Description: 

Security groups provide stateful filtering of ingress/egress network traffic to AWS resources. It is recommended that no security group allows unrestricted ingress access to Oracle ports 1521 or 2483. If restricted ingress access to Oracle ports means we do not allow to access my database.


Rationale: 

Removing unfettered connectivity to remote console services, and nobody will access my internal database server or Oracle, reduces a database server’s exposure to risk. 


Impact:

If we do not allow unrestricted ingress/inbound access to Oracle ports 1521 or 2483, it can minimize the opportunities for malicious activity such as hacking, data loss, and all multiple types of attacks( brute-force attacks, Denial of Service (DoS) attacks, etc).

For updating an existing environment, care should be taken to ensure that administrators currently relying on an existing ingress from 0.0.0.0/0 have access to Oracle ports 1521 or 2483 through another security group. 


Default Value: 

VPC automatically comes with a default security group. If you don't specify a different security group when you launch the instance, the default security group will be associated with the instance. By default, the security group allows all inbound connections. 


Pre-Requisite:

  1. Before starting, the below implementation steps write all configurations which IP and which port in the inbound.

  2. Avoid the login through the Root user.

  3. Only authorized persons (i.e, admins) can access the Security Groups.

  4. You cannot delete the default security groups but you can edit and modify them here so you can create security groups and create your own rules in them.

  5. Do not attach the default security group to any EC2 instance if you do not modify any default rules in inbound or outbound.


Remediation:


Test Plan: 

  1. Sign in to the AWS Management Console.

  2. Go to EC2 dashboard at https://console.aws.amazon.com/ec2/.

  3. Click on Security Groups, under the NETWORK & SECURITY section, in the left navigation pane 

  4. Select the Inbound tab 

  5. Verify the value in the Source column for any inbound rules with the Port Range set to 1521 have the source set to 0.0.0.0/0 or::/0 (Anywhere), then the selected security group allows unrestricted data traffic on port 1521.


Using AWS CLI:

The following command describes a security group the command you can use for each security groups individual to check which IP or ports are inbound or outbound:

aws ec2 describe-security-groups --group-ids <secuiryt_group_id>

Implementation Steps:

  1. Sign in to the AWS Management Console.
  2. Go to the EC2 dashboard at https://console.aws.amazon.com/ec2/.
  3. Click on Security Groups, under the NETWORK & SECURITY section, in the left navigation pane
  4. Select the appropriate security group (see Audit section to identify the right one(s)).
  5. Select the Inbound tab and click the Edit inbound rules button.
  6. In the Edit inbound rules dialog box, go-to source column and perform one of the following actions to restrict the inbound traffic: Click on the source dropdown
  7. Select My IP to allow inbound traffic only from your machine (i.e, from your IP address only).
  8. Select Custom and enter IP addresses or name or ID of another security group  based on your access requirement
  9. Click Save to apply the changes.


Using AWS CLI

List all security groups with an ingress rule of 0.0.0.0/0 

aws ec2 describe-security-groups --filters Name=ip-permission.cidr,Values='0.0.0.0/0' \
    --query "SecurityGroups[*].{Name:GroupName,ID:GroupId}"

Remove the rule 1521 or 2483 port used only e.g. you can revoke any port  

aws ec2 revoke-security-group-ingress \
  --group-id <value> --protocol <protocol> --port 1521 --cidr 0.0.0.0/0

 

Backout Plan:

If you want to proceed with previous settings go through the Implementation steps section and set all previous policies that you have written somewhere. Or else you can delete the security group you created

  1. Sign in to the AWS Management Console.
  2. Go to the EC2 dashboard at https://console.aws.amazon.com/ec2/.
  3. Click on Security Groups, under the NETWORK & SECURITY section, in the left navigation pane
  4. Open the security group by clicking on the security group ID 
  5. Click on Actions dropdown and select Delete Security groups

Using AWS CLI:

The following command is used to delete created security group id in the security_group_id enter the security group id which you show on your console.

aws ec2 delete-security-group --group-id <security_group_id>

Reference:

  1. revoke-security-group-ingress — AWS CLI 1.19.111 Command Reference

  2. get-instance-port-states — AWS CLI 1.19.111 Command Reference

  3. describe-security-groups — AWS CLI 1.19.107 Command Reference

  4. AWS::EC2::SecurityGroupIngress - AWS CloudFormation