title: Publicly Accessible RDP Service
id: 1fc0809e-06bf-4de3-ad52-25e5263b7623
status: experimental
description: Detects connections from routable IPs to an RDP listener - which is indicative of a publicly-accessible RDP service.
references:
    - https://attack.mitre.org/techniques/T1021/001/
tags:
    - attack.t1021.001
author: 'Josh Brower @DefensiveDepth'
date: 2020/08/22
modified: 2021/11/14
logsource:
    product: zeek
    service: rdp
detection:
    selection:
      id.orig_h|startswith:
        - '192.168.'
        - '10.'
        - '172.16.'
        - '172.17.'
        - '172.18.'
        - '172.19.'
        - '172.20.'
        - '172.21.'
        - '172.22.'
        - '172.23.'
        - '172.24.'
        - '172.25.'
        - '172.26.'
        - '172.27.'
        - '172.28.'
        - '172.29.'
        - '172.30.'
        - '172.31.'
    #approved_rdp:
      #dst_ip:
        #- x.x.x.x
    condition: not selection #and not approved_rdp
fields:
    - id.orig_h
    - id.resp_h
falsepositives:
    - Although it is recommended to NOT have RDP exposed to the internet, verify that this is a) allowed b) the server has not already been compromised via some brute force or remote exploit since it has been exposed to the internet. Work to secure the server if you are unable to remove it from being exposed to the internet.
level: high
