Sample rules
PetitPotam Suspicious Kerberos TGT Request
- source: splunk
- technicques:
- T1003
Description
The following analytic detects a suspicious Kerberos Ticket Granting Ticket (TGT) request, identified by Event Code 4768. This detection leverages Windows Security Event Logs to identify TGT requests with unusual fields, which may indicate the use of tools like Rubeus following the exploitation of CVE-2021-36942 (PetitPotam). This activity is significant as it can signal an attacker leveraging a compromised certificate to request Kerberos tickets, potentially leading to unauthorized access. If confirmed malicious, this could allow attackers to escalate privileges and persist within the environment, posing a severe security risk.
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: $