⚠️ WARNING THIS IS A EXPERIMENTAL DETECTION
We have not been able to test, simulate, or build datasets for this detection. Use at your own risk. This analytic is NOT supported.
The following hunting analytic leverages Event ID 4624,
An account was successfully logged on, to identify an unusual number of remote authentication attempts coming from one source. An endpoint authenticating to a large number of remote endpoints could represent malicious behavior like lateral movement, malware staging, reconnaissance, etc.
The detection calculates the standard deviation for each host and leverages the 3-sigma statistical rule to identify an unusual high number of authentication events. To customize this analytic, users can try different combinations of the
bucket span time, the calculation of the
upperBound field as well as the Outlier calculation. This logic can be used for real time security monitoring as well as threat hunting exercises.\
- Type: Hunting
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2021-12-01
- Author: Mauricio Velazco, Splunk
- ID: acb5dc74-5324-11ec-a36d-acde48001122
|T1078||Valid Accounts||Defense Evasion, Persistence, Privilege Escalation, Initial Access|
`wineventlog_security` EventCode=4624 Logon_Type=3 Account_Name!="*$" | eval Source_Account = mvindex(Account_Name, 1) | bucket span=2m _time | stats dc(ComputerName) AS unique_targets values(ComputerName) as target_hosts by _time, Source_Network_Address, Source_Account | eventstats avg(unique_targets) as comp_avg , stdev(unique_targets) as comp_std by Source_Network_Address, Source_Account | eval upperBound=(comp_avg+comp_std*3) | eval isOutlier=if(unique_targets >10 and unique_targets >= upperBound, 1, 0) `unusual_number_of_remote_endpoint_authentication_events_filter`
Associated Analytic Story
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.
Kill Chain Phase
- Lateral Movement
Known False Positives
An single endpoint authenticating to a large number of hosts is not common behavior. Possible false positive scenarios include but are not limited to vulnerability scanners, jump servers and missconfigured systems.
source | version: 1