Microsoft Sentinel Analytic Rules
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Brute force attack against a Cloud PC

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Id3fbc20a4-04c4-464e-8fcb-6667f53e4987
RulenameBrute force attack against a Cloud PC
DescriptionIdentifies evidence of brute force activity against a Windows 365 Cloud PC by highlighting multiple authentication failures and by a successful authentication within a given time window.
SeverityMedium
TacticsCredentialAccess
TechniquesT1110
Required data connectorsAzureActiveDirectory
KindScheduled
Query frequency1d
Query period1d
Trigger threshold0
Trigger operatorgt
Source Urihttps://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Entra ID/Analytic Rules/BruteForceCloudPC.yaml
Version2.0.1
Arm template3fbc20a4-04c4-464e-8fcb-6667f53e4987.json
Deploy To Azure
let authenticationWindow = 20m;
let sensitivity = 2.5;
SigninLogs
| where AppDisplayName =~ "Windows Sign In"
| extend FailureOrSuccess = iff(ResultType in ("0", "50125", "50140", "70043", "70044"), "Success", "Failure")
| summarize FailureCount = countif(FailureOrSuccess=="Failure"), SuccessCount = countif(FailureOrSuccess=="Success"), IPAddresses = make_set(IPAddress,1000)
                          by bin(TimeGenerated, authenticationWindow), UserDisplayName, UserPrincipalName
| extend FailureSuccessDiff = FailureCount - SuccessCount
| where FailureSuccessDiff > 0
| summarize Diff = make_list(FailureSuccessDiff, 10000), TimeStamp = make_list(TimeGenerated, 10000) by UserDisplayName, UserPrincipalName//, tostring(IPAddresses)
| extend (Anomalies, Score, Baseline) = series_decompose_anomalies(Diff, sensitivity, -1, 'linefit')  
| mv-expand Diff to typeof(double), TimeStamp to typeof(datetime), Anomalies to typeof(double), Score to typeof(double), Baseline to typeof(long)
| where Anomalies > 0
| summarize by UserDisplayName, UserPrincipalName, Anomalies, Score, Baseline, FailureToSuccessDiff = Diff
| join kind=leftouter (
      SigninLogs
      | where AppDisplayName =~ "Windows Sign In"
      | extend OS = DeviceDetail.operatingSystem, Browser = DeviceDetail.browser
      | extend StatusCode = tostring(Status.errorCode), StatusDetails = tostring(Status.additionalDetails)
      | extend State = tostring(LocationDetails.state), City = tostring(LocationDetails.city)
      | summarize StartTime = min(TimeGenerated), 
                  EndTime = max(TimeGenerated), 
                  IPAddresses = make_set(IPAddress,100), 
                  OS = make_set(OS,20), 
                  Browser = make_set(Browser,20), 
                  City = make_set(City,100), 
                  ResultType = make_set(ResultType,100)
              by UserDisplayName, UserPrincipalName, UserId, AppDisplayName
  ) on UserDisplayName, UserPrincipalName
| project-away UserDisplayName1, UserPrincipalName1
| extend IPAddressFirst = tostring(IPAddresses[0])
| extend Name = tostring(split(UserPrincipalName,'@',0)[0]), UPNSuffix = tostring(split(UserPrincipalName,'@',1)[0])
id: 3fbc20a4-04c4-464e-8fcb-6667f53e4987
name: Brute force attack against a Cloud PC
triggerOperator: gt
status: Available
query: |
  let authenticationWindow = 20m;
  let sensitivity = 2.5;
  SigninLogs
  | where AppDisplayName =~ "Windows Sign In"
  | extend FailureOrSuccess = iff(ResultType in ("0", "50125", "50140", "70043", "70044"), "Success", "Failure")
  | summarize FailureCount = countif(FailureOrSuccess=="Failure"), SuccessCount = countif(FailureOrSuccess=="Success"), IPAddresses = make_set(IPAddress,1000)
                            by bin(TimeGenerated, authenticationWindow), UserDisplayName, UserPrincipalName
  | extend FailureSuccessDiff = FailureCount - SuccessCount
  | where FailureSuccessDiff > 0
  | summarize Diff = make_list(FailureSuccessDiff, 10000), TimeStamp = make_list(TimeGenerated, 10000) by UserDisplayName, UserPrincipalName//, tostring(IPAddresses)
  | extend (Anomalies, Score, Baseline) = series_decompose_anomalies(Diff, sensitivity, -1, 'linefit')  
  | mv-expand Diff to typeof(double), TimeStamp to typeof(datetime), Anomalies to typeof(double), Score to typeof(double), Baseline to typeof(long)
  | where Anomalies > 0
  | summarize by UserDisplayName, UserPrincipalName, Anomalies, Score, Baseline, FailureToSuccessDiff = Diff
  | join kind=leftouter (
        SigninLogs
        | where AppDisplayName =~ "Windows Sign In"
        | extend OS = DeviceDetail.operatingSystem, Browser = DeviceDetail.browser
        | extend StatusCode = tostring(Status.errorCode), StatusDetails = tostring(Status.additionalDetails)
        | extend State = tostring(LocationDetails.state), City = tostring(LocationDetails.city)
        | summarize StartTime = min(TimeGenerated), 
                    EndTime = max(TimeGenerated), 
                    IPAddresses = make_set(IPAddress,100), 
                    OS = make_set(OS,20), 
                    Browser = make_set(Browser,20), 
                    City = make_set(City,100), 
                    ResultType = make_set(ResultType,100)
                by UserDisplayName, UserPrincipalName, UserId, AppDisplayName
    ) on UserDisplayName, UserPrincipalName
  | project-away UserDisplayName1, UserPrincipalName1
  | extend IPAddressFirst = tostring(IPAddresses[0])
  | extend Name = tostring(split(UserPrincipalName,'@',0)[0]), UPNSuffix = tostring(split(UserPrincipalName,'@',1)[0])  
queryPeriod: 1d
requiredDataConnectors:
- connectorId: AzureActiveDirectory
  dataTypes:
  - SigninLogs
severity: Medium
queryFrequency: 1d
relevantTechniques:
- T1110
version: 2.0.1
kind: Scheduled
tactics:
- CredentialAccess
triggerThreshold: 0
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Entra ID/Analytic Rules/BruteForceCloudPC.yaml
entityMappings:
- fieldMappings:
  - identifier: FullName
    columnName: UserPrincipalName
  - identifier: Name
    columnName: Name
  - identifier: UPNSuffix
    columnName: UPNSuffix
  entityType: Account
- fieldMappings:
  - identifier: AadUserId
    columnName: UserId
  entityType: Account
- fieldMappings:
  - identifier: Address
    columnName: IPAddressFirst
  entityType: IP
description: |
    'Identifies evidence of brute force activity against a Windows 365 Cloud PC by highlighting multiple authentication failures and by a successful authentication within a given time window.'
{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2024-01-01-preview",
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/3fbc20a4-04c4-464e-8fcb-6667f53e4987')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/3fbc20a4-04c4-464e-8fcb-6667f53e4987')]",
      "properties": {
        "alertRuleTemplateName": "3fbc20a4-04c4-464e-8fcb-6667f53e4987",
        "customDetails": null,
        "description": "'Identifies evidence of brute force activity against a Windows 365 Cloud PC by highlighting multiple authentication failures and by a successful authentication within a given time window.'\n",
        "displayName": "Brute force attack against a Cloud PC",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "UserPrincipalName",
                "identifier": "FullName"
              },
              {
                "columnName": "Name",
                "identifier": "Name"
              },
              {
                "columnName": "UPNSuffix",
                "identifier": "UPNSuffix"
              }
            ]
          },
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "UserId",
                "identifier": "AadUserId"
              }
            ]
          },
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "IPAddressFirst",
                "identifier": "Address"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Entra ID/Analytic Rules/BruteForceCloudPC.yaml",
        "query": "let authenticationWindow = 20m;\nlet sensitivity = 2.5;\nSigninLogs\n| where AppDisplayName =~ \"Windows Sign In\"\n| extend FailureOrSuccess = iff(ResultType in (\"0\", \"50125\", \"50140\", \"70043\", \"70044\"), \"Success\", \"Failure\")\n| summarize FailureCount = countif(FailureOrSuccess==\"Failure\"), SuccessCount = countif(FailureOrSuccess==\"Success\"), IPAddresses = make_set(IPAddress,1000)\n                          by bin(TimeGenerated, authenticationWindow), UserDisplayName, UserPrincipalName\n| extend FailureSuccessDiff = FailureCount - SuccessCount\n| where FailureSuccessDiff > 0\n| summarize Diff = make_list(FailureSuccessDiff, 10000), TimeStamp = make_list(TimeGenerated, 10000) by UserDisplayName, UserPrincipalName//, tostring(IPAddresses)\n| extend (Anomalies, Score, Baseline) = series_decompose_anomalies(Diff, sensitivity, -1, 'linefit')  \n| mv-expand Diff to typeof(double), TimeStamp to typeof(datetime), Anomalies to typeof(double), Score to typeof(double), Baseline to typeof(long)\n| where Anomalies > 0\n| summarize by UserDisplayName, UserPrincipalName, Anomalies, Score, Baseline, FailureToSuccessDiff = Diff\n| join kind=leftouter (\n      SigninLogs\n      | where AppDisplayName =~ \"Windows Sign In\"\n      | extend OS = DeviceDetail.operatingSystem, Browser = DeviceDetail.browser\n      | extend StatusCode = tostring(Status.errorCode), StatusDetails = tostring(Status.additionalDetails)\n      | extend State = tostring(LocationDetails.state), City = tostring(LocationDetails.city)\n      | summarize StartTime = min(TimeGenerated), \n                  EndTime = max(TimeGenerated), \n                  IPAddresses = make_set(IPAddress,100), \n                  OS = make_set(OS,20), \n                  Browser = make_set(Browser,20), \n                  City = make_set(City,100), \n                  ResultType = make_set(ResultType,100)\n              by UserDisplayName, UserPrincipalName, UserId, AppDisplayName\n  ) on UserDisplayName, UserPrincipalName\n| project-away UserDisplayName1, UserPrincipalName1\n| extend IPAddressFirst = tostring(IPAddresses[0])\n| extend Name = tostring(split(UserPrincipalName,'@',0)[0]), UPNSuffix = tostring(split(UserPrincipalName,'@',1)[0])\n",
        "queryFrequency": "P1D",
        "queryPeriod": "P1D",
        "severity": "Medium",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "CredentialAccess"
        ],
        "techniques": [
          "T1110"
        ],
        "templateVersion": "2.0.1",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}