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Description

The following analytic detects a process accessing the winlogon.exe system process, indicative of the Rubeus tool attempting to export Kerberos tickets from memory. This detection leverages Sysmon EventCode 10 logs, focusing on processes obtaining a handle to winlogon.exe with specific access rights. This activity is significant as it often precedes pass-the-ticket attacks, where adversaries use stolen Kerberos tickets to move laterally within an environment. If confirmed malicious, this could allow attackers to bypass normal access controls, escalate privileges, and persist within the network, posing a severe security risk.

  • Type: TTP

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

  • Last Updated: 2024-05-27
  • Author: Mauricio Velazco, Splunk
  • ID: 5ed8c50a-8869-11ec-876f-acde48001122

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1550 Use Alternate Authentication Material Defense Evasion, Lateral Movement
T1550.003 Pass the Ticket Defense Evasion, Lateral Movement
Kill Chain Phase
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


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 `sysmon` EventCode=10 TargetImage=C:\\Windows\\system32\\winlogon.exe (GrantedAccess=0x1f3fff) (SourceImage!=C:\\Windows\\system32\\svchost.exe AND SourceImage!=C:\\Windows\\system32\\lsass.exe AND SourceImage!=C:\\Windows\\system32\\LogonUI.exe AND SourceImage!=C:\\Windows\\system32\\smss.exe AND SourceImage!=C:\\Windows\\system32\\wbem\\wmiprvse.exe) 
| stats count min(_time) as firstTime max(_time) as lastTime by dest, SourceImage, SourceProcessId, TargetImage, TargetProcessId, EventCode, GrantedAccess  
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)` 
| `rubeus_kerberos_ticket_exports_through_winlogon_access_filter`

Macros

The SPL above uses the following Macros:

:information_source: rubeus_kerberos_ticket_exports_through_winlogon_access_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
  • TargetImage
  • CallTrace
  • dest
  • TargetProcessId
  • SourceImage
  • SourceProcessId

How To Implement

This search needs Sysmon Logs and a sysmon configuration, which includes EventCode 10. This search uses an input macro named sysmon. We strongly recommend that you specify your environment-specific configurations (index, source, sourcetype, etc.) for Windows Sysmon logs. Replace the macro definition with configurations for your Splunk environment.

Known False Positives

Legitimate applications may obtain a handle for winlogon.exe. Filter as needed

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
36.0 60 60 Winlogon.exe was accessed by $SourceImage$ on $dest$

:information_source: 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

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: 2