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Description

The following analytic detects the creation of local administrator accounts using the net.exe command to mitigate the risks associated with unauthorized access and prevent further damage to the environment by responding to potential threats earlier and taking appropriate actions to protect the organization's systems and data. This detection is made by a Splunk query to search for processes with the name net.exe or net1.exe that include the "/add" parameter in their process name. This detection is important because the creation of unauthorized local user accounts might indicate that an attacker has successfully created a new user account and is trying to gain persistent access to a system or escalate their privileges for data theft, or other malicious activities. False positives might occur since there might be legitimate uses of the net.exe command and the creation of user accounts in certain circumstances. You must consider the context of the activity and other indicators of compromise before taking any action. For next steps, review the details of the identified process, including the user, parent process, and parent process name. Examine any relevant on-disk artifacts and look for concurrent processes to determine the source of the attack.

  • Type: Anomaly

  • Product: Splunk Behavioral Analytics

  • Last Updated: 2023-10-23
  • Author: Teoderick Contreras, Mauricio Velazco, Splunk
  • ID: 3e66edb4-b4dc-4b65-b57f-779a88d7d1d9

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1136.001 Local Account Persistence
T1136 Create Account Persistence
Kill Chain Phase
  • Installation
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


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 $main = from source  
| eval timestamp = time  
| eval metadata_uid = metadata.uid  
| eval process_pid = process.pid 
| eval process_file = process.file 
| eval process_file_path = process_file.path 
| eval process_file_name = lower(process_file.name) 
| eval process_cmd_line = process.cmd_line 
| eval actor_user = actor.user 
| eval actor_user_name = actor_user.name 
| eval actor_process = actor.process 
| eval actor_process_pid = actor_process.pid 
| eval actor_process_file = actor_process.file 
| eval actor_process_file_path = actor_process_file.path 
| eval actor_process_file_name = actor_process_file.name 
| eval device_hostname = device.hostname 
| where process_cmd_line LIKE "%user%" AND process_cmd_line LIKE "%/add%" AND (process_file_name IN ("net.exe", "net1.exe")) --finding_report--

Macros

The SPL above uses the following Macros:

:information_source: create_local_user_accounts_using_net_exe_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • process.pid
  • process.file.path
  • process.file.name
  • process.cmd_line
  • actor.user.name
  • actor.process.pid
  • actor.process.file.path
  • actor.process.file.name
  • device.hostname

How To Implement

To successfully implement this search, you need to be ingesting logs with the process name, parent process, and command-line executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA. Tune and filter known instances where renamed net.exe may be used.

Known False Positives

System administrators or scripts may add user accounts via this technique. Filter as needed.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
9.0 30 30 An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$ attempting to add a user to the local group.

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

source | version: 6