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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-87591r2_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 2018-02-27

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.
Fix Text (F-79383r2_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: 

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

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