control "V-73005" do

  title "PostgreSQL must produce audit records containing sufficient information to
establish the sources (origins) of the events."
  desc  "Information system auditing capability is critical for accurate forensic
analysis. Without establishing the source of the event, it is impossible to
establish, correlate, and investigate the events relating to an incident.

In order to compile an accurate risk assessment and provide forensic analysis, it is
essential for security personnel to know where events occurred, such as application
components, modules, session identifiers, filenames, host names, and functionality.

In addition to logging where events occur within the application, the application
must also produce audit records that identify the application itself as the source
of the event.

Associating information about the source of the event within the application
provides a means of investigating an attack; recognizing resource utilization or
capacity thresholds; or identifying an improperly configured application."

  impact 0.5
  tag "severity": "medium"
  tag "gtitle": "SRG-APP-000098-DB-000042"
  tag "gid": "V-73005"
  tag "rid": "SV-87657r1_rule"
  tag "stig_id": "PGS9-00-008800"
  tag "cci": "CCI-000133"
  tag "nist": ["AU-3", "Rev_4"]

  tag "check": "Check PostgreSQL settings and existing audit records to verify
information specific to the source (origin) of the event is being captured and
stored with audit records.

As the database administrator (usually postgres, check the current log_line_prefix
and \"log_hostname\" setting by running the following SQL:

$ sudo su - postgres
$ psql -c \"SHOW log_line_prefix\"
$ psql -c \"SHOW log_hostname\"

For a complete list of extra information that can be added to log_line_prefix, see
the official documentation:
https://www.postgresql.org/docs/current/static/runtime-config-logging.html#GUC-LOG-LI
NE-PREFIX

If the current settings do not provide enough information regarding the source of
the event, 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.

To ensure that logging is enabled, review supplementary content APPENDIX-C for
instructions on enabling logging.

If logging is enabled the following configurations can be made to log the source of
an event.

First, as the database administrator, edit postgresql.conf:

$ sudo su - postgres
$ vi ${PGDATA?}/postgresql.conf

###### Log Line Prefix

Extra parameters can be added to the setting log_line_prefix to log source of event:

# %a = application name
# %u = user name
# %d = database name
# %r = remote host and port
# %p = process ID
# %m = timestamp with milliseconds

For example:
log_line_prefix = '< %m %a %u %d %r %p %m >'

###### Log Hostname

By default only IP address is logged. To also log the hostname the following
parameter can also be set in postgresql.conf:

log_hostname = on

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 log_line_prefix;', [PG_DB]) do
    its('output') { should eq PG_LOG_LINE_PREFIX.strip }
  end

  describe sql.query('SHOW log_hostname;', [PG_DB]) do
    its('output') { should match /on|true/i }
  end
end