Remote Desktop Protocol (RDP) is a proprietary network protocol that allows an individual to control the resources and data of a computer over the Internet
Threat actors Started exploiting RDP protocol since 2016 and compromised various targets around the world and used it to infect with malware and ransomware.
RDP protocol helps to provide complete control over the desktop of a remote machine by transmitting input such as mouse movements and keystrokes and sending back a graphical user interface.
In this case, username and password will be shared by both local and remote machine by mutual authentication in order to share both desktop access.
During the operation, attackers infiltrate the RDP connection of both machine and inject the malware or ransomware into the remote machine.
According to US-CERT, Cyber criminal selling stolen RDP access in various dark web underground marketplace.
— US-CERT (@USCERT_gov) September 28, 2018
Previous Cyber Attacks using RDP Protocol
These are following Ransomware attacks are the conducted by threat actors by infiltrating the RDP Protocol.
CrySiS Ransomware: CrySIS ransomware was distributed using open RDP Ports, brute-force and dictionary attacks to gain unauthorized remote access to the victim’s computer.
CryptON Ransomware: CryptON ransomware utilizes brute-force attacks to gain access to RDP sessions, then allows a threat actor to manually execute malicious programs on the compromised machine.
Samsam Ransomware: Samsam ransomware uses a wide range of exploits, including ones attacking RDP-enabled machines, to perform brute-force attacks.
Remote Desktop Protocol Vulnerabilities
- Weak passwords – passwords using dictionary words or do not include a mixture of uppercase/lowercase letters, numbers, and special characters – are vulnerable to brute-force attacks and dictionary attacks.
- Outdated versions of RDP may use flawed CredSSP, the encryption mechanism, thus enabling a potential man-in-the-middle attack.
- Allowing unrestricted access to the default RDP port (TCP 3389).
- Allowing unlimited login attempts to a user account.
Mitigation Suggested by FBI & DHS
- Audit your network for systems using RDP for remote communication. Disable the service if unneeded or install available patches.
- Place open port RDP behind the firewall and require the user to access via VPN and firewall.
- Verify all cloud-based virtual machine instances with a public IP do not have open RDP ports, specifically port 3389.
- Enable strong passwords and account lockout policies to defend against brute-force attacks.
- Apply two-factor authentication, where possible.
- Apply system and software updates regularly.
- Maintain a good backup strategy.
- Ensure third parties that require RDP access are required to follow internal policies on remote access.
In this case, Federal Bureau of Investigation (FBI) and Department of Homeland Security (DHS) warned to businesses to understand what remote accesses their networks allow and take steps to reduce the likelihood of compromise.