Detect Steal or Forge Kerberos Tickets in CrowdStrike LogScale
Adversaries may attempt to subvert Kerberos authentication by stealing or forging Kerberos tickets to enable Pass the Ticket (T1550.003). In Active Directory environments, Kerberos is the primary authentication protocol. Adversaries exploit it through multiple sub-techniques: Kerberoasting (T1558.003) requests service tickets for accounts with SPNs using RC4 encryption for offline hash cracking; AS-REP Roasting (T1558.004) targets accounts with pre-authentication disabled to obtain crackable AS-REP responses; Golden Ticket attacks (T1558.001) use a stolen KRBTGT hash to forge TGTs granting unrestricted domain access; Silver Ticket attacks (T1558.002) forge service tickets using a service account hash for targeted service access; and Ccache file theft (T1558.005) targets Linux/macOS Kerberos credential cache files. Common offensive tools include Rubeus, Mimikatz (kerberos modules), Kekeo, and the Impacket suite (GetUserSPNs.py, GetNPUsers.py, ticketer.py). Detection leverages Windows Security Kerberos event IDs 4768, 4769, and 4771 for protocol-level anomalies such as RC4 encryption downgrade requests in AES-enforced environments, and process telemetry for offensive tool signatures.
MITRE ATT&CK
- Tactic
- Credential Access
- Technique
- T1558 Steal or Forge Kerberos Tickets
- Canonical reference
- https://attack.mitre.org/techniques/T1558/
LogScale Detection Query
// T1558: Steal or Forge Kerberos Tickets — CrowdStrike LogScale (Falcon CQL)
// Pattern 1 & 2: Kerberos protocol anomalies via Windows Security Event telemetry
// (Requires Windows Security Event log collection enabled in Falcon sensor)
#event_simpleName = "WindowsSecurityEvent"
| EventCode in (4768, 4769)
| TicketEncryptionType in ("0x17", "0x18")
| (
// Kerberoasting: RC4 service ticket for non-machine account
(
EventCode = 4769
| ServiceName != /.*\$$/
| ServiceName != /^(krbtgt|kadmin\/changepw)$/i
| ClientAddress != /^(::1|127\.0\.0\.1|-)$/
| Status = "0x0"
| AttackPattern := "Kerberoasting"
| Severity := "Critical"
)
or
// AS-REP Roasting: pre-auth disabled TGT
(
EventCode = 4768
| PreAuthType in ("0", "0x0")
| AttackPattern := "AS-REP Roasting"
| Severity := "High"
)
or
// Golden Ticket indicator: RC4 TGT
(
EventCode = 4768
| ClientAddress != /^(::1|127\.0\.0\.1|-)$/
| AttackPattern := "Potential Golden Ticket (RC4 TGT)"
| Severity := "Critical"
)
)
| table([timestamp, ComputerName, TargetUserName, ClientAddress, ServiceName, TicketEncryptionType, PreAuthType, EventCode, AttackPattern, Severity])
// Pattern 3: Kerberos attack tool process execution via Falcon EDR
| union {
#event_simpleName = ProcessRollup2
| CommandLine = /(?i)(rubeus|kerberoast|asreproast|getuserspns|getnpusers|sekurlsa::tickets|kerberos::golden|kerberos::silver|kerberos::ptt|\.kirbi|ticketer\.py|tgtdeleg|kekeo)/
OR ImageFileName = /(?i)(rubeus\.exe|kekeo\.exe)$/
| AttackPattern := "Kerberos Attack Tool"
| Severity := "Critical"
| table([timestamp, ComputerName, UserName, FileName, CommandLine, ParentBaseFileName, AttackPattern, Severity])
}
| sort(timestamp, order=desc)CrowdStrike LogScale (Falcon CQL) query detecting T1558 Steal or Forge Kerberos Tickets via two data sources: Windows Security Event telemetry (EventIDs 4768/4769) for protocol-level anomalies including Kerberoasting (RC4 TGS), AS-REP Roasting (pre-auth disabled), and Golden Ticket indicators (RC4 TGT); and Falcon EDR ProcessRollup2 events for Kerberos offensive tool detection (Rubeus, Mimikatz kerberos modules, Impacket). Uses union to combine both telemetry streams into a single prioritized output.
Data Sources
Required Tables
False Positives & Tuning
- Falcon sensors with Windows Security Event log collection disabled will only see the ProcessRollup2 tool detections, missing protocol-level patterns
- Legacy systems in the environment that still use RC4 Kerberos will generate persistent low-level noise on 4769 events with 0x17
- Automated SPN scanning by AD management tools (e.g., Microsoft ATA/Defender for Identity during initial learning phase) can resemble Kerberoasting patterns
- Authorized offensive security testing using tools like Rubeus in named red team exercises — correlate ContextProcessId with approved test timeframes
Other platforms for T1558
Testing Methodology
Validate this detection against 5 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 1Kerberoasting with Rubeus — RC4 TGS Enumeration
Expected signal: Sysmon Event ID 1: Process Create with Image ending in Rubeus.exe and CommandLine containing 'kerberoast'. Windows Security Event ID 4769 on the domain controller for each SPN enumerated, with TicketEncryptionType=0x17 and TicketOptions=0x40810000. The requesting AccountName and source IpAddress will match the test machine. Multiple 4769 events in rapid succession from the same source IP is the key burst pattern.
- Test 2AS-REP Roasting with Rubeus — Pre-Auth Disabled Account Hash Capture
Expected signal: Sysmon Event ID 1: Process Create with Image ending in Rubeus.exe and CommandLine containing 'asreproast'. Windows Security Event ID 4768 on the domain controller for each targeted account, with PreAuthType=0 and TicketEncryptionType=0x17 or 0x18. Source IpAddress matches test machine.
- Test 3Kerberos Ticket Dump with Mimikatz
Expected signal: Sysmon Event ID 1: Process Create with Image ending in mimikatz.exe and CommandLine containing 'sekurlsa::tickets'. Sysmon Event ID 10 (Process Access): mimikatz.exe accessing lsass.exe with GrantedAccess 0x1010 or 0x1438. Sysmon Event ID 11 (File Create): multiple .kirbi files written to the working directory. Windows Defender Event ID 1116 may fire on AMSI or signature detection.
- Test 4AS-REP Roasting with Impacket GetNPUsers.py (Linux/Cross-Platform)
Expected signal: Windows Security Event ID 4768 on the targeted domain controller for each AS-REP Roastable account, with PreAuthType=0 and source IpAddress matching the Linux attacker machine. On the DC Sysmon would not capture this (it's a network event), so primary telemetry is the Security log. DNS/LDAP queries to the DC LDAP port (389/636) from the source IP visible in network logs.
- Test 5Kerberos Ticket Enumeration with Built-in klist
Expected signal: Sysmon Event ID 1: Process Create with Image = C:\Windows\System32\klist.exe. Security Event ID 4688 (if command line auditing enabled) with ProcessName = klist.exe. No 4769 events are generated — klist reads from local cache only without contacting the KDC.
References (13)
- https://attack.mitre.org/techniques/T1558/
- https://adsecurity.org/?p=1515
- https://adsecurity.org/?p=2293
- https://adsecurity.org/?p=227
- https://blog.stealthbits.com/detect-pass-the-ticket-attacks
- https://blogs.technet.microsoft.com/motiba/2018/02/23/detecting-kerberoasting-activity-using-azure-security-center/
- https://cert.europa.eu/static/WhitePapers/UPDATED%20-%20CERT-EU_Security_Whitepaper_2014-007_Kerberos_Golden_Ticket_Protection_v1_4.pdf
- https://docs.microsoft.com/windows-server/administration/windows-commands/klist
- https://github.com/GhostPack/Rubeus
- https://github.com/SecureAuthCorp/impacket
- https://medium.com/threatpunter/detecting-attempts-to-steal-passwords-from-memory-558f16dce4ea
- https://learn.microsoft.com/en-us/defender-endpoint/advanced-hunting-deviceprocessevents-table
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1558/T1558.md
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