Outbound Network Connection To Public IP Via Winlogon — Sigma Rule

Rule metadata and linked tags

Author: Christopher Peacock @securepeacock, SCYTHE @scythe_io. Source status: test; severity: medium. Source dates: 2023-04-28 / 2024-03-12.

{
  "category": "network_connection",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 249c59705e2234fb32529d913dbeee4d26eba33d6d3f5cb1c392e0ef461f04e4

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Outbound Network Connection To Public IP Via Winlogon
id: 7610a4ea-c06d-495f-a2ac-0a696abcfd3b
status: test
description: Detects a "winlogon.exe" process that initiate network communications with public IP addresses
references:
    - https://www.microsoft.com/en-us/security/blog/2023/04/11/guidance-for-investigating-attacks-using-cve-2022-21894-the-blacklotus-campaign/
author: Christopher Peacock @securepeacock, SCYTHE @scythe_io
date: 2023-04-28
modified: 2024-03-12
tags:
    - attack.execution
    - attack.command-and-control
    - attack.stealth
    - attack.t1218.011
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        Image|endswith: '\winlogon.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'  # IPv6 loopback
            - 'fe80::/10'  # IPv6 link-local addresses
            - 'fc00::/7'  # IPv6 private addresses
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Communication to other corporate systems that use IP addresses from public address spaces
level: medium

Original YAML and metadata in JSON

False positives

• Communication to other corporate systems that use IP addresses from public address spaces

Source references

• https://www.microsoft.com/en-us/security/blog/2023/04/11/guidance-for-investigating-attacks-using-cve-2022-21894-the-blacklotus-campaign/