Small and medium-sized businesses (SMBs) increasingly rely on remote access solutions to manage systems, support employees, and maintain operations. Among the most commonly used tools is Microsoft’s Remote Desktop Protocol (RDP), which uses port 3389 to enable remote connections to Windows computers and servers. While it offers cost-effective convenience, port 3389 can also expose SMBs to major cybersecurity risks if left unprotected.
Understanding the importance and risks of port 3389 is essential for any business seeking to balance operational efficiency with cybersecurity best practices.
What Is Port 3389 and Why Do SMBs Use It?
Port 3389 is the default TCP port used by RDP, a feature built into Microsoft Windows that allows users to connect to another PC remotely with a graphical interface. It is used extensively by IT staff for remote support, by employees working from home, and by contractors managing off-site infrastructure.
For SMBs, the use of RDP over port 3389 is attractive because:
- It comes built into Windows, reducing the need for expensive third-party tools.
- It allows real-time remote troubleshooting.
- It supports flexible work environments.
- It enables centralized IT control over distributed systems.
These benefits make RDP over port 3389 particularly valuable for smaller organizations that lack the budget or staff for more complex remote access solutions.
The Security Challenge of Port 3389
Despite its utility, port 3389 is one of the most targeted ports on the internet. Cybercriminals are constantly scanning for open RDP ports as they represent a straightforward path into corporate networks.
Common attack methods include:
- Brute-force attacks where hackers try thousands of password combinations.
- Credential stuffing using leaked passwords from data breaches.
- Exploitation of unpatched RDP vulnerabilities.
- Remote deployment of ransomware, which can cripple SMBs that don’t have strong backup and recovery processes.
These types of attacks are particularly devastating for SMBs that may lack advanced threat detection or a full-time cybersecurity team.
Real-World SMB Risks
Statistics from cybersecurity firms show that many ransomware attacks on small businesses start with an exposed port 3389. Once access is gained, attackers can steal data, lock down systems, or demand ransoms—often with catastrophic results. Unlike large corporations, SMBs may not recover quickly or at all after such an incident.
Therefore, protecting port 3389 is not optional—it’s critical.
Best Practices for SMBs to Secure Port 3389
Here are practical and affordable steps small businesses can take to secure RDP access through port 3389:
- Disable RDP If Not Needed
If your business doesn’t require RDP, turn it off completely. - Restrict RDP Access with a Firewall
Only allow access to port 3389 from specific IP addresses or internal VPN connections. - Use Strong Passwords and Account Lockout Policies
Enforce long, complex passwords and automatically lock accounts after multiple failed attempts. - Enable Network Level Authentication (NLA)
This forces users to authenticate before a session is established, adding an extra layer of protection. - Use a VPN
Instead of exposing port 3389 directly to the internet, place RDP behind a VPN. This keeps the port closed to outside access. - Keep Systems Updated
Always apply the latest Windows patches, especially for known RDP vulnerabilities. - Consider Using a Remote Desktop Gateway
A gateway adds a secure layer between external connections and internal systems. - Monitor RDP Logs
Check Windows Event Viewer or use a third-party log management system to track login attempts and connection history. - Use Two-Factor Authentication (2FA)
Adding 2FA to RDP sessions can prevent unauthorized access, even if passwords are compromised.
Should SMBs Change the Port from 3389?
Changing the default RDP port from 3389 to a non-standard port is sometimes suggested as a security measure. This can reduce automated scans but won’t stop determined attackers. It should be considered a supplementary tactic, not a substitute for proper security configuration.
Conclusion
For SMBs, the ability to connect to systems remotely through RDP and port 3389 can streamline operations and reduce costs. However, this convenience comes with real security threats that must be addressed. By taking proactive steps—many of which are free or low-cost—businesses can continue to use RDP safely without putting themselves at risk.
In the digital age, cybersecurity is a responsibility, not just an IT issue. And for small businesses, securing port 3389 may be the most important first step toward building a stronger security foundation.