1. Open the AWS Management Console and navigate to the EC2 service.
2. Select the EC2 instance that is allowing unrestricted SMTP access.
3. Click on the “Security” tab and scroll down to the “Security groups” section.
4. Click on the security group that is associated with the instance.
5. Click on the “Inbound rules” tab.
6. Locate the rule that allows SMTP traffic (port 25) with the source of “0.0.0.0/0” or ”::/0”.
7. Click on the “Edit” button next to the rule.
8. Change the source to a specific IP address range or security group that requires SMTP access.
9. Click the “Save” button to apply the changes.

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1. Open the AWS CLI on your local machine or EC2 instance.
2. Run the following command to list all the active SMTP settings in the AWS account:

aws ses get-account-sending-enabled

3. If the command output shows that the “SendingEnabled” parameter is set to “true”, then you need to disable it. Run the following command to disable SMTP access:

aws ses update-account-sending-enabled --no-sending-enabled

4. After running the above command, verify that the “SendingEnabled” parameter is set to “false” by running the following command:

aws ses get-account-sending-enabled

5. If the “SendingEnabled” parameter is set to “false”, then SMTP access has been successfully restricted in your AWS account.

1. Create a Python script to check for SMTP access:

import boto3

client = boto3.client('ec2')
response = client.describe_security_groups()

for group in response['SecurityGroups']:
    for permission in group['IpPermissions']:
        if permission.get('FromPort') == 25 and permission.get('IpRanges') == [{'CidrIp': '0.0.0.0/0'}]:
            group_id = group['GroupId']
            print(f"Found unrestricted SMTP access in security group {group_id}")

2. Once you have identified the security group(s) with unrestricted SMTP access, you can update the security group rules to restrict SMTP access to specific IP addresses or ranges.

import boto3

client = boto3.client('ec2')
response = client.authorize_security_group_ingress(
    GroupId='SECURITY_GROUP_ID',
    IpPermissions=[
        {
            'IpProtocol': 'tcp',
            'FromPort': 25,
            'ToPort': 25,
            'IpRanges': [
                {
                    'CidrIp': 'ALLOWED_IP_ADDRESS/32'
                }
            ]
        }
    ]
)

3. Run the Python script to check for and remediate unrestricted SMTP access in AWS.