Vectra AI Detect - Suspected Compromised Account

// Edit this variable to only keep the Severity level where an incident needs to be created.
//Level of severity are: Low, Medium, High, Critical). Recommended configuration is to trigger an alert for at least High and Critical.'
let configured_level = dynamic(["High", "Critical"]);
let upn_has_prefix = ":";
CommonSecurityLog
| where DeviceVendor == "Vectra Networks"
| where DeviceProduct == "X Series"
| where DeviceEventClassID == "asc"
| extend saccount = extract("saccount=(.+?);", 1, AdditionalExtensions)
| extend type = iff(saccount matches regex upn_has_prefix, tostring(split(saccount,":")[0]) ,"network" ) 
| extend upn = iff(saccount matches regex upn_has_prefix, tostring(split(saccount,":")[1]) , saccount )
| extend name = tostring(split(upn,"@")[0])
| extend upn_suffix = tostring(split(upn,"@")[1])
| project-rename threat_score = FlexNumber1
| project-rename certainty_score = FlexNumber2
| project-rename vectra_URL = DeviceCustomString4
| project-rename detection_name = DeviceEventClassID
| project-rename score_decreases = DeviceCustomString3
| extend level = case( threat_score <  50 and certainty_score < 50, "Low",
                      threat_score < 50 and certainty_score >= 50 , "Medium", 
                      threat_score >= 50 and certainty_score <= 50, "High", 
                      threat_score >= 50 and certainty_score >= 50, "Critical",
                      "UNKNOWN")
| extend Severity = case(level == "Info", "Informational",level == "Critical", "High", level)
| where level in (configured_level) 
//keep only the event with the highest threat score per Host
| summarize arg_max(threat_score, *) by saccount
| sort by TimeGenerated

entityMappings:
- entityType: Account
  fieldMappings:
  - identifier: Name
    columnName: name
  - identifier: UPNSuffix
    columnName: upn_suffix
tactics:
- CredentialAccess
- Discovery
- LateralMovement
- Collection
- CommandAndControl
- Exfiltration
- Impact
requiredDataConnectors:
- dataTypes:
  - CommonSecurityLog
  connectorId: CefAma
alertDetailsOverride:
  alertDisplayNameFormat: Vectra AI Detect - Account {{saccount}} reaches {{level}} severity
  alertDescriptionFormat: |
    The account {{saccount}} has a threat score of {{threat_score}} and a
    certainty of {{certainty_score}}    
  alertSeverityColumnName: Severity
  alertDynamicProperties:
  - value: vectra_URL
    alertProperty: AlertLink
  - value: DeviceProduct
    alertProperty: ProductName
  - value: DeviceVendor
    alertProperty: ProviderName
  - value: certainty_score
    alertProperty: ConfidenceScore
incidentConfiguration:
  groupingConfiguration:
    enabled: true
    lookbackDuration: 7d
    reopenClosedIncident: true
    matchingMethod: AllEntities
  createIncident: true
id: 321f9dbd-64b7-4541-81dc-08cf7732ccb0
severity: Informational
status: Available
customDetails:
  ScoreDecrease: score_decreases
query: |
  // Edit this variable to only keep the Severity level where an incident needs to be created.
  //Level of severity are: Low, Medium, High, Critical). Recommended configuration is to trigger an alert for at least High and Critical.'
  let configured_level = dynamic(["High", "Critical"]);
  let upn_has_prefix = ":";
  CommonSecurityLog
  | where DeviceVendor == "Vectra Networks"
  | where DeviceProduct == "X Series"
  | where DeviceEventClassID == "asc"
  | extend saccount = extract("saccount=(.+?);", 1, AdditionalExtensions)
  | extend type = iff(saccount matches regex upn_has_prefix, tostring(split(saccount,":")[0]) ,"network" ) 
  | extend upn = iff(saccount matches regex upn_has_prefix, tostring(split(saccount,":")[1]) , saccount )
  | extend name = tostring(split(upn,"@")[0])
  | extend upn_suffix = tostring(split(upn,"@")[1])
  | project-rename threat_score = FlexNumber1
  | project-rename certainty_score = FlexNumber2
  | project-rename vectra_URL = DeviceCustomString4
  | project-rename detection_name = DeviceEventClassID
  | project-rename score_decreases = DeviceCustomString3
  | extend level = case( threat_score <  50 and certainty_score < 50, "Low",
                        threat_score < 50 and certainty_score >= 50 , "Medium", 
                        threat_score >= 50 and certainty_score <= 50, "High", 
                        threat_score >= 50 and certainty_score >= 50, "Critical",
                        "UNKNOWN")
  | extend Severity = case(level == "Info", "Informational",level == "Critical", "High", level)
  | where level in (configured_level) 
  //keep only the event with the highest threat score per Host
  | summarize arg_max(threat_score, *) by saccount
  | sort by TimeGenerated  
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Vectra AI Detect/Analytic Rules/VectraDetect-Account-by-Severity.yaml
kind: Scheduled
queryPeriod: 5m
version: 1.0.9
name: Vectra AI Detect - Suspected Compromised Account
queryFrequency: 5m
eventGroupingSettings:
  aggregationKind: AlertPerResult
relevantTechniques:
- T1003
- T1087
- T1021
- T1119
- T1071
- T1041
- T1499
description: |
  'Create an incident when an Account is suspected to be compromised. 
  The higher the severity level is, the more immediate attention it requires as Vectra AI engine is more confident that this is a real threat. 
  Level of severity are: Low, Medium, High, Critical). Recommended configuration is to trigger an alert for at least High and Critical.'  
triggerThreshold: 0
triggerOperator: gt