# Ensure no security groups allow ingress from 0.0.0.0/0 or ::/0 to port 3389.

- Source: https://support.icompaas.com/support/solutions/articles/62000236316-ensure-no-security-groups-allow-ingress-from-0-0-0-0-0-or-0-to-port-3389-
- Section: [Solutions](https://support.icompaas.com/support/solutions) › [AWS Checks New Version](https://support.icompaas.com/support/solutions/62000112673) › [AWS New Checks](https://support.icompaas.com/support/solutions/folders/62000169206)
- Last updated: 2026-05-29
- Publisher: iCompaas, Inc. (https://www.icompaas.com)

### Profile Applicability:

-   Level 1
    

### Description:

This control ensures that AWS Security Groups do not allow unrestricted inbound traffic (0.0.0.0/0 for IPv4 or ::/0 for IPv6) to TCP port 3389, which is used for Microsoft Remote Desktop Protocol (RDP) access. Allowing open access to RDP significantly increases the risk of brute-force attacks, unauthorized system access, and exploitation of known Windows vulnerabilities. Restricting RDP access to trusted IP addresses or through secure gateways (like a Bastion Host or VPN) mitigates these risks. 

### Rationale:

RDP is a common attack vector for threat actors attempting to gain unauthorized access to Windows-based systems. If port 3389 is exposed to the internet, attackers can perform automated scans to identify open ports and execute brute-force or credential-stuffing attacks. Restricting access to RDP by limiting the source IP range or using a private connection (e.g., AWS Systems Manager Session Manager, VPN, or AWS Direct Connect) ensures adherence to the principle of least privilege and protects internal infrastructure from external threats. 

### Impact:

-   Positive Impact: Enhances the security posture by reducing the exposure of Windows-based EC2 instances to external attacks and ensuring access is granted only through secure and controlled channels.
    
-   Negative Impact: May limit direct RDP access for legitimate users unless a secure alternative (such as VPN or Bastion Host) is implemented. 
    

### Default Value:

By default, new AWS Security Groups have no inbound rules, meaning RDP access must be explicitly allowed. 

### Pre-Requisite:

-   IAM permissions required: ec2:DescribeSecurityGroups, ec2:RevokeSecurityGroupIngress, ec2:AuthorizeSecurityGroupIngress.
-   Identify approved IP ranges or networks that legitimately require RDP access.

### Remediation:

### Test Plan 

### Using AWS Console:

1.  Sign in to the AWS Management Console.
    
2.  Navigate to EC2 → Security Groups.
    
3.  Select each Security Group and open the Inbound Rules tab.
    
4.  Check for rules with:
    
    -   Protocol: TCP
        
    -   Port Range: 3389
        
    -   Source: 0.0.0.0/0 or ::/0
        
5.  If any rule matches this configuration, the Security Group is non-compliant.
    

### Implementation Plan 

### Using AWS Console:

1.  Navigate to EC2 → Security Groups.
    
2.  Select the non-compliant Security Group.
    
3.  Click Edit inbound rules.
    
4.  Identify and delete any rule that allows TCP 3389 from 0.0.0.0/0 or ::/0.
    
5.  Add new inbound rules to restrict RDP access:
    
    -   Source: Authorized corporate or VPN CIDR blocks (e.g., 10.0.0.0/16).
        
    -   Source: Specific admin IP addresses (e.g., 203.0.113.25/32).
        
6.  Click Save rules to apply changes.
    
7.  Test connectivity to ensure legitimate RDP users can still connect securely.
    

### Backout Plan:

### Using AWS Console:

1.  If access issues occur after restricting rules, temporarily re-add a specific trusted IP range to restore administrative access.
2.  Implement a secure access solution such as AWS Systems Manager Session Manager, Bastion Host, or VPN to manage RDP connections securely.

### References:

-   Amazon EC2 Security Groups Documentation
-   AWS Well-Architected Framework – Security Pillar
-   AWS Security Best Practices Whitepaper

## Related compliance guidance

- [SOC 2 compliance: a practical implementation guide for cloud-native SaaS teams](https://support.icompaas.com/compliance/soc-2-trust-services-criteria): Configuration checks like this one are the technical half of a SOC 2 / ISO 27001 programme — the guide shows where they fit, what else an auditor expects, and how to evidence them.
- [ISO/IEC 27001:2022 compliance: a practical implementation guide](https://support.icompaas.com/compliance/iso-27001-2022): ISO 27001 Annex A.8 (technological controls) is where cloud hardening evidence lands; the guide shows how to run the ISMS around it.