LoFP LoFP / rdp connections may be made directly to internet destinations in order to access windows cloud server instances but such connections are usually made only by engineers. in such cases, only rdp gateways, bastions or jump servers may be expected internet destinations and can be exempted from this rule. rdp may be required by some work-flows such as remote access and support for specialized software products and servers. such work-flows are usually known and not unexpected. usage that is unfamiliar to server or network owners can be unexpected and suspicious.

Techniques

Sample rules

RDP (Remote Desktop Protocol) to the Internet

Description

This rule detects network events that may indicate the use of RDP traffic to the Internet. RDP is commonly used by system administrators to remotely control a system for maintenance or to use shared resources. It should almost never be directly exposed to the Internet, as it is frequently targeted and exploited by threat actors as an initial access or backdoor vector.

Detection logic

event.category:(network or network_traffic) and network.transport:tcp and (destination.port:3389 or event.dataset:zeek.rdp) and
  source.ip:(
    10.0.0.0/8 or
    172.16.0.0/12 or
    192.168.0.0/16
  ) and
  not destination.ip:(
    10.0.0.0/8 or
    127.0.0.0/8 or
    169.254.0.0/16 or
    172.16.0.0/12 or
    192.168.0.0/16 or
    224.0.0.0/4 or
    "::1" or
    "FE80::/10" or
    "FF00::/8"
  )