Potential Kerberoasting

Requête originale, sans modification.

let starttime = 1d;
let endtime = 1h;
let prev23hThreshold = 4;
let prev1hThreshold = 15;
let Kerbevent = (union isfuzzy=true
(SecurityEvent
| where TimeGenerated >= ago(starttime)
| where EventID == 4769
| parse EventData with * 'TicketEncryptionType">' TicketEncryptionType "<" *
| where TicketEncryptionType == '0x17'
| parse EventData with * 'TicketOptions">' TicketOptions "<" *
| where TicketOptions == '0x40810000'
| parse EventData with * 'Status">' Status "<" *
| where Status == '0x0'
| parse EventData with * 'ServiceName">' ServiceName "<" *
| where ServiceName !contains "$" and ServiceName !contains "krbtgt"
| parse EventData with * 'TargetUserName">' TargetUserName "<" *
| where TargetUserName !contains "$@" and TargetUserName !contains ServiceName
| parse EventData with * 'IpAddress">::ffff:' ClientIPAddress "<" *
),
(
WindowsEvent
| where TimeGenerated >= ago(starttime)
| where EventID == 4769 and EventData has '0x17' and EventData has '0x40810000' and EventData has 'krbtgt'
| extend TicketEncryptionType = tostring(EventData.TicketEncryptionType)
| where TicketEncryptionType == '0x17'
| extend TicketOptions = tostring(EventData.TicketOptions)
| where TicketOptions == '0x40810000'
| extend Status = tostring(EventData.Status)
| where Status == '0x0'
| extend ServiceName = tostring(EventData.ServiceName)
| where ServiceName !contains "$" and ServiceName !contains "krbtgt"
| extend TargetUserName = tostring(EventData.TargetUserName)
| where TargetUserName !contains "$@" and TargetUserName !contains ServiceName
| extend ClientIPAddress = tostring(EventData.IpAddress)
));
let Kerbevent23h = Kerbevent
| where TimeGenerated >= ago(starttime) and TimeGenerated < ago(endtime)
| summarize ServiceNameCountPrev23h = dcount(ServiceName), ServiceNameSet23h = makeset(ServiceName)
by Computer, TargetUserName,TargetDomainName, ClientIPAddress, TicketOptions, TicketEncryptionType, Status
| where ServiceNameCountPrev23h < prev23hThreshold;
let Kerbevent1h =
Kerbevent
| where TimeGenerated >= ago(endtime)
| summarize min(TimeGenerated), max(TimeGenerated), ServiceNameCountPrev1h = dcount(ServiceName), ServiceNameSet1h = makeset(ServiceName)
by Computer, TargetUserName, TargetDomainName, ClientIPAddress, TicketOptions, TicketEncryptionType, Status;
Kerbevent1h
| join kind=leftanti
(
Kerbevent23h
) on TargetUserName, TargetDomainName
// Threshold value set above is based on testing, this value may need to be changed for your environment.
| where ServiceNameCountPrev1h > prev1hThreshold
| project StartTime = min_TimeGenerated, EndTime = max_TimeGenerated, TargetUserName, Computer, ClientIPAddress, TicketOptions,
TicketEncryptionType, Status, ServiceNameCountPrev1h, ServiceNameSet1h, TargetDomainName
| extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
| extend TargetAccount = strcat(TargetDomainName,  "\\", TargetUserName)
| project-away DomainIndex