RDS IAM Auth + SSO Users

Question

Hi all,

I have 2 accounts:
- Mgmt (SSO enabled)
- Development (RDS)

I have **SSO** configured with a group (team_leaders) and permission set (TeamLeaderAccess).

Are part of this group:
- john
- michael

I've configured a RDS DB (Postgre) with IAM Auth and created these users into the database.

Now I'm trying to configure the **Permission Set** with this policy:
```
{
    "Action": "rds-db:connect",
    "Effect": "Allow",
    "Resource": "arn:aws:rds-db:us-east-1::dbuser:db-KF.../*"
}
```

In this case, John is able to get his SSO credentials and log-in into RDS **as john AND michael** (impersonation), because I have this "/*" in my policy.

On the other hand, if I replace that by:
```
{
    "Action": "rds-db:connect",
    "Effect": "Allow",
    "Resource": "arn:aws:rds-db:us-east-1::dbuser:db-KF.../john"
}
```
Michael won't be able to log in.

How to setup a policy per user?

Has anyone faced this scenario and found a solution for it?

Thanks,

Accepted Answer

It's possible to simplify the management of AWS RDS access while leveraging AWS Single Sign-On (SSO) using dynamic IAM policies. Here's a quick guide:
    
1. **Goal**: Enable secure, user-specific access to AWS RDS databases, preventing impersonation.
2. **Strategy**: Utilize AWS SSO with dynamic IAM policies, incorporating the `${aws:username}` variable to align SSO usernames with database usernames.

**Implementation:**

1. **Activate AWS SSO ABAC**: Allows for dynamic permissions based on user context. 
2. **Configure a Dynamic IAM Policy**: Insert ${aws:username} in the policy to ensure users can only access their database user.

```
{
    "Action": "rds-db:connect",
    "Effect": "Allow",
    "Resource": "arn:aws:rds-db:us-east-1::dbuser:db-KF.../${aws:username}"
}
```

> **Note**: Ensure Consistency between SSO usernames and RDS database usernames. This alignment is critical for the dynamic policy to function correctly.

Additionally, you have the option to conduct tests by utilizing the IAM Policy Simulator, which allows for the simulation of permissions and actions for each user within the group. For more detailed analysis, you can access the tool directly at https://policysim.aws.amazon.com/home/index.jsp.

![Using the policy to validate users](/media/postImages/original/IM7bzwiAYxSPiLHmPsVKfjLg)

Resources:
1. https://docs.aws.amazon.com/singlesignon/latest/userguide/attributesforaccesscontrol.html

RDS IAM Auth + SSO Users

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