
title: Multiple Users Remotely Failing To Authenticate From Single Source
author: Mauricio Velazco
date: 2021/06/01
description: Detects a source system failing to authenticate against a remote host
  with multiple users.
detection:
  SELECTION_1:
    EventID: 4625
  SELECTION_2:
    LogonType: 3
  SELECTION_3:
    IpAddress: '-'
  condition: ((SELECTION_1 and SELECTION_2) and  not (SELECTION_3)) | count(TargetUserName)
    by IpAddress > 10
falsepositives:
- Terminal servers
- Jump servers
- Other multiuser systems like Citrix server farms
- Workstations with frequently changing users
id: add2ef8d-dc91-4002-9e7e-f2702369f53a
level: medium
logsource:
  product: windows
  service: security
modified: 2021/07/09
references:
- https://docs.splunk.com/Documentation/ESSOC/3.22.0/stories/UseCase#Active_directory_password_spraying
status: experimental
tags:
- attack.t1110.003
- attack.initial_access
- attack.privilege_escalation
ruletype: SIGMA
