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

relevantTechniques:
- T1190
- T1133
- T1071
entityMappings:
- fieldMappings:
  - columnName: SrcIpAddr
    identifier: Address
  entityType: IP
- fieldMappings:
  - columnName: Name
    identifier: Name
  - columnName: UPNSuffix
    identifier: UPNSuffix
  entityType: Account
- fieldMappings:
  - columnName: SrcHostname
    identifier: HostName
  entityType: Host
version: 1.0.0
triggerThreshold: 0
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Web Session Essentials/Analytic Rules/MultipleClientErrorsWithinShortTime.yaml
description: |
    'This detection mechanism identifies situations where multiple client errors originate from a single source within a limited time frame.'
customDetails:
  EventStartTime: EventStartTime
  EventEndTime: EventEndTime
  RequestURLs: URLs
  EventResultSet: EventResultDetailsSet
  TotalErrorCount: TotalErrorCount
  ErrorThreshold: Threshold
requiredDataConnectors: []
triggerOperator: gt
alertDetailsOverride:
  alertDisplayNameFormat: High number of client errors originated by user '{{SrcUsername}}' from IP address '{{SrcIpAddr}}'
  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."
eventGroupingSettings:
  aggregationKind: AlertPerResult
id: faa40333-1e8b-40cc-a003-51ae41fa886f
queryFrequency: 1h
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  
severity: Medium
kind: Scheduled
status: Available
queryPeriod: 1h
name: Detect instances of multiple client errors occurring within a brief period of time (ASIM Web Session)
tactics:
- InitialAccess
- CommandAndControl
tags:
- Schema: WebSession
  SchemaVersion: 0.2.6