Password spray attack against Microsoft Entra ID Seamless SSO

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Id	fb7ca1c9-e14c-40a3-856e-28f3c14ea1ba
Rulename	Password spray attack against Microsoft Entra ID Seamless SSO
Description	This query detects when there is a spike in Microsoft Entra ID Seamless SSO errors. They may not be caused by a Password Spray attack, but the cause of the errors might need to be investigated. Microsoft Entra ID only logs the requests that matched existing accounts, thus there might have been unlogged requests for non-existing accounts.
Severity	Medium
Tactics	CredentialAccess
Techniques	T1110
Required data connectors	AzureActiveDirectory
Kind	Scheduled
Query frequency	1h
Query period	1h
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Entra ID/Analytic Rules/SeamlessSSOPasswordSpray.yaml
Version	1.0.4
Arm template	fb7ca1c9-e14c-40a3-856e-28f3c14ea1ba.json

KQL

let account_threshold = 5;
AADNonInteractiveUserSignInLogs
//| where ResultType == "81016"
| where ResultType startswith "81"
| summarize DistinctAccounts = dcount(UserPrincipalName), DistinctAddresses = make_set(IPAddress,100) by ResultType
| where DistinctAccounts > account_threshold
| mv-expand IPAddress = DistinctAddresses
| extend IPAddress = tostring(IPAddress)
| join kind=leftouter (union isfuzzy=true SigninLogs, AADNonInteractiveUserSignInLogs) on IPAddress
| summarize
    StartTime = min(TimeGenerated),
    EndTime = max(TimeGenerated),
    UserPrincipalName = make_set(UserPrincipalName,100),
    UserAgent = make_set(UserAgent,100),
    ResultDescription = take_any(ResultDescription),
    ResultSignature = take_any(ResultSignature)
    by IPAddress, Type, ResultType
| project Type, StartTime, EndTime, IPAddress, ResultType, ResultDescription, ResultSignature, UserPrincipalName, UserAgent = iff(array_length(UserAgent) == 1, UserAgent[0], UserAgent)
| extend Name = tostring(split(UserPrincipalName[0],'@',0)[0]), UPNSuffix = tostring(split(UserPrincipalName[0],'@',1)[0])

YAML

triggerOperator: gt
queryFrequency: 1h
description: |
  'This query detects when there is a spike in Microsoft Entra ID Seamless SSO errors. They may not be caused by a Password Spray attack, but the cause of the errors might need to be investigated.
  Microsoft Entra ID only logs the requests that matched existing accounts, thus there might have been unlogged requests for non-existing accounts.'  
status: Available
kind: Scheduled
triggerThreshold: 0
requiredDataConnectors:
- connectorId: AzureActiveDirectory
  dataTypes:
  - AADNonInteractiveUserSignInLogs
version: 1.0.4
queryPeriod: 1h
name: Password spray attack against Microsoft Entra ID Seamless SSO
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Entra ID/Analytic Rules/SeamlessSSOPasswordSpray.yaml
id: fb7ca1c9-e14c-40a3-856e-28f3c14ea1ba
tactics:
- CredentialAccess
relevantTechniques:
- T1110
severity: Medium
entityMappings:
- fieldMappings:
  - identifier: FullName
    columnName: UserPrincipalName
  - identifier: Name
    columnName: Name
  - identifier: UPNSuffix
    columnName: UPNSuffix
  entityType: Account
- fieldMappings:
  - identifier: Address
    columnName: IPAddress
  entityType: IP
query: |
  let account_threshold = 5;
  AADNonInteractiveUserSignInLogs
  //| where ResultType == "81016"
  | where ResultType startswith "81"
  | summarize DistinctAccounts = dcount(UserPrincipalName), DistinctAddresses = make_set(IPAddress,100) by ResultType
  | where DistinctAccounts > account_threshold
  | mv-expand IPAddress = DistinctAddresses
  | extend IPAddress = tostring(IPAddress)
  | join kind=leftouter (union isfuzzy=true SigninLogs, AADNonInteractiveUserSignInLogs) on IPAddress
  | summarize
      StartTime = min(TimeGenerated),
      EndTime = max(TimeGenerated),
      UserPrincipalName = make_set(UserPrincipalName,100),
      UserAgent = make_set(UserAgent,100),
      ResultDescription = take_any(ResultDescription),
      ResultSignature = take_any(ResultSignature)
      by IPAddress, Type, ResultType
  | project Type, StartTime, EndTime, IPAddress, ResultType, ResultDescription, ResultSignature, UserPrincipalName, UserAgent = iff(array_length(UserAgent) == 1, UserAgent[0], UserAgent)
  | extend Name = tostring(split(UserPrincipalName[0],'@',0)[0]), UPNSuffix = tostring(split(UserPrincipalName[0],'@',1)[0])

ARM

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2023-02-01-preview",
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/fb7ca1c9-e14c-40a3-856e-28f3c14ea1ba')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/fb7ca1c9-e14c-40a3-856e-28f3c14ea1ba')]",
      "properties": {
        "alertRuleTemplateName": "fb7ca1c9-e14c-40a3-856e-28f3c14ea1ba",
        "customDetails": null,
        "description": "'This query detects when there is a spike in Microsoft Entra ID Seamless SSO errors. They may not be caused by a Password Spray attack, but the cause of the errors might need to be investigated.\nMicrosoft Entra ID only logs the requests that matched existing accounts, thus there might have been unlogged requests for non-existing accounts.'\n",
        "displayName": "Password spray attack against Microsoft Entra ID Seamless SSO",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "UserPrincipalName",
                "identifier": "FullName"
              },
              {
                "columnName": "Name",
                "identifier": "Name"
              },
              {
                "columnName": "UPNSuffix",
                "identifier": "UPNSuffix"
              }
            ]
          },
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "IPAddress",
                "identifier": "Address"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Entra ID/Analytic Rules/SeamlessSSOPasswordSpray.yaml",
        "query": "let account_threshold = 5;\nAADNonInteractiveUserSignInLogs\n//| where ResultType == \"81016\"\n| where ResultType startswith \"81\"\n| summarize DistinctAccounts = dcount(UserPrincipalName), DistinctAddresses = make_set(IPAddress,100) by ResultType\n| where DistinctAccounts > account_threshold\n| mv-expand IPAddress = DistinctAddresses\n| extend IPAddress = tostring(IPAddress)\n| join kind=leftouter (union isfuzzy=true SigninLogs, AADNonInteractiveUserSignInLogs) on IPAddress\n| summarize\n    StartTime = min(TimeGenerated),\n    EndTime = max(TimeGenerated),\n    UserPrincipalName = make_set(UserPrincipalName,100),\n    UserAgent = make_set(UserAgent,100),\n    ResultDescription = take_any(ResultDescription),\n    ResultSignature = take_any(ResultSignature)\n    by IPAddress, Type, ResultType\n| project Type, StartTime, EndTime, IPAddress, ResultType, ResultDescription, ResultSignature, UserPrincipalName, UserAgent = iff(array_length(UserAgent) == 1, UserAgent[0], UserAgent)\n| extend Name = tostring(split(UserPrincipalName[0],'@',0)[0]), UPNSuffix = tostring(split(UserPrincipalName[0],'@',1)[0])\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "Medium",
        "status": "Available",
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "CredentialAccess"
        ],
        "techniques": [
          "T1110"
        ],
        "templateVersion": "1.0.4",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}