Working remotely has become commonplace. But to stay productive, remote employees often need access to company networks and resources. This is where Remote Desktop Protocol (RDP) comes in handy.
RDP gives remote workers seamless access to work computers and servers from anywhere. But these remote desktop connections also introduce serious security risks that remote employees absolutely need to know about.
In this detailed guide, I‘ll break down how RDP works, major vulnerabilities you need to look out for, and expert-approved tips to keep your remote desktop access secure.
Demystifying RDP: What It Is and How It Works
RDP stands for Remote Desktop Protocol. It was developed by Microsoft and has been around since the early 90s.
At a basic level, RDP allows you to connect to a computer from a remote location and control it as if you were physically sitting in front of that computer. For example, a systems administrator could use RDP to troubleshoot issues or install updates on a company server from their home office.
Some key capabilities provided by RDP:
- Remote control – Access and fully interact with the remote PC or server. Open programs, transfer files, reboot the machine, etc.
- Virtual sessions – Allow multiple remote users to have their own individual desktop sessions on a single host computer. Useful for remote call centers.
- Cross-platform access – RDP clients are available across Windows, macOS, Android, iOS, and Linux for broad remote access.
- Encryption – Uses protocols like TLS 1.2 and CredSSP to encrypt RDP communications and provide confidentiality.
- Authentication – Requires valid credentials to authenticate remote users before allowing them access.
Under the hood, RDP is actually quite complex. When a remote user connects to a machine via RDP, a lot happens behind the scenes:
- The client sends a connection request to the RDP server.
- The server and client exchange configuration settings and security capabilities.
- The client checks that the RDP server is legitimate and trusted.
- Authentication credentials are verified by the server.
- An encrypted data channel is established to pass information.
- The server provides the client a user license confirming permission to connect.
- Both machines confirm compatibility and finalize the connection.
This handshake allows the remote user to see the desktop and control the apps and resources on the remote computer as if they were physically using the machine.
The Pros of Using RDP:
- Allows remote access from anywhere
- Gives full control over the remote machine
- Enables collaborative virtual remote sessions
- Secure encrypted connections
- Works across all major platforms
The Cons of Using RDP:
- Security vulnerabilities if not properly configured
- Can be complex to set up for non-technical users
- Doesn‘t work well over low-bandwidth connections
- Requires compatible RDP client and server software
Serious Security Risks to Watch Out For
RDP offers remote workers easy and flexible access. But these connections also come with substantial security risks, especially if remote desktops are not properly secured.
Some of the major vulnerabilities to be aware of include:
Unsecured RDP Ports Open to the Internet
For RDP to work, TCP port 3389 needs to be open on the target computer. Unfortunately, it‘s shockingly common for companies to leave RDP ports exposed directly to the public internet without any type of authentication or encryption in place.
This allows hackers to easily find open RDP ports and attempt to brute force their way in. According to a report by cybersecurity firm Coveware, exposed RDP ports account for 37% of ransomware attacks. Once in, attackers can steal data, install viruses, or launch crippling ransomware attacks.
Weak or Default Credentials
Secure passwords are a must for RDP access. But weak credentials like "Password123" or unchanged default passwords make it trivial for attackers to gain access. Cybercriminals can easily automate guessing of common passwords.
Mandatory password complexity policies, frequent password changes, and avoiding password reuse across accounts helps prevent unauthorized RDP access.
No Network Level Authentication
By default, RDP doesn‘t require logins during the initial network connection phase. So attackers can repeatedly initiate sessions and brute force logins without any account lockouts.
Using Network Level Authentication (NLA) closes this security gap by forcing authentication right when the first network connection is attempted before a full RDP session can be established.
Susceptible to Man-in-the-Middle (MiTM) Attacks
The built-in encryption protocols used by RDP like TLS and CredSSP have also proven vulnerable to MiTM attacks. These allow hackers to intercept and decrypt RDP communications by posing as legitimate users.
Routing RDP through a VPN connection adds an extra layer of end-to-end encryption that can prevent MiTM attacks against RDP encryption protocols.
Expert-Approved Tips to Lock Down RDP Security
Securing RDP doesn‘t have to be complicated. Here are great tips from cybersecurity experts to lock down remote desktop access:
Close Unnecessary RDP Ports
Audit open RDP ports across your network and close down any unauthorized or unprotected internet-facing connections. Disable RDP on devices that don‘t require it.
Mandate Strong Passwords
Enforce password complexity requirements, periodic password changes, and educate users against reusing passwords across accounts.
Use Multi-Factor Authentication (MFA)
Require employees to use MFA options like Duo or Yubikey when connecting via RDP for an added layer of protection.
Limit Login Attempts
Restrict the number of failed login attempts to 3-5 before locking out users. This frustrates brute force attacks. Whitelist office IP ranges to avoid accidental lockouts.
Monitor & Log RDP Access
Tools like RDP Guard enable logging of connection attempts, active session monitoring, source IP whitelisting/blacklisting and closing of suspicious connections.
Route Connections Through a VPN
Mandate that remote workers connect via a VPN before accessing company RDP servers. This encrypts traffic end-to-end and prevents MiTM attacks.
Isolate Vendor Access
Exercise caution when granting third-party vendors RDP access. Segment their access through jump boxes and limit access only to essential systems.
Stay Up-to-Date with Patching
Promptly apply security updates for operating systems, remote access software, and other applications. Unpatched vulnerabilities are a magnet for exploits.
More Secure Alternatives to RDP Access
If your use case permits it, other technologies offer more secure remote access alternatives:
- Secure Shell (SSH) – Provides command line access with end-to-end encrypted connections resistant to MiTM attacks.
- Virtual Private Network (VPN) – All traffic is encrypted between company and employee devices via VPN tunnel.
- Virtual Desktop Infrastructure (VDI) – Endpoint devices simply access virtual desktops hosted securely in the data center rather than locally.
- Browser Isolation – Remote browser access without any data leaving the network perimeter, only safe visuals streamed to users.
The Bottom Line
RDP offers indispensable connectivity for remote employees. But convenience comes with risks if security is not baked into RDP configurations.
Following the tips outlined in this guide will help secure remote desktop access without compromising productivity:
- Close unneeded RDP ports and disable internet exposure
- Enforce strong passwords and multi-factor authentication
- Monitor, log, and limit remote login attempts
- Route connections through VPNs for encryption
- Isolate third-party vendor access
- Evaluate more secure alternatives where possible
Staying vigilant, keeping software updated, and properly hardening RDP servers will go a long way in protecting remote desktop infrastructure against cyber attacks.
What questions do you have about securing RDP access for remote work? I‘m happy to help explain best practices in more detail. Feel free to ask in the comments!