RDP (Remote Desktop Protocol) to the Internet

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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 type: query

Rule indices:

  • filebeat-*
  • packetbeat-*

Severity: low

Risk score: 21

Runs every: 5 minutes

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

Maximum alerts per execution: 100

Tags:

  • Elastic
  • Network

Version: 4 (version history)

Added (Elastic Stack release): 7.6.0

Last modified (Elastic Stack release): 7.9.0

Rule authors: Elastic

Rule license: Elastic License

Potential false positives

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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.

Rule query

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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 172.16.0.0/12 or
192.168.0.0/16 or "::1")

Threat mapping

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Framework: MITRE ATT&CKTM

Rule version history

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Version 4 (7.9.0 release)
  • Updated query, changed from:

    network.transport:tcp and destination.port:3389 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 172.16.0.0/12 or
    192.168.0.0/16 or "::1")
Version 3 (7.7.0 release)
  • Updated query, changed from:

    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) ) )
Version 2 (7.6.1 release)
  • Removed auditbeat-*, packetbeat-*, and winlogbeat-* from the rule indices.