PostgreSQL must enforce authorized access to all PKI private keys stored/utilized by PostgreSQL.

From PostgreSQL 9.x Security Technical Implementation Guide

Part of SRG-APP-000176-DB-000068

Associated with: CCI-000186

SV-87681r2_rule PostgreSQL must enforce authorized access to all PKI private keys stored/utilized by PostgreSQL.

Vulnerability discussion

The DoD standard for authentication is DoD-approved PKI certificates. PKI certificate-based authentication is performed by requiring the certificate holder to cryptographically prove possession of the corresponding private key.If the private key is stolen, an attacker can use the private key(s) to impersonate the certificate holder. In cases where PostgreSQL-stored private keys are used to authenticate PostgreSQL to the system’s clients, loss of the corresponding private keys would allow an attacker to successfully perform undetected man-in-the-middle attacks against PostgreSQL system and its clients.Both the holder of a digital certificate and the issuing authority must take careful measures to protect the corresponding private key. Private keys should always be generated and protected in FIPS 140-2 validated cryptographic modules.All access to the private key(s) of PostgreSQL must be restricted to authorized and authenticated users. If unauthorized users have access to one or more of PostgreSQL's private keys, an attacker could gain access to the key(s) and use them to impersonate the database on the network or otherwise perform unauthorized actions.

Check content

First, as the database administrator (shown here as "postgres"), verify the following settings: Note: If no specific directory given before the filename, the files are stored in PGDATA. $ sudo su - postgres $ psql -c "SHOW ssl_ca_file" $ psql -c "SHOW ssl_cert_file" $ psql -c "SHOW ssl_crl_file" $ psql -c "SHOW ssl_key_file" If the directory these files are stored in is not protected, this is a finding.

Fix text

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. Store all PostgreSQL PKI private keys in a FIPS 140-2-validated cryptographic module. Ensure access to PostgreSQL PKI private keys is restricted to only authenticated and authorized users.  PostgreSQL private key(s) can be stored in $PGDATA directory, which is only accessible by the database owner (usually postgres, DBA) user. Do not allow access to this system account to unauthorized users.  To put the keys in a different directory, as the database administrator (shown here as "postgres"), set the following settings to a protected directory:  $ sudo su - postgres  $ vi ${PGDATA?}/postgresql.conf  ssl_ca_file = "/some/protected/directory/root.crt"  ssl_crl_file = "/some/protected/directory/root.crl"  ssl_cert_file = "/some/protected/directory/server.crt"  ssl_key_file = "/some/protected/directory/server.key"  Now, as the system administrator, restart the server with the new configuration:  # SYSTEMD SERVER ONLY  $ sudo systemctl restart postgresql-${PGVER?} # INITD SERVER ONLY  $ sudo service postgresql-${PGVER?} restart  For more information on configuring PostgreSQL to use SSL, see supplementary content APPENDIX-G.

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