Why You Should Avoid Using Port 3389 for Remote Desktop

Port 3389 is one of the most scanned, targeted, and exploited ports on the internet. If you’re using Microsoft’s Remote Desktop Protocol (RDP) without locking it down, you might be giving attackers exactly what they’re looking for: a direct path into your network.

What is port 3389 used for? It’s the default port RDP relies on to let users remotely access Windows machines. While convenient, that default setting comes with a serious tradeoff: predictability. Cybercriminals know what it is, where to look, and how to exploit it.

Because of this, securing remote access—without sacrificing functionality—is a must. Here’s what you need to know.

Risks of Using Port 3389

Leaving port 3389 open to the internet is like leaving your front door unlocked. In fact, according to Shodan, millions of devices are still exposing RDP over port 3389 to the public internet, many of them running outdated software with known vulnerabilities.

That’s a huge problem. Here’s why:

1. Brute Force Attacks

Attackers routinely scan for open RDP ports, especially port 3389, and launch automated brute force attacks to guess login credentials. Unfortunately, those attacks don’t need to be sophisticated—just persistent. If your system uses weak passwords or lacks account lockout policies, an attacker could gain access in minutes.

2. Known for RDP Vulnerabilities

The RDP protocol has a long history of critical security flaws. One of the most infamous—BlueKeep (CVE-2019-0708)—allowed attackers to execute code remotely on unpatched systems. While that specific vulnerability has since been patched, new ones continue to emerge. If you expose TCP port 3389 to the internet and haven’t patched aggressively, your system is a sitting duck for exploit kits and zero-day threats.

3. Credential Stuffing & Password Attacks

Attackers don’t always guess passwords from scratch. Instead, they often use stolen credentials from past data breaches. This method, called credential stuffing, is particularly effective when employees reuse passwords across platforms. Exposed RDP ports provide a direct gateway for attackers to test those stolen credentials against your network.

4. Unencrypted Traffic

Unless properly secured, RDP traffic can be transmitted in plaintext over port 3389, leaving it vulnerable to man-in-the-middle (MITM) attacks. If intercepted, attackers can capture login credentials, screen content, and other sensitive data. Without layered encryption or VPN tunneling, you’re sending critical information over the digital equivalent of an open radio channel.

5. Internet Exposure Increases Your Attack Surface

Directly exposing remote desktop port 3389 to the internet dramatically increases your attack surface. This means more entry points, more scanning activity, and more chances for something to go wrong. In most cases, there’s no valid reason to allow direct access to RDP from the public internet.

Best Practices to Secure Remote Desktop Access

So, how can you protect your organization without sacrificing remote access? The good news is that you don’t have to abandon RDP entirely. You just need to use it more securely. Here’s how you can reduce your risk:

Change the Default RDP Port

Changing port 3389 to a non-standard port won’t stop targeted attacks, but it can reduce noise from automated scans. This is a good first step, not a full solution. Ideally, you should use this in conjunction with firewall rules, VPNs, and access controls.

Use a VPN or Remote Access Gateway

Instead of exposing RDP to the internet, tunnel it through a VPN or Remote Desktop Gateway. These tools restrict access to trusted users and encrypt traffic end-to-end. This single change can substantially reduce your vulnerability and help satisfy security compliance requirements.

Require a Multi-Factor Authentication (MFA)

Enable MFA for all users with remote access privileges. Even if an attacker steals a password, MFA stops them from logging in without a second authentication factor, such as a push notification or token. This is one of the most effective defenses against credential-based attacks.

Enforce Strong Passwords and Account Lockouts

Set password policies that require complexity and regular updates. Combine this with account lockout policies after repeated failed login attempts to block brute force activity. Additionally, implement role-based access controls to ensure users only have access to what they need.

Regularly Patch and Monitor

Always apply the latest security updates to systems running RDP. Enable centralized logging, use endpoint detection tools, and review access logs regularly for signs of suspicious activity. Staying current with patches is your best defense against new port 3389 vulnerabilities.

Don’t Let Port 3389 Be Your Weakest Link

RDP is a powerful tool. But exposing port 3389 without proper protections is one of the most common—and expensive—security mistakes businesses make.

The solution isn’t to ditch remote desktop access entirely, though. It’s to layer it with the right protections: encryption, VPNs, multi-factor authentication, and ongoing monitoring.

That’s where we come in. At Safepoint IT, we offer managed IT services designed to help you build secure, scalable systems that keep your business running smoothly without opening the door to cyberattacks. Contact us today to learn more about how we can help your organization.