Suspicious Rundll32 Internet Connection (via network_connection)

title: Suspicious Rundll32 Internet Connection (via network_connection)
id: c2d7b749-1237-5be0-8b68-377de10554dd
status: stable
description: This rule detects a rundll32 that communicates with public IP addresses
references:
    - https://attack.mitre.org/techniques/T1218/011/
    - https://www.hybrid-analysis.com/sample/759fb4c0091a78c5ee035715afe3084686a8493f39014aea72dae36869de9ff6?environmentId=100
author: Huntrule Team
date: 2026-06-05
tags:
    - attack.stealth
    - attack.t1218.011
    - attack.execution
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        Image|endswith: '\rundll32.exe'
        Initiated: 'true'
    filter_main_local_ranges:
        DestinationIp|cidr:
            - '127.0.0.0/8'
            - '10.0.0.0/8'
            - '172.16.0.0/12'
            - '192.168.0.0/16'
            - '169.254.0.0/16'
            - '::1/128'
            - 'fe80::/10'
            - 'fc00::/7'
    filter_main_ms_ranges:
        DestinationIp|cidr:
            - '20.0.0.0/8'
            - '51.103.0.0/16'
            - '51.104.0.0/16'
            - '51.105.0.0/16'
    filter_main_app_sdb:
        CommandLine|endswith: '\system32\PcaSvc.dll,PcaPatchSdbTask'
    filter_main_azure_managed:
        SourceHostname|endswith: '.internal.cloudapp.net'
    filter_main_svchost_update_processes:
        ParentImage: 'C:\Windows\System32\svchost.exe'
        DestinationPort: 443
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Unknown
level: medium