Detect Kerberoasting in Sumo Logic CSE
Adversaries may abuse a valid Kerberos ticket-granting ticket (TGT) to request Kerberos ticket-granting service (TGS) tickets for any service principal name (SPN) registered in Active Directory. Portions of these tickets encrypted with RC4 (etype 0x17) use the service account's NTLM hash as the private key, making them vulnerable to offline brute force attacks using tools like Hashcat or John the Ripper. Cracked credentials enable persistence, privilege escalation, and lateral movement via valid domain accounts. Common tooling includes Rubeus, Invoke-Kerberoast (PowerSploit/Empire), Impacket GetUserSPNs.py, SILENTTRINITY, and Brute Ratel C4. Confirmed threat actor usage includes Wizard Spider (Ryuk ransomware campaigns), FIN7, and Indrik Spider.
MITRE ATT&CK
- Tactic
- Credential Access
- Technique
- T1558 Steal or Forge Kerberos Tickets
- Sub-technique
- T1558.003 Kerberoasting
- Canonical reference
- https://attack.mitre.org/techniques/T1558/003/
Sumo Detection Query
_sourceCategory=Windows/Security EventCode=4769
| json "TargetUserName" as TargetUserName nodrop
| json "ServiceName" as ServiceName nodrop
| json "TicketEncryptionType" as TicketEncryptionType nodrop
| json "IpAddress" as IpAddress nodrop
| where !isNull(TargetUserName) and !isNull(TicketEncryptionType)
| where TicketEncryptionType = "0x17"
| where !(TargetUserName matches "*$")
| where !(ServiceName matches "*$")
| where ServiceName != "krbtgt"
| replace(IpAddress, "::ffff:", "") as NormalizedSourceIP
| timeslice 1h
| count_distinct(ServiceName) as UniqueServiceCount, count as TGSRequestCount by TargetUserName, NormalizedSourceIP, _sourceHost, _timeslice
| where UniqueServiceCount >= 1
| if(UniqueServiceCount >= 5, "true", "false") as IsBulkKerberoast
| if(UniqueServiceCount >= 20, "Critical", if(UniqueServiceCount >= 5, "High", "Medium")) as AlertPriority
| fields - _timeslice
| sort by UniqueServiceCount desc, TGSRequestCount descSumo Logic query detecting Kerberoasting via RC4-encrypted Kerberos TGS requests (Event 4769, etype 0x17). Parses JSON-structured Windows Security event fields produced by the Sumo Logic Installed Collector with JSON output mode enabled on the Windows Event Source. Normalizes IPv4-mapped IPv6 addresses, aggregates unique SPN counts per user/source-IP/host over 1-hour timeslices, and classifies alert priority by SPN enumeration volume. Adjust _sourceCategory to match your collector configuration.
Data Sources
Required Tables
False Positives & Tuning
- Service accounts belonging to backup, replication, or orchestration platforms (e.g. Veeam, Commvault, Ansible Tower) that authenticate to multiple server SPNs using RC4 Kerberos during scheduled job windows
- IT automation platforms or configuration management systems using a centralized service account that authenticates to many managed endpoints in rapid sequence during deployment or compliance runs
- Domain-joined middleware or application servers (e.g. JBoss, WebLogic, older JDBC connectors) that do not support AES Kerberos and default to RC4 cipher when authenticating to database or messaging service SPNs
Other platforms for T1558.003
Testing Methodology
Validate this detection against 4 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Invoke-Kerberoast via PowerSploit — Bulk Hash Extraction
Expected signal: Domain Controller Security Event ID 4769 for each SPN enumerated with TicketEncryptionType=0x17. Sysmon Event ID 1 on source host: powershell.exe with 'Invoke-Kerberoast' in CommandLine. Sysmon Event ID 3: TCP connection to DC on port 88 (Kerberos). PowerShell ScriptBlock Event ID 4104 with full Invoke-Kerberoast script content (deobfuscated). Sysmon Event ID 11: file creation for kerberoast_hashes.txt.
- Test 2Rubeus Kerberoast — All Roastable Accounts
Expected signal: Domain Controller Security Event ID 4769 for each SPN with TicketEncryptionType=0x17. Sysmon Event ID 1: Rubeus.exe process creation with 'kerberoast' argument. Sysmon Event ID 3: TCP connection to DC on port 88. Sysmon Event ID 11: file creation for rubeus_hashes.txt. Windows Defender may independently generate alerts for Rubeus.exe based on signature detection.
- Test 3Impacket GetUserSPNs — Linux-Based Kerberoasting
Expected signal: Domain Controller Security Event ID 4769 for each SPN with TicketEncryptionType=0x17, IpAddress field contains the Linux host IP. Event ID 4768 (TGT request) from Linux host IP preceding the 4769 events. No Sysmon telemetry (Linux source). DC Security logs capture the full activity. The source IP not matching any domain-joined Windows workstation is a high-fidelity anomaly indicator.
- Test 4Targeted Single-SPN Request via .NET KerberosRequestorSecurityToken
Expected signal: Domain Controller Security Event ID 4769: ServiceName=MSSQLSvc/sql01.corp.local:1433, TicketEncryptionType=0x17 (if target service account supports RC4). Sysmon Event ID 1: powershell.exe with 'KerberosRequestorSecurityToken' in CommandLine. PowerShell ScriptBlock Event ID 4104 with full .NET reflection code. Note: If the target account enforces AES-only encryption, EncryptionType will be 0x12 and detection will not fire on the RC4 rule — the account is not kerberoastable.
References (10)
- https://attack.mitre.org/techniques/T1558/003/
- https://blogs.technet.microsoft.com/motiba/2018/02/23/detecting-kerberoasting-activity-using-azure-security-center/
- https://adsecurity.org/?p=2293
- https://blog.harmj0y.net/powershell/kerberoasting-without-mimikatz/
- https://github.com/GhostPack/Rubeus
- https://github.com/fortra/impacket/blob/master/examples/GetUserSPNs.py
- https://learn.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4769
- https://redsiege.com/kerberoast-slides
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1558.003/T1558.003.md
- https://www.crowdstrike.com/blog/meet-carbon-spider/
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