Merge pull request #9176 from praveenthepro/patch-3

Update SigninBruteForce-AzurePortal.yaml
Azure · Oct 10, 2023 · a4dad22 · a4dad22
2 parents d527754 + 1f3a25b
commit a4dad22
Showing 1 changed file with 62 additions and 45 deletions.
diff --git a/Solutions/Azure Active Directory/Analytic Rules/SigninBruteForce-AzurePortal.yaml b/Solutions/Azure Active Directory/Analytic Rules/SigninBruteForce-AzurePortal.yaml
@@ -1,9 +1,8 @@
 id: 28b42356-45af-40a6-a0b4-a554cdfd5d8a
 name: Brute force attack against Azure Portal
-description: |
-  'Identifies evidence of brute force activity against Azure Portal by highlighting multiple authentication failures and by a successful authentication within a given time window. 
-  Default Failure count is 10 and default Time Window is 20 minutes.
-  References: https://docs.microsoft.com/azure/active-directory/reports-monitoring/reference-sign-ins-error-codes.'
+description: >
+  Detects Azure Portal brute force attacks by monitoring for multiple authentication failures and a successful login within a 20-minute window. Default settings: 10 failures, 25 deviations.
+  Ref: https://docs.microsoft.com/azure/active-directory/reports-monitoring/reference-sign-ins-error-codes.
 severity: Medium
 requiredDataConnectors:
   - connectorId: AzureActiveDirectory
@@ -13,7 +12,7 @@ requiredDataConnectors:
     dataTypes:
       - AADNonInteractiveUserSignInLogs
 queryFrequency: 1d
-queryPeriod: 1d
+queryPeriod: 7d
 triggerOperator: gt
 triggerThreshold: 0
 status: Available
@@ -22,48 +21,64 @@ tactics:
 relevantTechniques:
   - T1110
 query: |
- let timeRange = 24h;
- let failureCountThreshold = 10;
- let authenticationWindow = 20m;
- let aadFunc = (tableName:string){
-  table(tableName)
- | where AppDisplayName has "Azure Portal"
- | extend
-      DeviceDetail = todynamic(DeviceDetail),
-      //Status = todynamic(Status),
-      LocationDetails = todynamic(LocationDetails)
- | extend
-      OS = tostring(DeviceDetail.operatingSystem),
-      Browser = tostring(DeviceDetail.browser),
-      //StatusCode = tostring(Status.errorCode),
-      //StatusDetails = tostring(Status.additionalDetails),
-      State = tostring(LocationDetails.state),
-      City = tostring(LocationDetails.city),
-      Region = tostring(LocationDetails.countryOrRegion)
- // Split out failure versus non-failure types
- | extend FailureOrSuccess = iff(ResultType in ("0", "50125", "50140", "70043", "70044"), "Success", "Failure")  
- // sort for sessionizing - by UserPrincipalName and time of the authentication outcome
- | sort by UserPrincipalName asc, TimeGenerated asc
- // sessionize into failure groupings until either the account changes or there is a success
- | extend SessionStartedUtc = row_window_session(TimeGenerated, timeRange, authenticationWindow, UserPrincipalName != prev(UserPrincipalName) or prev(FailureOrSuccess) == "Success")
- // bin outcomes based on authenticationWindow
- | summarize FailureOrSuccessCount = count() by  FailureOrSuccess, UserId, UserDisplayName, AppDisplayName, IPAddress, Browser, OS, State, City, Region, Type, CorrelationId, bin(TimeGenerated, authenticationWindow), ResultType, UserPrincipalName,SessionStartedUtc
- // count the failures in each session
- | summarize FailureCountBeforeSuccess=sumif(FailureOrSuccessCount, FailureOrSuccess == "Failure"), StartTime=min(TimeGenerated), EndTime=max(TimeGenerated), makelist(FailureOrSuccess), IPAddress = make_set(IPAddress,15), make_set(Browser,15), make_set(City,15), make_set(State,15), make_set(Region,15), make_set(ResultType,15) by SessionStartedUtc, UserPrincipalName, CorrelationId, AppDisplayName, UserId, Type
- // the session must not start with a success, and must end with one
- | where array_index_of(list_FailureOrSuccess, "Success") != 0
- | where array_index_of(list_FailureOrSuccess, "Success") == array_length(list_FailureOrSuccess) - 1
- | project-away SessionStartedUtc, list_FailureOrSuccess
- // where the number of failures before the success is above the threshold 
- | where FailureCountBeforeSuccess >= failureCountThreshold 
- // expand out ip for entity assignment
- | mv-expand IPAddress
- | extend IPAddress = tostring(IPAddress)
- | extend timestamp = StartTime 
- };
+  // Set threshold value for deviation
+  let threshold = 25;
+  // Set the time range for the query
+  let timeRange = 24h;
+  // Set the authentication window duration
+  let authenticationWindow = 20m;
+  // Define a reusable function 'aadFunc' that takes a table name as input
+  let aadFunc = (tableName: string) {
+    // Query the specified table
+    table(tableName)
+    // Filter data within the last 24 hours
+    | where TimeGenerated > ago(1d)
+    // Filter records related to "Azure Portal" applications
+    | where AppDisplayName has "Azure Portal"
+    // Extract and transform some fields
+    | extend
+        DeviceDetail = todynamic(DeviceDetail),
+        LocationDetails = todynamic(LocationDetails)
+    | extend
+        OS = tostring(DeviceDetail.operatingSystem),
+        Browser = tostring(DeviceDetail.browser),
+        State = tostring(LocationDetails.state),
+        City = tostring(LocationDetails.city),
+        Region = tostring(LocationDetails.countryOrRegion)
+    // Categorize records as Success or Failure based on ResultType
+    | extend FailureOrSuccess = iff(ResultType in ("0", "50125", "50140", "70043", "70044"), "Success", "Failure")
+    // Sort and identify sessions
+    | sort by UserPrincipalName asc, TimeGenerated asc
+    | extend SessionStartedUtc = row_window_session(TimeGenerated, timeRange, authenticationWindow, UserPrincipalName != prev(UserPrincipalName) or prev(FailureOrSuccess) == "Success")
+    // Summarize data
+    | summarize FailureOrSuccessCount = count() by  FailureOrSuccess, UserId, UserDisplayName, AppDisplayName, IPAddress, Browser, OS, State, City, Region, Type, CorrelationId, bin(TimeGenerated, authenticationWindow), ResultType, UserPrincipalName, SessionStartedUtc
+    | summarize FailureCountBeforeSuccess = sumif(FailureOrSuccessCount, FailureOrSuccess == "Failure"), StartTime = min(TimeGenerated), EndTime = max(TimeGenerated), makelist(FailureOrSuccess), IPAddress = make_set(IPAddress, 15), make_set(Browser, 15), make_set(City, 15), make_set(State, 15), make_set(Region, 15), make_set(ResultType, 15) by SessionStartedUtc, UserPrincipalName, CorrelationId, AppDisplayName, UserId, Type
+    // Filter records where "Success" occurs in the middle of a session
+    | where array_index_of(list_FailureOrSuccess, "Success") != 0
+    | where array_index_of(list_FailureOrSuccess, "Success") == array_length(list_FailureOrSuccess) - 1
+    // Remove unnecessary columns from the output
+    | project-away SessionStartedUtc, list_FailureOrSuccess
+    // Join with another table and calculate deviation
+    | join kind=inner (
+        table(tableName)
+        | where TimeGenerated > ago(7d)
+        | where AppDisplayName has "Azure Portal"
+        | extend FailureOrSuccess = iff(ResultType in ("0", "50125", "50140", "70043", "70044"), "Success", "Failure")
+        | summarize avgFailures = avg(todouble(FailureOrSuccess == "Failure")) by UserPrincipalName
+    ) on UserPrincipalName
+    | extend Deviation = abs(FailureCountBeforeSuccess - avgFailures) / avgFailures
+    // Filter records based on deviation and failure count criteria
+    | where Deviation > threshold and FailureCountBeforeSuccess >= 10
+    // Expand the IPAddress array
+    | mv-expand IPAddress
+    | extend IPAddress = tostring(IPAddress)
+    | extend timestamp = StartTime
+  };
+  // Call 'aadFunc' with different table names and union the results
   let aadSignin = aadFunc("SigninLogs");
   let aadNonInt = aadFunc("AADNonInteractiveUserSignInLogs");
   union isfuzzy=true aadSignin, aadNonInt
+  // Additional transformation: Split UserPrincipalName
   | extend Name = tostring(split(UserPrincipalName,'@',0)[0]), UPNSuffix = tostring(split(UserPrincipalName,'@',1)[0])
 entityMappings:
   - entityType: Account
@@ -72,9 +87,11 @@ entityMappings:
       columnName: Name
     - identifier: UPNSuffix
       columnName: UPNSuffix
+    - identifier: AadUserId
+      columnName: UserId
   - entityType: IP
     fieldMappings:
       - identifier: Address
         columnName: IPAddress
-version: 2.1.1
+version: 2.1.2
 kind: Scheduled