Sample rules
PetitPotam Suspicious Kerberos TGT Request
- source: splunk
- technicques:
- T1003
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.
Detection logic
`wineventlog_security` EventCode=4768 src!="::1" TargetUserName=*$ CertThumbprint!=""
| stats count min(_time) as firstTime max(_time) as lastTime by dest, TargetUserName, src, action
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `petitpotam_suspicious_kerberos_tgt_request_filter`
PetitPotam Suspicious Kerberos TGT Request
- source: sigma
- technicques:
- t1187
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.
Detection logic
condition: selection and not 1 of filter_*
filter_local:
IpAddress: ::1
filter_thumbprint:
CertThumbprint: ''
selection:
CertThumbprint|contains: '*'
EventID: 4768
TargetUserName|endswith: $