Detect instances of multiple server 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 update threshold value as per your environment
_Im_WebSession(starttime=ago(1h))
| where toint(EventResultDetails) between (500 .. 599)
| summarize
    TotalErrorCount = count(),
    URLs=make_set(Url, 100),
    EventStartTime = min(TimeGenerated),
    EventEndTime = max(TimeGenerated),
    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

customDetails:
  EventStartTime: EventStartTime
  EventResultSet: EventResultDetailsSet
  RequestURLs: URLs
  ErrorThreshold: Threshold
  TotalErrorCount: TotalErrorCount
  EventEndTime: EventEndTime
triggerOperator: gt
queryFrequency: 1h
description: |
    'This detection mechanism identifies situations where multiple server errors originate from a single source within a limited time frame.'
alertDetailsOverride:
  alertDescriptionFormat: "The client has made a total of '{{TotalErrorCount}}' requests to URLs '{{URLs}}', which have resulted in server errors. It is recommended to thoroughly investigate this alert to determine the underlying cause behind this significant number of errors. 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 server errors originated by user '{{SrcUsername}}' from IP address '{{SrcIpAddr}}'
status: Available
kind: Scheduled
triggerThreshold: 0
requiredDataConnectors: []
version: 1.0.0
eventGroupingSettings:
  aggregationKind: AlertPerResult
queryPeriod: 1h
name: Detect instances of multiple server errors occurring within a brief period of time (ASIM Web Session)
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Web Session Essentials/Analytic Rules/MultipleServerErrorsWithinShortTime.yaml
id: a59ba76c-0205-4966-948e-3d5640140688
tags:
- Schema: WebSession
  SchemaVersion: 0.2.6
tactics:
- InitialAccess
- Impact
relevantTechniques:
- T1190
- T1133
- T1498
severity: Medium
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
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 update threshold value as per your environment
  _Im_WebSession(starttime=ago(1h))
  | where toint(EventResultDetails) between (500 .. 599)
  | summarize
      TotalErrorCount = count(),
      URLs=make_set(Url, 100),
      EventStartTime = min(TimeGenerated),
      EventEndTime = max(TimeGenerated),
      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  

{
  "$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/a59ba76c-0205-4966-948e-3d5640140688')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/a59ba76c-0205-4966-948e-3d5640140688')]",
      "properties": {
        "alertDetailsOverride": {
          "alertDescriptionFormat": "The client has made a total of '{{TotalErrorCount}}' requests to URLs '{{URLs}}', which have resulted in server errors. It is recommended to thoroughly investigate this alert to determine the underlying cause behind this significant number of errors. 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 server errors originated by user '{{SrcUsername}}' from IP address '{{SrcIpAddr}}'"
        },
        "alertRuleTemplateName": "a59ba76c-0205-4966-948e-3d5640140688",
        "customDetails": {
          "ErrorThreshold": "Threshold",
          "EventEndTime": "EventEndTime",
          "EventResultSet": "EventResultDetailsSet",
          "EventStartTime": "EventStartTime",
          "RequestURLs": "URLs",
          "TotalErrorCount": "TotalErrorCount"
        },
        "description": "'This detection mechanism identifies situations where multiple server errors originate from a single source within a limited time frame.'\n",
        "displayName": "Detect instances of multiple server 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 Session Essentials/Analytic Rules/MultipleServerErrorsWithinShortTime.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 update threshold value as per your environment\n_Im_WebSession(starttime=ago(1h))\n| where toint(EventResultDetails) between (500 .. 599)\n| summarize\n    TotalErrorCount = count(),\n    URLs=make_set(Url, 100),\n    EventStartTime = min(TimeGenerated),\n    EventEndTime = max(TimeGenerated),\n    EventResultDetailsSet=make_set(EventResultDetails,10)\n    by SrcIpAddr, bin(TimeGenerated, 5m), SrcUsername, SrcHostname\n| where TotalErrorCount > threshold\n| extend\n    Name = iif(SrcUsername contains \"@\", tostring(split(SrcUsername, '@', 0)[0]), SrcUsername),\n    UPNSuffix = iif(SrcUsername contains \"@\", tostring(split(SrcUsername, '@', 1)[0]), \"\"), Threshold=threshold\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "Medium",
        "status": "Available",
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Impact",
          "InitialAccess"
        ],
        "tags": [
          {
            "Schema": "WebSession",
            "SchemaVersion": "0.2.6"
          }
        ],
        "techniques": [
          "T1133",
          "T1190",
          "T1498"
        ],
        "templateVersion": "1.0.0",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}