The following analytic identifies a source process name failing to authenticate with 30 uniquer users. This behavior could represent an adversary performing a Password Spraying attack against an Active Directory environment to obtain initial access or elevate privileges. Active Directory environments can be very different depending on the organization. Users should test this detection and customize the arbitrary threshold when needed. Event 4625 generates on domain controllers, member servers, and workstations when an account fails to logon. Logon Type 2 describes an iteractive logon attempt.
This logic can be used for real time security monitoring as well as threat hunting exercises. This detection will trigger on the potenfially malicious host, perhaps controlled via a trojan or operated by an insider threat, from where a password spraying attack is being executed. This could be a domain controller as well as a member server or workstation.
The analytics returned fields allow analysts to investigate the event further by providing fields like source process name, source account and attempted user accounts.
- Type: TTP
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2021-04-13
- Author: Mauricio Velazco, Splunk
- ID: 9015385a-9c84-11eb-bef2-acde48001122
Kill Chain Phase
- CIS 10
1 2 3 4 5 6 `wineventlog_security` EventCode=4625 Logon_Type=2 ProcessName!="-" | bucket span=5m _time | stats dc(TargetUserName) AS unique_accounts values(TargetUserName) as tried_accounts by _time, ProcessName, SubjectUserName, Computer | rename Computer as dest | where unique_accounts > 30 | `windows_multiple_users_failed_to_authenticate_from_process_filter`
The SPL above uses the following Macros:
windows_multiple_users_failed_to_authenticate_from_process_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
List of fields required to use this analytic.
How To Implement
To successfully implement this search, you need to be ingesting Windows Event Logs from domain controllers aas 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 process failing to authenticate with multiple users is not a common behavior for legitimate user sessions. Possible false positive scenarios include but are not limited to vulnerability scanners and missconfigured systems.
Associated Analytic Story
|49.0||70||70||Potential password spraying attack from $dest$|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
source | version: 2