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Description

The following analytic identifies a source host failing to authenticate against a remote host with 30 unique users. It leverages Windows Event 4625 with Logon Type 3, indicating remote authentication attempts. This behavior is significant as it may indicate a Password Spraying attack, where an adversary attempts to gain initial access or elevate privileges in an Active Directory environment. If confirmed malicious, this activity could lead to unauthorized access, privilege escalation, and potential compromise of sensitive information. This detection is crucial for real-time security monitoring and threat hunting.

  • Type: TTP

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2024-05-28
  • Author: Mauricio Velazco, Splunk
  • ID: 80f9d53e-9ca1-11eb-b0d6-acde48001122

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1110.003 Password Spraying Credential Access
T1110 Brute Force Credential Access
Kill Chain Phase
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


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 `wineventlog_security` EventCode=4625 Logon_Type=3 IpAddress!="-" 
| bucket span=5m _time 
| stats dc(TargetUserName) AS unique_accounts values(TargetUserName) as tried_accounts by _time, IpAddress, Computer 
| rename Computer as dest
| where unique_accounts > 30 
| `windows_multiple_users_remotely_failed_to_authenticate_from_host_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_multiple_users_remotely_failed_to_authenticate_from_host_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.

  • _time
  • EventCode
  • Logon_Type
  • TargetUserName
  • Computer
  • IpAddress

How To Implement

To successfully implement this search, you need to be ingesting Windows Event Logs from domain controllers as as well as member servers and workstations. The Advanced Security Audit policy setting Audit Logon within Logon/Logoff needs to be enabled.

Known False Positives

A host failing to authenticate with multiple valid users against a remote host is not a common behavior for legitimate systems. Possible false positive scenarios include but are not limited to vulnerability scanners, remote administration tools, missconfigyred systems, etc.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
49.0 70 70 Potential password spraying attack on $dest$

: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: 3