Microsoft Sentinel medium experimental kql

NRT First access credential added to Application or Service Principal where no credential was present

'This will alert when an admin or app owner account adds a new credential to an Application or Service Principal where there was no previous verify KeyCredential associated. If a threat actor obtains access to an account with sufficient privileges and adds the alternate authentication material triggering this event, the threat actor can now authenticate as the Application or Service Principal using this credential. Additional information on OAuth Credential Grants can be found in RFC 6749 Section 4.4 or https://docs.microsoft.com/azure/active-directory/develop/v2-oauth2-client-creds-grant-flow For further information on AuditLogs please see https://docs.microsoft.com/azure/active-directory/reports-monitoring/reference-audit-activities.'

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Detection Logic

AuditLogs
| where OperationName has_any ("Add service principal", "Certificates and secrets management")
| where Result =~ "success"
| where tostring(InitiatedBy.user.userPrincipalName) has "@" or tostring(InitiatedBy.app.displayName) has "@"
| mv-apply TargetResource = TargetResources on 
  (
    where TargetResource.type =~ "Application"
| extend targetDisplayName = tostring(TargetResource.displayName),
             targetId = tostring(TargetResource.id),
             targetType = tostring(TargetResource.type),
             keyEvents = TargetResource.modifiedProperties
  )
| mv-apply Property = keyEvents on 
 (
  where Property.displayName =~ "KeyDescription"
| extend new_value_set = parse_json(tostring(Property.newValue)),
           old_value_set = parse_json(tostring(Property.oldValue))
 )
| where old_value_set == "[]"
| mv-expand new_value_set
| parse new_value_set with * "KeyIdentifier=" keyIdentifier:string ",KeyType=" keyType:string ",KeyUsage=" keyUsage:string ",DisplayName=" keyDisplayName:string "]" *
| where keyUsage == "Verify"
| mv-apply AdditionalDetail = AdditionalDetails on 
  (
    where AdditionalDetail.key =~ "User-Agent"
| extend UserAgent = tostring(AdditionalDetail.value)
  )
| extend InitiatingAppName = tostring(InitiatedBy.app.displayName)
| extend InitiatingAppServicePrincipalId = tostring(InitiatedBy.app.servicePrincipalId)
| extend InitiatingUserPrincipalName = tostring(InitiatedBy.user.userPrincipalName)
| extend InitiatingAadUserId = tostring(InitiatedBy.user.id)
| extend InitiatingIpAddress = tostring(iff(isnotempty(InitiatedBy.user.ipAddress), InitiatedBy.user.ipAddress, InitiatedBy.app.ipAddress))
//
| where targetType =~ "Application" // or targetType =~ "ServicePrincipal"
| project-away new_value_set, old_value_set
| project-reorder TimeGenerated, OperationName, InitiatingUserPrincipalName, InitiatingAadUserId, InitiatingAppName, InitiatingAppServicePrincipalId, InitiatingIpAddress, UserAgent, targetDisplayName, targetId, targetType, keyDisplayName, keyType, keyUsage, keyIdentifier, CorrelationId, TenantId
| extend InitiatedByName = tostring(split(InitiatingUserPrincipalName,'@',0)[0]), InitiatedByUPNSuffix = tostring(split(InitiatingUserPrincipalName,'@',1)[0])

Field Validations

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