RDP (Remote Desktop Protocol) to the Internetedit

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 back-door vector.

Rule indices:

  • filebeat-*

Severity: low

Risk score: 21

Runs every: 5 minutes

Searches indices from: now-6m (Date Math format, see also Additional look-back time)

Maximum signals per execution: 100

Tags:

  • Elastic
  • Network

Rule version: 2 (version history)

Added (Elastic Stack release): 7.6.0

Last modified (Elastic Stack release): 7.6.1

Potential false positivesedit

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 workflows such as remote access and support for specialized software products and servers. Such workflows are usually known and not unexpected. Usage that is unfamiliar to server or network owners can be unexpected and suspicious.

Rule queryedit

network.transport: tcp and destination.port: 3389 and (
network.direction: outbound or ( 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 172.16.0.0/12 or 192.168.0.0/16) ) )

Threat mappingedit

Framework: MITRE ATT&CKTM