Detect instances of multiple client errors occurring within a brief period of time ASIM Web Session

// HTTP response status codes indicate whether a specific HTTP request has been successfully completed.
// Please refer this for more details: https://developer.mozilla.org/en-US/docs/Web/HTTP/Status
let threshold = 100; // You can set threshold value that suits your environment
_Im_WebSession(starttime=ago(1h))
| where toint(EventResultDetails) between (400 .. 499)
| summarize
    TotalErrorCount = count(),
    EventStartTime = min(TimeGenerated),
    EventEndTime = max(TimeGenerated),
    URLs=make_set(Url, 100),
    EventResultDetailsSet=make_set(EventResultDetails,10)
    by SrcIpAddr, bin(TimeGenerated, 5m), SrcUsername, SrcHostname
| where TotalErrorCount > threshold
| extend Name = iif(SrcUsername contains "@", tostring(split(SrcUsername,'@',0)[0]),SrcUsername), UPNSuffix = iif(SrcUsername contains "@",tostring(split(SrcUsername,'@',1)[0]),""), Threshold=threshold

name: Detect instances of multiple client errors occurring within a brief period of time (ASIM Web Session)
triggerOperator: gt
query: |
  // HTTP response status codes indicate whether a specific HTTP request has been successfully completed.
  // Please refer this for more details: https://developer.mozilla.org/en-US/docs/Web/HTTP/Status
  let threshold = 100; // You can set threshold value that suits your environment
  _Im_WebSession(starttime=ago(1h))
  | where toint(EventResultDetails) between (400 .. 499)
  | summarize
      TotalErrorCount = count(),
      EventStartTime = min(TimeGenerated),
      EventEndTime = max(TimeGenerated),
      URLs=make_set(Url, 100),
      EventResultDetailsSet=make_set(EventResultDetails,10)
      by SrcIpAddr, bin(TimeGenerated, 5m), SrcUsername, SrcHostname
  | where TotalErrorCount > threshold
  | extend Name = iif(SrcUsername contains "@", tostring(split(SrcUsername,'@',0)[0]),SrcUsername), UPNSuffix = iif(SrcUsername contains "@",tostring(split(SrcUsername,'@',1)[0]),""), Threshold=threshold
queryFrequency: 1h
description: |
  'This detection mechanism identifies situations where multiple client errors originate from a single source within a limited time frame.'
id: faa40333-1e8b-40cc-a003-51ae41fa886f
triggerThreshold: 0
queryPeriod: 1h
version: 1.0.0
kind: Scheduled
customDetails:
  EventEndTime: EventEndTime
  EventResultSet: EventResultDetailsSet
  TotalErrorCount: TotalErrorCount
  EventStartTime: EventStartTime
  ErrorThreshold: Threshold
  RequestURLs: URLs
status: Available
tags:
- SchemaVersion: 0.2.6
  Schema: WebSession
eventGroupingSettings:
  aggregationKind: AlertPerResult
severity: Medium
requiredDataConnectors: []
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Web%20Session%20Essentials/Analytic%20Rules/MultipleClientErrorsWithinShortTime.yaml
alertDetailsOverride:
  alertDescriptionFormat: "The client has made a total of '{{TotalErrorCount}}' requests to URLs '{{URLs}}', which have resulted in client errors. A sudden surge in HTTP code errors, especially in the form of client-side errors like 400 or 401, could indicate malicious activity, such as attackers attempting to exploit vulnerabilities or perform unauthorized actions. For detailed information regarding the specific errors encountered, please refer to the following link: https://developer.mozilla.org/en-US/docs/Web/HTTP/Status."
  alertDisplayNameFormat: High number of client errors originated by user '{{SrcUsername}}' from IP address '{{SrcIpAddr}}'
relevantTechniques:
- T1190
- T1133
- T1071
tactics:
- InitialAccess
- CommandAndControl
entityMappings:
- fieldMappings:
  - identifier: Address
    columnName: SrcIpAddr
  entityType: IP
- fieldMappings:
  - identifier: Name
    columnName: Name
  - identifier: UPNSuffix
    columnName: UPNSuffix
  entityType: Account
- fieldMappings:
  - identifier: HostName
    columnName: SrcHostname
  entityType: Host

{
  "$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/faa40333-1e8b-40cc-a003-51ae41fa886f')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/faa40333-1e8b-40cc-a003-51ae41fa886f')]",
      "properties": {
        "alertDetailsOverride": {
          "alertDescriptionFormat": "The client has made a total of '{{TotalErrorCount}}' requests to URLs '{{URLs}}', which have resulted in client errors. A sudden surge in HTTP code errors, especially in the form of client-side errors like 400 or 401, could indicate malicious activity, such as attackers attempting to exploit vulnerabilities or perform unauthorized actions. For detailed information regarding the specific errors encountered, please refer to the following link: https://developer.mozilla.org/en-US/docs/Web/HTTP/Status.",
          "alertDisplayNameFormat": "High number of client errors originated by user '{{SrcUsername}}' from IP address '{{SrcIpAddr}}'"
        },
        "alertRuleTemplateName": "faa40333-1e8b-40cc-a003-51ae41fa886f",
        "customDetails": {
          "ErrorThreshold": "Threshold",
          "EventEndTime": "EventEndTime",
          "EventResultSet": "EventResultDetailsSet",
          "EventStartTime": "EventStartTime",
          "RequestURLs": "URLs",
          "TotalErrorCount": "TotalErrorCount"
        },
        "description": "'This detection mechanism identifies situations where multiple client errors originate from a single source within a limited time frame.'\n",
        "displayName": "Detect instances of multiple client errors occurring within a brief period of time (ASIM Web Session)",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "SrcIpAddr",
                "identifier": "Address"
              }
            ]
          },
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "Name",
                "identifier": "Name"
              },
              {
                "columnName": "UPNSuffix",
                "identifier": "UPNSuffix"
              }
            ]
          },
          {
            "entityType": "Host",
            "fieldMappings": [
              {
                "columnName": "SrcHostname",
                "identifier": "HostName"
              }
            ]
          }
        ],
        "eventGroupingSettings": {
          "aggregationKind": "AlertPerResult"
        },
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Web%20Session%20Essentials/Analytic%20Rules/MultipleClientErrorsWithinShortTime.yaml",
        "query": "// HTTP response status codes indicate whether a specific HTTP request has been successfully completed.\n// Please refer this for more details: https://developer.mozilla.org/en-US/docs/Web/HTTP/Status\nlet threshold = 100; // You can set threshold value that suits your environment\n_Im_WebSession(starttime=ago(1h))\n| where toint(EventResultDetails) between (400 .. 499)\n| summarize\n    TotalErrorCount = count(),\n    EventStartTime = min(TimeGenerated),\n    EventEndTime = max(TimeGenerated),\n    URLs=make_set(Url, 100),\n    EventResultDetailsSet=make_set(EventResultDetails,10)\n    by SrcIpAddr, bin(TimeGenerated, 5m), SrcUsername, SrcHostname\n| where TotalErrorCount > threshold\n| extend Name = iif(SrcUsername contains \"@\", tostring(split(SrcUsername,'@',0)[0]),SrcUsername), UPNSuffix = iif(SrcUsername contains \"@\",tostring(split(SrcUsername,'@',1)[0]),\"\"), Threshold=threshold\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "Medium",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "CommandAndControl",
          "InitialAccess"
        ],
        "tags": [
          {
            "Schema": "WebSession",
            "SchemaVersion": "0.2.6"
          }
        ],
        "techniques": [
          "T1071",
          "T1133",
          "T1190"
        ],
        "templateVersion": "1.0.0",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}