Windows RDP (TCP 3389) Initiated Connections to HTTP/HTTPS Ports (80/443)

title: Windows RDP (TCP 3389) Initiated Connections to HTTP/HTTPS Ports (80/443)
id: 94a1e9e4-8324-42be-aff5-804fe995010a
status: test
description: This rule flags network connections where svchost.exe initiates traffic from TCP source port 3389 to destination ports 80 or 443. Such RDP-to-web port targeting is noteworthy because it can indicate tunneling or proxy-like behavior that blends remote access inside typical web traffic. It relies on Windows network connection telemetry capturing process context (svchost.exe) and source/destination port numbers.
references:
  - https://twitter.com/tekdefense/status/1519711183162556416?s=12&t=OTsHCBkQOTNs1k3USz65Zg
  - https://www.mandiant.com/resources/bypassing-network-restrictions-through-rdp-tunneling
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/network_connection/net_connection_win_rdp_to_http.yml
author: Florian Roth (Nextron Systems), Huntrule Team
date: 2022-04-29
modified: 2022-07-14
tags:
  - attack.command-and-control
  - attack.t1572
  - attack.lateral-movement
  - attack.t1021.001
  - car.2013-07-002
logsource:
  category: network_connection
  product: windows
detection:
  selection:
    Image|endswith: \svchost.exe
    Initiated: "true"
    SourcePort: 3389
    DestinationPort:
      - 80
      - 443
  condition: selection
falsepositives:
  - Unknown
level: high
license: DRL-1.1
related:
  - id: b1e5da3b-ca8e-4adf-915c-9921f3d85481
    type: derived