Creation of a Hidden Local User Account

Elastic Stack Serverless Security

Identifies the creation of a hidden local user account by appending the dollar sign to the account name. This is sometimes done by attackers to increase access to a system and avoid appearing in the results of accounts listing using the net users command.

Rule type: eql

Rule indices:

• winlogbeat-*
• logs-endpoint.events.*
• logs-windows.*

Severity: high

Risk score: 73

Runs every: 5m

Searches indices from: now-9m (https://www.elastic.co/guide/en/elasticsearch/reference/current/common-options.html#date-math[Date Math format], see also Additional look-back time)

Maximum alerts per execution: 100

References:

• https://web.archive.org/web/20230329153858/https://blog.menasec.net/2019/02/threat-hunting-6-hiding-in-plain-sights_8.html
• https://github.com/CyberMonitor/APT_CyberCriminal_Campagin_Collections/tree/master/2020/2020.12.15.Lazarus_Campaign

Tags:

• Elastic
• Host
• Windows
• Threat Detection
• Persistence

Version: 2

Rule authors:

• Elastic

Rule license: Elastic License v2

registry where registry.path : "HKLM\\SAM\\SAM\\Domains\\Account\\Users\\Names\\*$\\"

Framework: MITRE ATT&CKTM

• Tactic:

  • Name: Persistence
  • ID: TA0003
  • Reference URL: https://attack.mitre.org/tactics/TA0003/

• Technique:

  • Name: Create Account
  • ID: T1136
  • Reference URL: https://attack.mitre.org/techniques/T1136/

• Sub-technique:

  • Name: Local Account
  • ID: T1136.001
  • Reference URL: https://attack.mitre.org/techniques/T1136/001/