V-73003

control "V-73003" do
  title "PostgreSQL must implement cryptographic mechanisms to prevent unauthorized
modification of organization-defined information at rest (to include, at a minimum,
PII and classified information) on organization-defined information system
components."
  desc  "PostgreSQLs handling data requiring \"data at rest\" protections must
employ cryptographic mechanisms to prevent unauthorized disclosure and modification
of the information at rest. These cryptographic mechanisms may be native to
PostgreSQL or implemented via additional software or operating system/file system
settings, as appropriate to the situation.

Selection of a cryptographic mechanism is based on the need to protect the integrity
of organizational information. The strength of the mechanism is commensurate with
the security category and/or classification of the information. Organizations have
the flexibility to either encrypt all information on storage devices (i.e., full
disk encryption) or encrypt specific data structures (e.g., files, records, or
fields).

The decision whether and what to encrypt rests with the data owner and is also
influenced by the physical measures taken to secure the equipment and media on which
the information resides."
  impact 0.5
  tag "severity": "medium"
  tag "gtitle": "SRG-APP-000428-DB-000386"
  tag "gid": "V-73003"
  tag "rid": "SV-87655r1_rule"
  tag "stig_id": "PGS9-00-008700"
  tag "cci": "CCI-002475"
  tag "nist": ["SC-28 (1)", "Rev_4"]

  tag "check": "Review the system documentation to determine whether the
organization has defined the information at rest that is to be protected from
modification, which must include, at a minimum, PII and classified information.

If no information is identified as requiring such protection, this is not a finding.

Review the configuration of PostgreSQL, operating system/file system, and additional
software as relevant.

If any of the information defined as requiring cryptographic protection from
modification is not encrypted in a manner that provides the required level of
protection, this is a finding.

One possible way to encrypt data within PostgreSQL is to use pgcrypto extension.

To check if pgcrypto is installed on PostgreSQL, as a database administrator (shown
here as \"postgres\"), run the following command:

$ sudo su - postgres
$ psql -c \"SELECT * FROM pg_available_extensions where name='pgcrypto'\"

If data in the database requires encryption and pgcrypto is not available, this is a
finding.

If disk or filesystem requires encryption, ask the system owner, DBA, and SA to
demonstrate filesystem or disk level encryption.

If this is required and is not found, this is a finding."
  tag "fix": "Configure PostgreSQL, operating system/file system, and additional
software as relevant, to provide the required level of cryptographic protection.

The pgcrypto module provides cryptographic functions for PostgreSQL. See
supplementary content APPENDIX-E for documentation on installing pgcrypto.

With pgcrypto installed, it's possible to insert encrypted data into the database:

INSERT INTO accounts(username, password) VALUES ('bob', crypt('a_secure_password',
gen_salt('md5')));"

  sql = postgres_session(PG_DBA, PG_DBA_PASSWORD, PG_HOST)

  pgcrypto_sql = "SELECT * FROM pg_available_extensions where name='pgcrypto'"

  describe sql.query(pgcrypto_sql, [PG_DB]) do
    its('output') { should_not eq '' }
  end
end