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Description

The following analytic detects a computer account requesting a Kerberos ticket, which is unusual as typically user accounts request these tickets. This detection leverages Windows Security Event Logs, specifically EventCode 4768, to identify instances where the TargetUserName ends with a dollar sign ($), indicating a computer account. This activity is significant because it may indicate the use of tools like KrbUpRelay or other Kerberos-based attacks. If confirmed malicious, this could allow attackers to impersonate computer accounts, potentially leading to unauthorized access and lateral movement within the network.

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

  • Last Updated: 2024-05-16
  • Author: Michael Haag, Splunk
  • ID: fb3b2bb3-75a4-4279-848a-165b42624770

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1558 Steal or Forge Kerberos Tickets Credential Access
Kill Chain Phase
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 10
CVE
1
2
3
4
5
`wineventlog_security`  EventCode=4768 TargetUserName="*$"  src_ip!="::1" 
| stats  count min(_time) as firstTime max(_time) as lastTime by dest, subject, action, user, TargetUserName, src_ip 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_computer_account_requesting_kerberos_ticket_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_computer_account_requesting_kerberos_ticket_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
  • dest
  • subject
  • action
  • Supplied_Realm_Name
  • user
  • Account_Name
  • src_ip

How To Implement

To successfully implement this search, you need to be ingesting Windows Security Event Logs with 4768 EventCode enabled. The Windows TA is also required.

Known False Positives

It is possible false positives will be present based on third party applications. Filtering may be needed.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
35.0 50 70 A Computer Account requested a Kerberos ticket on $dest$, possibly indicative of Kerberos relay attack.

: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: 3