Brute force attack against an Entra-authenticated Windows device

id: 3fbc20a4-04c4-464e-8fcb-6667f53e4987
name: Brute force attack against an Entra-authenticated Windows device
description: |
  'Identifies evidence of brute force activity against Windows devices authenticated via Entra ID (including Entra-joined, hybrid-joined, and Windows 365 Cloud PCs) by detecting multiple authentication failures followed by a successful authentication within a defined time window.'
severity: Medium
requiredDataConnectors:
  - connectorId: AzureActiveDirectory
    dataTypes:
      - SigninLogs
queryFrequency: 1d
queryPeriod: 1d
triggerOperator: gt
triggerThreshold: 0
status: Available
tactics:
  - CredentialAccess
relevantTechniques:
  - T1110
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
  | sort by UserPrincipalName asc, TimeGenerated asc
  | serialize
  | 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])
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: UserPrincipalName
      - identifier: Name
        columnName: Name
      - identifier: UPNSuffix
        columnName: UPNSuffix
  - entityType: Account
    fieldMappings:
      - identifier: AadUserId
        columnName: UserId
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: IPAddressFirst    
version: 2.0.3
kind: Scheduled