Palo Alto Prisma Cloud - High severity alert opened for several days

let ResolvedAlerts = PaloAltoPrismaCloud
| summarize result = make_set(Status) by AlertId
| where result has 'resolved'
| project AlertId;
PaloAltoPrismaCloud
| where Reason =~ 'NEW_ALERT'
| where AlertSeverity =~ 'high' 
| where Status =~ 'open'
| where AlertId !in (ResolvedAlerts)
| extend alert_time = now() - TimeGenerated
| where alert_time > 1d
| extend ['Opened Days'] = strcat('Alert opened for ', strcat(toint(alert_time / 1d), ' days'))
| distinct AlertId, AlertMessage, AlertSeverity, ['Opened Days'], ResourceId, UserName
| extend AccountCustomEntity = UserName

query: |
  let ResolvedAlerts = PaloAltoPrismaCloud
  | summarize result = make_set(Status) by AlertId
  | where result has 'resolved'
  | project AlertId;
  PaloAltoPrismaCloud
  | where Reason =~ 'NEW_ALERT'
  | where AlertSeverity =~ 'high' 
  | where Status =~ 'open'
  | where AlertId !in (ResolvedAlerts)
  | extend alert_time = now() - TimeGenerated
  | where alert_time > 1d
  | extend ['Opened Days'] = strcat('Alert opened for ', strcat(toint(alert_time / 1d), ' days'))
  | distinct AlertId, AlertMessage, AlertSeverity, ['Opened Days'], ResourceId, UserName
  | extend AccountCustomEntity = UserName  
version: 1.0.2
triggerOperator: gt
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/PaloAltoPrismaCloud/Analytic Rules/PaloAltoPrismaCloudHighSeverityAlertOpenedForXDays.yaml
status: Available
description: |
    'Detects high severity alert which is opened for several days.'
queryFrequency: 1d
name: Palo Alto Prisma Cloud - High severity alert opened for several days
kind: Scheduled
triggerThreshold: 0
id: c5bf680f-fa37-47c3-9f38-e839a9b99c05
requiredDataConnectors:
- connectorId: PaloAltoPrismaCloud
  dataTypes:
  - PaloAltoPrismaCloud
severity: Medium
queryPeriod: 14d
entityMappings:
- fieldMappings:
  - columnName: AccountCustomEntity
    identifier: Name
  entityType: Account
relevantTechniques:
- T1133
tactics:
- InitialAccess