLY
$ sudo service postgresql-9.5 reload