ID | Technique | Tactic |
---|---|---|
T1135 | Network Share Discovery | Discovery |
T1078 | Valid Accounts | Defense Evasion |
Detection: Windows Large Number of Computer Service Tickets Requested
Description
The following analytic detects a high volume of Kerberos service ticket requests, specifically more than 30, from a single source within a 5-minute window. It leverages Event ID 4769, which logs when a Kerberos service ticket is requested, focusing on requests with computer names as the Service Name. This behavior is significant as it may indicate malicious activities such as lateral movement, malware staging, or reconnaissance. If confirmed malicious, an attacker could gain unauthorized access to multiple endpoints, potentially compromising the entire network.
Search
1`wineventlog_security` EventCode=4769 ServiceName="*$" TargetUserName!="*$"
2| bucket span=5m _time
3| stats dc(ServiceName) AS unique_targets values(ServiceName) as host_targets by _time, IpAddress, TargetUserName
4| where unique_targets > 30
5| `windows_large_number_of_computer_service_tickets_requested_filter`
Data Source
Name | Platform | Sourcetype | Source | Supported App |
---|---|---|---|---|
Windows Event Log Security 4769 | Windows | 'xmlwineventlog' |
'XmlWinEventLog:Security' |
N/A |
Macros Used
Name | Value |
---|---|
wineventlog_security | eventtype=wineventlog_security OR Channel=security OR source=XmlWinEventLog:Security |
windows_large_number_of_computer_service_tickets_requested_filter | search * |
windows_large_number_of_computer_service_tickets_requested_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
Default Configuration
This detection is configured by default in Splunk Enterprise Security to run with the following settings:
Setting | Value |
---|---|
Disabled | true |
Cron Schedule | 0 * * * * |
Earliest Time | -70m@m |
Latest Time | -10m@m |
Schedule Window | auto |
Creates Risk Event | True |
Implementation
To successfully implement this search, you need to be ingesting Domain Controller and Kerberos events. The Advanced Security Audit policy setting Audit Kerberos Authentication Service
within Account Logon
needs to be enabled.
Known False Positives
An single endpoint requesting a large number of kerberos service tickets is not common behavior. Possible false positive scenarios include but are not limited to vulnerability scanners, administration systems and missconfigured systems.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
A large number of kerberos computer service tickets were requested by $IpAddress$ within 5 minutes. | 30 | 60 | 50 |
References
-
https://thedfirreport.com/2023/01/23/sharefinder-how-threat-actors-discover-file-shares/
-
https://learn.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4769
Detection Testing
Test Type | Status | Dataset | Source | Sourcetype |
---|---|---|---|---|
Validation | ✅ Passing | N/A | N/A | N/A |
Unit | ✅ Passing | Dataset | XmlWinEventLog:Security |
XmlWinEventLog |
Integration | ✅ Passing | Dataset | XmlWinEventLog:Security |
XmlWinEventLog |
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: GitHub | Version: 3