Microsoft RDP Under Attack: A Surge in Scans Puts Your Network at Risk
Cybersecurity threat monitors have identified a significant and coordinated spike in scanning activity targeting a critical component of many business networks: Microsoft’s Remote Desktop Protocol (RDP). This isn’t random background noise; this is a large-scale, methodical campaign by attackers to find and compromise vulnerable RDP authentication servers across the globe.
If your organization uses RDP for remote access, this is a direct and immediate threat. These scans are often the first step in a chain of events that can lead to data breaches, ransomware deployment, and complete network compromise. Understanding the threat and taking immediate action is crucial to protecting your digital assets.
What’s Happening? A Coordinated Scanning Campaign
Threat intelligence shows a massive increase in automated probes specifically targeting TCP port 3389, the default port for RDP. Attackers are systematically searching the internet for servers with this port open, attempting to identify systems that are poorly configured or unpatched.
The primary goal of these scans is reconnaissance. Cybercriminals are building lists of potential targets for more focused attacks, including:
- Brute-force attacks to guess weak or common passwords.
- Exploitation of known vulnerabilities like BlueKeep or DejaBlue.
- Credential stuffing attacks using stolen usernames and passwords from other data breaches.
Once attackers gain a foothold through an exposed RDP server, they can move laterally through your network, escalate their privileges, and deploy malicious payloads like ransomware.
Why RDP is a Prime Target for Attackers
Remote Desktop Protocol is an incredibly useful tool, allowing administrators and employees to access their work systems from anywhere. Its popularity, however, is precisely what makes it such an attractive target for cybercriminals.
Any RDP server exposed directly to the internet is a high-value target. Attackers know that a single compromised RDP account can provide them with the “keys to the kingdom,” granting them the same level of access as a legitimate user. The shift to remote and hybrid work models has only increased the number of RDP instances online, expanding the attack surface for these malicious campaigns.
Actionable Steps to Secure Your RDP Environment
The good news is that securing RDP is achievable with a proactive, defense-in-depth approach. Do not wait for an attack to happen. Review your remote access policies and implement these essential security measures immediately.
1. Never Expose RDP Directly to the Internet
This is the single most important step you can take. There is almost no valid reason for RDP (port 3389) to be open to the entire world. Instead, require users to connect through a secure gateway first.
- Actionable Tip: Place your RDP servers behind a Virtual Private Network (VPN) or a secure Remote Desktop Gateway. This forces users to authenticate through a secure, encrypted tunnel before they can even attempt to connect to the RDP server itself.
2. Enforce Network Level Authentication (NLA)
NLA is a critical security feature that requires a user to authenticate before a full RDP session is established with the server.
- Actionable Tip: Enable NLA on all your systems. This simple step can mitigate many brute-force attacks and deny attackers the ability to exploit certain pre-authentication vulnerabilities.
3. Implement Strong Passwords and Multi-Factor Authentication (MFA)
Weak and reused passwords are one of the most common entry points for attackers.
- Actionable Tip: Enforce a strong password policy that requires complexity and regular changes. More importantly, implement multi-factor authentication (MFA) for all remote access. MFA adds a vital layer of security that can block an attack even if the password has been compromised.
4. Use a Firewall and Restrict Access
Your firewall is your first line of defense. Use it to strictly control who can access your RDP servers.
- Actionable Tip: Configure your firewall rules to only allow RDP connections from specific, trusted IP addresses. If your users have dynamic IP addresses, a VPN is a much more secure solution.
5. Keep Your Systems Patched and Updated
Attackers frequently exploit known vulnerabilities in RDP for which patches are already available.
- Actionable Tip: Ensure you have a robust patch management process. Regularly check for and apply all Windows security updates to protect against known exploits.
6. Implement Account Lockout Policies
A strong account lockout policy can thwart automated brute-force password attacks.
- Actionable Tip: Configure your system to automatically lock a user account after a set number of failed login attempts. This stops attackers from being able to guess passwords indefinitely.
A Proactive Defense is Your Best Strategy
The current surge in RDP scanning is a clear warning sign. Cybercriminals are actively hunting for easy targets. By taking these proactive security measures, you can significantly reduce your attack surface and ensure your network doesn’t become another statistic. Review your remote access security posture today before it’s too late.
Source: https://www.bleepingcomputer.com/news/security/surge-in-coordinated-scans-targets-microsoft-rdp-auth-servers/
