Techniques
Sample rules
Windows Multiple Users Failed To Authenticate From Process
- source: splunk
- technicques:
- T1110.003
- T1110
Description
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.
Detection logic
`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`
Windows Unusual Count Of Users Failed To Authenticate From Process
- source: splunk
- technicques:
- T1110.003
- T1110
Description
The following analytic identifies a source process name failing to authenticate with multiple users. This behavior could represent an adversary performing a Password Spraying attack against an Active Directory environment to obtain initial access or elevate privileges. Event 4625 generates on domain controllers, member servers, and workstations when an account fails to logon. Logon Type 2 describes an iteractive logon attempt.
The detection calculates the standard deviation for each host and leverages the 3-sigma statistical rule to identify an unusual number of users. To customize this analytic, users can try different combinations of the bucket span time and the calculation of the upperBound field. 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.
Detection logic
`wineventlog_security` EventCode=4625 Logon_Type=2 ProcessName!="-"
| bucket span=2m _time
| stats dc(TargetUserName) AS unique_accounts values(TargetUserName) as user by _time, ProcessName, SubjectUserName, Computer
| eventstats avg(unique_accounts) as comp_avg , stdev(unique_accounts) as comp_std by ProcessName, SubjectUserName, Computer
| eval upperBound=(comp_avg+comp_std*3)
| eval isOutlier=if(unique_accounts > 10 and unique_accounts >= upperBound, 1, 0)
| search isOutlier=1
| `windows_unusual_count_of_users_failed_to_authenticate_from_process_filter`