Publicly Accessible RDP Service

Description

Detects connections from routable IPs to an RDP listener. Which is indicative of a publicly-accessible RDP service.

Query · sigma

selection:
  id.orig_h|cidr:
  - ::1/128
  - 10.0.0.0/8
  - 127.0.0.0/8
  - 172.16.0.0/12
  - 192.168.0.0/16
  - 169.254.0.0/16
  - 2620:83:8000::/48
  - fc00::/7
  - fe80::/10
condition: not selection

Known false positives

  • 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.
Raw source Publicly Accessible RDP Service · Sigma
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Published by SigmaHQ/sigma ↗, licensed under Detection Rule License 1.1 ↗. Reproduced here unmodified. 
title: Publicly Accessible RDP Service
id: 1fc0809e-06bf-4de3-ad52-25e5263b7623
status: test
description: |
    Detects connections from routable IPs to an RDP listener. Which is indicative of a publicly-accessible RDP service.
author: Josh Brower @DefensiveDepth
date: 2020-08-22
modified: 2024-03-13
tags:
    - attack.lateral-movement
    - attack.t1021.001
logsource:
    product: zeek
    service: rdp
detection:
    selection:
        id.orig_h|cidr:
            - '::1/128'  # IPv6 loopback
            - '10.0.0.0/8'
            - '127.0.0.0/8'
            - '172.16.0.0/12'
            - '192.168.0.0/16'
            - '169.254.0.0/16'
            - '2620:83:8000::/48'
            - 'fc00::/7'  # IPv6 private addresses
            - 'fe80::/10'  # IPv6 link-local addresses
    # approved_rdp:
      # dst_ip:
        # - x.x.x.x
    condition: not selection # and not approved_rdp
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

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