title: Dllhost Internet Connection
id: cfed2f44-16df-4bf3-833a-79405198b277
status: experimental
description: Detects Dllhost that communicates with public IP addresses
references:
    - https://github.com/Neo23x0/sigma/blob/master/rules/windows/network_connection/sysmon_rundll32_net_connections.yml
author: bartblaze
date: 2020/07/13
modified: 2020/08/24
tags:
    - attack.defense_evasion
    - attack.t1218
    - attack.execution
    - attack.t1559.001  
    - attack.t1175  # an old one  
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        Image|endswith: '\dllhost.exe'
        Initiated: 'true'
    filter:
        DestinationIp|startswith:
            - '10.'
            - '192.168.'
            - '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.'
            - '127.'
    condition: selection and not filter
falsepositives:
    - Communication to other corporate systems that use IP addresses from public address spaces
level: medium