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Amazon Aurora
User Guide for Aurora (API Version 2014-10-31)

AWS Documentation » Amazon Relational Database Service (RDS) » User Guide for Aurora » Working with Amazon Aurora PostgreSQL » Security with Amazon Aurora PostgreSQL
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Security with Amazon Aurora PostgreSQL

Security for Amazon Aurora PostgreSQL is managed at three levels:

  • To control who can perform Amazon RDS management actions on Aurora DB clusters and DB instances, you use AWS Identity and Access Management (IAM). When you connect to AWS using IAM credentials, your IAM account must have IAM policies that grant the permissions required to perform Amazon RDS management operations. For more information, see Identity and Access Management in Amazon Aurora.

    If you are using an IAM account to access the Amazon RDS console, you must first log on to the AWS Management Console with your IAM account, and then go to the Amazon RDS console at https://console.aws.amazon.com/rds.

  • Aurora DB clusters must be created in an Amazon Virtual Private Cloud (VPC). To control which devices and Amazon EC2 instances can open connections to the endpoint and port of the DB instance for Aurora DB clusters in a VPC, you use a VPC security group. These endpoint and port connections can be made using Secure Sockets Layer (SSL). In addition, firewall rules at your company can control whether devices running at your company can open connections to a DB instance. For more information on VPCs, see Amazon Virtual Private Cloud VPCs and Amazon Aurora.

    Aurora PostgreSQL supports db.r4 and db.t3 instance classes with default VPC only. With default VPC tenancy, the VPC runs on shared hardware. With dedicated VPC tenancy, the VPC runs on a dedicated hardware instance. For more information about instance classes, see Choosing the DB Instance Class. For more information about default and dedicated VPC tenancy, see Dedicated Instances in the Amazon EC2 User Guide for Linux Instances.

  • To authenticate login and permissions for an Amazon Aurora DB cluster, you can take the same approach as with a stand-alone instance of PostgreSQL.

    Commands such as CREATE ROLE, ALTER ROLE, GRANT, and REVOKE work just as they do in on-premises databases, as does directly modifying database schema tables. For more information, see Client Authentication in the PostgreSQL documentation.

    Note

    The Salted Challenge Response Authentication Mechanism (SCRAM) is not supported with Aurora PostgreSQL.

When you create an Amazon Aurora PostgreSQL DB instance, the master user has the following default privileges:

  • LOGIN

  • NOSUPERUSER

  • INHERIT

  • CREATEDB

  • CREATEROLE

  • NOREPLICATION

  • VALID UNTIL 'infinity'

To provide management services for each DB cluster, the rdsadmin user is created when the DB cluster is created. Attempting to drop, rename, change the password, or change privileges for the rdsadmin account will result in an error.

Restricting Password Management

You can restrict who can manage database user passwords to a special role. By doing this, you can have more control over password management on the client side.

You enable restricted password management with the static parameter rds.restrict_password_commands and use a role called rds_password. When the parameter rds.restrict_password_commands is set to 1, only users that are members of the rds_password role can run certain SQL commands. The restricted SQL commands are commands that modify database user passwords and password expiration time.

To use restricted password management, your DB cluster must be running Amazon Aurora for PostgreSQL 10.6 or higher. Because the rds.restrict_password_commands parameter is static, changing this parameter requires a database restart.

When a database has restricted password management enabled, if you try to run restricted SQL commands you get the following error: ERROR: must be a member of rds_password to alter passwords.

Following are some examples of SQL commands that are restricted when restricted password management is enabled. 

postgres=> CREATE ROLE myrole WITH PASSWORD 'mypassword';
postgres=> CREATE ROLE myrole WITH PASSWORD 'mypassword' VALID UNTIL '2020-01-01';
postgres=> ALTER ROLE myrole WITH PASSWORD 'mypassword' VALID UNTIL '2020-01-01';
postgres=> ALTER ROLE myrole WITH PASSWORD 'mypassword';
postgres=> ALTER ROLE myrole VALID UNTIL '2020-01-01';
postgres=> ALTER ROLE myrole RENAME TO myrole2;

Some ALTER ROLE commands that include RENAME TO might also be restricted. They might be restricted because renaming a PostgreSQL role that has an MD5 password clears the password.

The rds_superuser role has membership for the rds_password role by default, and you can't change this. You can give other roles membership for the rds_password role by using the GRANT SQL command. We recommend that you give membership to rds_password to only a few roles that you use solely for password management. These roles require the CREATEROLE attribute to modify other roles.

Make sure that you verify password requirements such as expiration and needed complexity on the client side. We recommend that you restrict password-related changes by using your own client-side utility. This utility should have a role that is a member of rds_password and has the CREATEROLE role attribute.