Windows Multiple Users Fail To Authenticate Wth ExplicitCredentials

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Description

The following analytic identifies a source user failing to authenticate with 30 unique users using explicit credentials on a host. It leverages Windows Event 4648, which is generated when a process attempts an account logon by explicitly specifying account credentials. This detection is significant as it may indicate a Password Spraying attack, where an adversary attempts to gain initial access or elevate privileges within an Active Directory environment. If confirmed malicious, this activity could lead to unauthorized access, privilege escalation, and potential compromise of sensitive information.

• Type: TTP

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

• Last Updated: 2024-05-17
• Author: Mauricio Velazco, Splunk
• ID: e61918fa-9ca4-11eb-836c-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

Search

 `wineventlog_security` EventCode=4648 Caller_User_Name!=*$ Target_User_Name!=*$ 
| bucket span=5m _time 
| stats dc(Target_User_Name) AS unique_accounts values(Target_User_Name) as  tried_account by _time, Computer, Caller_User_Name 
| where unique_accounts > 30 
| `windows_multiple_users_fail_to_authenticate_wth_explicitcredentials_filter`

Macros

The SPL above uses the following Macros:

• wineventlog_security

windows_multiple_users_fail_to_authenticate_wth_explicitcredentials_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
• Target_User_Name
• Caller_User_Name
• Computer

How To Implement

To successfully implement this search, you need to be ingesting Windows Event Logs from domain controllers 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 source user failing attempting to authenticate multiple users on a host is not a common behavior for regular systems. Some applications, however, may exhibit this behavior in which case sets of users hosts can be added to an allow list. Possible false positive scenarios include systems where several users connect to like Mail servers, identity providers, remote desktop services, Citrix, etc.

Associated Analytic Story

• Active Directory Password Spraying
• Insider Threat
• Volt Typhoon

RBA

Risk Score	Impact	Confidence	Message
49.0	70	70	Potential password spraying attack from $Computer$

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

• https://attack.mitre.org/techniques/T1110/003/
• https://docs.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4648
• https://docs.microsoft.com/en-us/windows/security/threat-protection/auditing/basic-audit-logon-events

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