Author: Melodie Foster

Date: 22nd January 2021

 

The prerequisite for having an RDP server that can be abused is that systems that have RDP authentication also enabled on UDP port 3389 on top of the standard TCP port 3389.

If attackers send malformed UDP packets to the UDP port on an RDP server, it will be reflected to the target of DDoS attack, which will amplify the size of the attack as junk traffic will also be hitting the victim’s system.

Netscout, the firm who sent out this information earlier this week, said this vulnerability is being abused heavily, “as is routinely the case with newer DDoS attack vectors, it appears that after an initial period of employment by advanced attackers with access to bespoke DDoS attack infrastructure, RDP reflection/amplification has been weaponized and added to the arsenals of so-called booter/stresser DDoS-for-hire services, placing it within the reach of the general attacker population.”

Netscout said that it is currently detecting over 14,000 RDP servers that are exposed online and running on UDP port 3389. Researchers are also urging systems administrators who are running RDP servers that are exposed on the internet to take them offline and either switch them to the equivalent TCP port, or put VPNs in front of the RDP servers which would result in less people being able to interact with the systems.[1]

[1] Https://www.zdnet.com/article/windows-rdp-servers-are-being-abused-to-amplify-ddos-attacks/

 

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