Windows Process Reconnaissance via net.exe Group/Account Queries

title: Windows Process Reconnaissance via net.exe Group/Account Queries
id: 72ac4771-4ee6-4a8b-8750-50922072b9f3
status: test
description: This rule flags suspicious Windows command-line activity using net.exe (or net1.exe) focused on querying local groups/domain group administration and enumerating accounts. Such recon helps attackers identify privileged users, roles, and available targets before further exploitation. It relies on process creation telemetry, matching the executable name and specific command-line keywords and flags related to group and account discovery.
references:
  - https://redcanary.com/blog/how-one-hospital-thwarted-a-ryuk-ransomware-outbreak/
  - https://thedfirreport.com/2020/10/18/ryuk-in-5-hours/
  - https://research.nccgroup.com/2022/08/19/back-in-black-unlocking-a-lockbit-3-0-ransomware-attack/
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_net_groups_and_accounts_recon.yml
author: Florian Roth (Nextron Systems), omkar72, @svch0st, Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2019-01-16
modified: 2023-03-02
tags:
  - attack.discovery
  - attack.t1087.001
  - attack.t1087.002
logsource:
  category: process_creation
  product: windows
detection:
  selection_img:
    - Image|endswith:
        - \net.exe
        - \net1.exe
    - OriginalFileName:
        - net.exe
        - net1.exe
  selection_group_root:
    CommandLine|contains:
      - " group "
      - " localgroup "
  selection_group_flags:
    CommandLine|contains:
      - domain admins
      - " administrator"
      - " administrateur"
      - enterprise admins
      - Exchange Trusted Subsystem
      - Remote Desktop Users
      - Utilisateurs du Bureau à distance
      - Usuarios de escritorio remoto
      - " /do"
  filter_group_add:
    CommandLine|contains: " /add"
  selection_accounts_root:
    CommandLine|contains: " accounts "
  selection_accounts_flags:
    CommandLine|contains: " /do"
  condition: selection_img and ((all of selection_group_* and not filter_group_add) or all of selection_accounts_*)
falsepositives:
  - Inventory tool runs
  - Administrative activity
level: medium
license: DRL-1.1
related:
  - id: d95de845-b83c-4a9a-8a6a-4fc802ebf6c0
    type: derived