Rule: EC2 Instances Should Not Have a Public IP Address
This rule emphasizes that EC2 instances should not be assigned a public IP address.
| Rule | EC2 instances should not have a public IP address |
| Framework | NIST 800-53 Revision 4 |
| Severity | ✔ High |
Rule Description:
This rule requires that EC2 instances should not have a public IP address in order to comply with NIST 800-53 Revision 4 security standards. A public IP address exposes the instance directly to the internet, increasing the risk of unauthorized access or attacks.
Troubleshooting Steps:
If an EC2 instance has a public IP address assigned, you can follow these troubleshooting steps:
- 1.
Identify the EC2 instance: Identify the instance ID of the EC2 instance that has a public IP address.
- 2.
Check security groups: Verify the security groups associated with the instance. Ensure that no inbound traffic rules allow access from any IP address or range (0.0.0.0/0) on ports that should not be publicly accessible.
- 3.
Check network ACLs: Review the network Access Control Lists (ACLs) associated with the VPC and the subnet in which the instance resides. Ensure that no inbound rules allow traffic from any IP address or range on ports that should not be publicly accessible.
- 4.
Verify VPC settings: Check the VPC settings to ensure that there are no configurations that allow public IP assignment to instances by default.
Remediation Steps:
To remediate the instance and remove the public IP address, follow these steps:
- 1.
Disassociate the Elastic IP: If an Elastic IP is associated with the instance, disassociate it. This will release the public IP address back to the pool.
- 2.
Modify the instance configuration: Modify the instance configuration by removing the public IP assignment. This can be done during instance launch or by modifying the instance attributes afterwards.
- 3.
Update security groups: Review and update the security groups associated with the instance. Remove any inbound rules that allow traffic from any IP address (0.0.0.0/0) on ports that should not be publicly accessible.
- 4.
Update network ACLs: If necessary, update the network ACLs associated with the VPC and the subnet to remove any inbound rules that allow traffic from any IP address or range on ports that should not be publicly accessible.
- 5.
Verify the instance: After applying the changes, verify that the instance no longer has a public IP address assigned. You can check the instance details in the AWS Management Console or use the AWS CLI command
to retrieve the instance information.describe-instances
CLI Command for Verification:
To verify if an EC2 instance has a public IP address assigned, you can use the following AWS CLI command:
aws ec2 describe-instances --instance-ids <instance-id> --query 'Reservations[].Instances[].PublicIpAddress'
Replace
<instance-id>Please note that you need to have the AWS CLI configured and authenticated with appropriate permissions to run this command.
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