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Description

The following analytic identifes Event Code 4768, A Kerberos authentication ticket (TGT) was requested, successfull occurs. This behavior has been identified to assist with detecting PetitPotam, CVE-2021-36942. Once an attacer obtains a computer certificate by abusing Active Directory Certificate Services in combination with PetitPotam, the next step would be to leverage the certificate for malicious purposes. One way of doing this is to request a Kerberos Ticket Granting Ticket using a tool like Rubeus. This request will generate a 4768 event with some unusual fields depending on the environment. This analytic will require tuning, we recommend filtering Account_Name to Domain Controllers for your environment.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel:
  • Last Updated: 2021-08-31
  • Author: Michael Haag, Mauricio Velazco, Splunk
  • ID: e3ef244e-0a67-11ec-abf2-acde48001122

ATT&CK

ID Technique Tactic
T1003 OS Credential Dumping Credential Access
`wineventlog_security` EventCode=4768 Client_Address!="::1" Certificate_Thumbprint!="" Account_Name=*$ 
| stats count min(_time) as firstTime max(_time) as lastTime by dest, Account_Name, Client_Address, action, Message 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `petitpotam_suspicious_kerberos_tgt_request_filter`

Associated Analytic Story

How To Implement

The following analytic requires Event Code 4768. Ensure that it is logging no Domain Controllers and appearing in Splunk.

Required field

  • _time
  • dest
  • Account_Name
  • Client_Address
  • action
  • Message

Kill Chain Phase

  • Exploitation
  • Lateral Movement

Known False Positives

False positives are possible if the environment is using certificates for authentication.

RBA

Risk Score Impact Confidence Message
56.0 80 70 A Kerberos TGT was requested in a non-standard manner against $dest$, potentially related to CVE-2021-36942, PetitPotam.

CVE

ID Summary CVSS
CVE-2021-36942 Windows LSA Spoofing Vulnerability 5.0

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

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