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Description

The following analytic looks for a process accessing the winlogon.exe system process. The Splunk Threat Research team identified this behavior when using the Rubeus tool to monitor for and export kerberos tickets from memory. Before being able to export tickets. Rubeus will try to escalate privileges to SYSTEM by obtaining a handle to winlogon.exe before trying to monitor for kerberos tickets. Exporting tickets from memory is typically the first step for pass the ticket attacks. Red teams and adversaries alike may use the pass the ticket technique using stolen Kerberos tickets to move laterally within an environment, bypassing normal system access controls. Defenders should be aware that adversaries may customize the source code of Rubeus to potentially bypass this analytic.

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

  • Last Updated: 2022-02-07
  • 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
CIS20
CVE
1
2
3
4
5
6
 `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 Computer, SourceImage, SourceProcessId, TargetImage, TargetProcessId, EventCode, GrantedAccess 
| rename Computer as dest 
| `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
  • Computer
  • 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: 1