V-72959

control "V-72959" do
  title "PostgreSQL must generate audit records when privileges/permissions are
  deleted."
  desc  "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, deleting permissions is typically done via the REVOKE
  command."
  impact 0.5
  tag "severity": "medium"
  tag "gtitle": "SRG-APP-000499-DB-000330"
  tag "gid": "V-72959"
  tag "rid": "SV-87611r1_rule"
  tag "stig_id": "PGS9-00-006100"
  tag "cci": "CCI-000172"
  tag "nist": ["AU-12 c", "Rev_4"]
  tag "check": "First, as the database administrator, verify pgaudit is enabled
  by running the following SQL:
  $ sudo su - postgres
  $ psql -c \"SHOW shared_preload_libraries\"
  If the output does not contain pgaudit, this is a finding.
  Next, verify that role, read, write, and ddl auditing are enabled:
  $ psql -c \"SHOW pgaudit.log\"
  If the output does not contain role, read, write, and ddl, this is a finding."
  tag "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 = 'role'
  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"

  sql = postgres_session(PG_DBA, PG_DBA_PASSWORD, PG_HOST)

  describe sql.query('SHOW shared_preload_libraries;', [PG_DB]) do
    its('output') { should include 'pgaudit' }
  end

  pgaudit_types = %w(ddl read role write)

  pgaudit_types.each do |type|
    describe sql.query('SHOW pgaudit.log;', [PG_DB]) do
      its('output') { should include type }
    end
  end
end