Remote Desktop Protocol (RDP) is a secure network communications protocol developed by Microsoft. It allows a user to connect to and control another computer over a network connection, creating a remote desktop experience.
TL;DR: RDP lets you use another computer from afar, as if you were sitting right in front of it. While super useful for IT support and remote work, it's also a prime target for threat actors if not properly secured. Think of it as a remote-controlled car for computers—you're the driver, but you need to make sure no one else can hijack the signal.
How does remote desktop protocol work?
So, you want to control your work computer from your couch? That's where RDP comes in. It operates on a client-server model. The computer you want to control (the "server") runs RDP server software, and the device you're using to control it (the "client") runs RDP client software.
When you start a session, your client device sends a request to the server over a network—usually the internet. Once you're authenticated (proving you are who you say you are), the server sends back a stream of its graphical user interface (GUI). Every mouse click, keyboard stroke, and window you open on your client device is transmitted to the server, which executes the commands and sends the visual updates back to you.
This whole exchange typically happens over TCP/IP port 3389. Remember that port number; it’s a favorite for attackers scanning for vulnerable systems. The data is encrypted to protect it from prying eyes, but the strength of that protection depends on how RDP is configured.
Why do threat actors love RDP?
RDP is a powerful tool for legitimate users, which makes it an equally powerful tool for cybercriminals. It’s one of the most common attack vectors because a successful RDP compromise gives an attacker direct, hands-on keyboard access to a target machine. It’s like handing them the keys to the kingdom.
Here’s why it’s such a juicy target:
Weak Credentials: People often use simple, easy-to-guess passwords like "Password123!" or reuse them across multiple services. Attackers use brute-force attacks—automated tools that try thousands of password combinations per second—to crack these weak credentials and gain access.
Exposed Ports: Many businesses expose RDP directly to the internet without any extra security layers. By leaving port 3389 open, they're basically putting up a giant "Welcome, Hackers!" sign. Attackers constantly scan the web for open RDP ports.
Unpatched Vulnerabilities: Like any software, RDP has had its share of vulnerabilities over the years (think BlueKeep). If systems aren't patched regularly, they remain susceptible to exploits that can grant an attacker access without even needing credentials. Once they’re in, they can deploy ransomware, steal data, or use the compromised machine to attack other systems on the network.
According to the Cybersecurity and Infrastructure Security Agency (CISA), malicious cyber actors often exploit RDP to launch ransomware attacks and move laterally across a network. It's a tried-and-true method for causing mayhem.
Best practices for securing remote desktop protocol
Locking down RDP isn't just a good idea—it's a necessity. You wouldn't leave your front door unlocked, so don't leave your digital door open either.
Here are the essential best practices for remote desktop protocol security:
Use Strong, Unique Passwords and Multi-Factor Authentication (MFA): This is your first and best line of defense. A strong password makes brute-force attacks much harder, and MFA stops attackers in their tracks even if they do manage to steal your password. Seriously, enable MFA. Do it now.
Don't Expose RDP to the Internet: Never, ever, ever leave RDP ports open to the public internet. Instead, place it behind a firewall and require users to connect through a Virtual Private Network (VPN). This adds a crucial layer of encrypted protection.
Implement Network Level Authentication (NLA): NLA forces users to authenticate before a full RDP session is established. This helps mitigate brute-force and denial-of-service attacks by preventing resource-intensive sessions from unauthenticated users.
Keep Your Systems Patched: Regularly update your operating systems and software. When a vulnerability like BlueKeep is discovered, developers release patches to fix it. Applying these patches closes the security holes before attackers can exploit them.
Use Lockout Policies: Configure your systems to lock out an account after a certain number of failed login attempts. This can thwart automated brute-force attacks by making them too slow to be effective.
Change the Default RDP Port: While this is more "security through obscurity" than a real fix, changing the RDP port from the default 3389 can reduce the number of automated scans hitting your system. It won't stop a determined attacker, but it can filter out some of the noise.
Putting these practices in place turns RDP from a major liability into the secure, useful tool it was meant to be.
Frequently Asked Questions (FAQs)
No. RDP allows you to control another computer, while a VPN creates a secure, encrypted connection between your device and a private network. For best security, you should use RDP over a VPN connection.
By default, RDP uses TCP port 3389. Because this is so well-known, it's a common target for attackers scanning the internet for vulnerable systems.
It can be, but it's not secure out of the box. Its security depends entirely on how it is configured.
Exposing RDP to the internet with weak credentials is extremely insecure, while using it with MFA behind a VPN is a very secure practice.
Yes! While RDP is a Microsoft protocol, clients and servers are available for macOS, Linux, iOS, and Android. This allows for cross-platform remote access.
Key takeaways
Remote Desktop Protocol is an essential tool for modern IT management and remote work, but its power comes with significant security risks. It's a favorite target for attackers looking for an easy way into a network.
The good news is that securing RDP is straightforward. By following cybersecurity best practices—using strong passwords and MFA, avoiding direct internet exposure, and keeping systems patched—you can protect your environment from compromise. Treat your RDP access like the powerful key it is, and make sure you're the only one who can use it.
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