New User Created Via Net.EXE With Never Expire Option

Status: test
Severity: high
Log source: category process_creation, product windows
Author: Nasreddine Bencherchali (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects creation of local users via the net.exe command with the option "never expire"

Known false positives

Unlikely

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1136.001` Create Account: Local Account

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation

Rule body

title: New User Created Via Net.EXE With Never Expire Option
id: b9f0e6f5-09b4-4358-bae4-08408705bd5c
related:
    - id: cd219ff3-fa99-45d4-8380-a7d15116c6dc
      type: derived
status: test
description: Detects creation of local users via the net.exe command with the option "never expire"
references:
    - https://thedfirreport.com/2022/07/11/select-xmrig-from-sqlserver/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-07-12
modified: 2023-02-21
tags:
    - attack.persistence
    - attack.t1136.001
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith:
              - '\net.exe'
              - '\net1.exe'
        - OriginalFileName:
              - 'net.exe'
              - 'net1.exe'
    selection_cli:
        CommandLine|contains|all:
            - 'user'
            - 'add'
            - 'expires:never'
    condition: all of selection_*
falsepositives:
    - Unlikely
level: high

Stages and Predicates

Stage 0: `condition`

all of selection_*

Stage 1: `selection_img`

selection_img:
    - Image|endswith:
          - '\net.exe'
          - '\net1.exe'
    - OriginalFileName:
          - 'net.exe'
          - 'net1.exe'

Stage 2: `selection_cli`

selection_cli:
    CommandLine|contains|all:
        - 'user'
        - 'add'
        - 'expires:never'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`add` corpus 34 (sigma 26, splunk 4, chronicle 2, kusto 2) `expires:never` `user` corpus 17 (sigma 11, splunk 4, chronicle 2)	`field:"CommandLine" kind:match`
`Image`	ends_with	`\net.exe` corpus 49 (sigma 49) `\net1.exe` corpus 47 (sigma 47)	`field:"Image" kind:ends_with`
`OriginalFileName`	eq	`net.exe` corpus 31 (sigma 19, elastic 10, splunk 2) `net1.exe` corpus 44 (sigma 19, splunk 19, elastic 6)	`field:"OriginalFileName" kind:eq`

New User Created Via Net.EXE With Never Expire Option

Known false positives

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection_img

Stage 2: selection_cli

Indicators

Stage 0: `condition`

Stage 1: `selection_img`

Stage 2: `selection_cli`