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PetitPotam Suspicious Kerberos TGT Request

Detect suspicious Kerberos TGT requests. 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 the Domain Controller computer accounts.

MITRE ATT&CK

T1187

credential-access

Detection Query

selection:
  EventID: 4768
  TargetUserName|endswith: $
  CertThumbprint|contains: "*"
filter_local:
  IpAddress: ::1
filter_thumbprint:
  CertThumbprint: ""
condition: selection and not 1 of filter_*

Author

Mauricio Velazco, Michael Haag

Created

2021-09-02

Data Sources

windowssecurity

Platforms

windows

References

Tags

attack.credential-accessattack.t1187

Raw Content

title: PetitPotam Suspicious Kerberos TGT Request
id: 6a53d871-682d-40b6-83e0-b7c1a6c4e3a5
status: test
description: |
    Detect suspicious Kerberos TGT requests.
    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 the Domain Controller computer accounts.
references:
    - https://github.com/topotam/PetitPotam
    - https://isc.sans.edu/forums/diary/Active+Directory+Certificate+Services+ADCS+PKI+domain+admin+vulnerability/27668/
    - https://github.com/splunk/security_content/blob/88d689fe8a055d8284337b9fad5d9152b42043db/detections/endpoint/petitpotam_suspicious_kerberos_tgt_request.yml
author: Mauricio Velazco, Michael Haag
date: 2021-09-02
modified: 2022-10-05
tags:
    - attack.credential-access
    - attack.t1187
logsource:
    product: windows
    service: security
    definition: 'The advanced audit policy setting "Account Logon > Kerberos Authentication Service" must be configured for Success/Failure'
detection:
    selection:
        EventID: 4768
        TargetUserName|endswith: '$'
        CertThumbprint|contains: '*'
    filter_local:
        IpAddress: '::1'
    filter_thumbprint:
        CertThumbprint: ''
    condition: selection and not 1 of filter_*
falsepositives:
    - False positives are possible if the environment is using certificates for authentication. We recommend filtering Account_Name to the Domain Controller computer accounts.
level: high