Detect Print Processors Registry Driver Key CreationModification

// Print Processor Registry Key RegEx
let printProcessorRegistryRegEx = @'HKEY_LOCAL_MACHINE\\SYSTEM\\[A-Za-z0-9]*ControlSet[A-Za-z0-9]*\\Control\\Print\\Environments\\Windows\s[A-Za-z0-9]+\\Print Processors\\[A-Za-z0-9]+\\Driver';
_ASim_RegistryEvent
| where EventType in ('RegistryValueSet', 'RegistryKeyCreated')
| where RegistryKey matches regex printProcessorRegistryRegEx
| project
    TimeGenerated,
    DvcHostname,
    ActorUsername,
    ActorUsernameType,
    ActingProcessId,
    ActingProcessName,
    ActingProcessCommandLine,
    RegistryKey,
    RegistryValue,
    RegistryValueType,
    RegistryValueData
| extend HostName = tostring(split(DvcHostname, '.')[0])
| extend DnsDomain = tostring(strcat_array(array_slice(split(DvcHostname, '.'), 1, -1), '.'))
| extend Username = iff(tostring(ActorUsernameType) == 'Windows', tostring(split(ActorUsername, '\\')[1]), ActorUsername)
| extend NTDomain = iff(tostring(ActorUsernameType) == 'Windows', tostring(split(ActorUsername, '\\')[0]), ActorUsername)
| extend Username = iff(tostring(ActorUsernameType) == 'UPN', tostring(split(ActorUsername, '@')[0]), Username)
| extend UPNSuffix = iff(tostring(ActorUsernameType) == 'UPN', tostring(split(ActorUsername, '@')[1]), '')
| extend RegHive = tostring(split(RegistryKey, '\\')[0]), RegKey = tostring(strcat_array(array_slice(split(RegistryKey, '\\'), 1, -1), '\\')) 

relevantTechniques:
- T1547
tags:
- Schema: _ASim_RegistryEvent
  SchemaVersion: 0.1.2
name: Detect Print Processors Registry Driver Key Creation/Modification
triggerThreshold: 0
tactics:
- Persistence
- PrivilegeEscalation
alertDetailsOverride:
  alertDisplayNameFormat: Print Processor Registry Driver Keys Modified on {{DvcHostname}} ({{DvcIpAddr}}) by ({{ActorUsername}})
  alertDescriptionFormat: 'Process {{ActingProcessName}} ProcessId: ({{ActingProcessId}}) modified registry driver key {{RegistryKey}}.'
severity: Medium
id: 7edde3d4-9859-4a00-b93c-b19ddda55320
status: Available
requiredDataConnectors:
- dataTypes:
  - CommonSecurityLog
  connectorId: CrowdStrikeFalconEndpointProtection
- dataTypes:
  - SecurityAlert
  connectorId: MicrosoftThreatProtection
- dataTypes:
  - SentinelOne_CL
  connectorId: SentinelOne
- dataTypes:
  - CarbonBlackEvents_CL
  connectorId: VMwareCarbonBlack
- dataTypes:
  - CiscoSecureEndpoint_CL
  connectorId: CiscoSecureEndpoint
- dataTypes:
  - TMApexOneEvent
  connectorId: TrendMicroApexOne
- dataTypes:
  - TMApexOneEvent
  connectorId: TrendMicroApexOneAma
kind: Scheduled
query: |
  // Print Processor Registry Key RegEx
  let printProcessorRegistryRegEx = @'HKEY_LOCAL_MACHINE\\SYSTEM\\[A-Za-z0-9]*ControlSet[A-Za-z0-9]*\\Control\\Print\\Environments\\Windows\s[A-Za-z0-9]+\\Print Processors\\[A-Za-z0-9]+\\Driver';
  _ASim_RegistryEvent
  | where EventType in ('RegistryValueSet', 'RegistryKeyCreated')
  | where RegistryKey matches regex printProcessorRegistryRegEx
  | project
      TimeGenerated,
      DvcHostname,
      ActorUsername,
      ActorUsernameType,
      ActingProcessId,
      ActingProcessName,
      ActingProcessCommandLine,
      RegistryKey,
      RegistryValue,
      RegistryValueType,
      RegistryValueData
  | extend HostName = tostring(split(DvcHostname, '.')[0])
  | extend DnsDomain = tostring(strcat_array(array_slice(split(DvcHostname, '.'), 1, -1), '.'))
  | extend Username = iff(tostring(ActorUsernameType) == 'Windows', tostring(split(ActorUsername, '\\')[1]), ActorUsername)
  | extend NTDomain = iff(tostring(ActorUsernameType) == 'Windows', tostring(split(ActorUsername, '\\')[0]), ActorUsername)
  | extend Username = iff(tostring(ActorUsernameType) == 'UPN', tostring(split(ActorUsername, '@')[0]), Username)
  | extend UPNSuffix = iff(tostring(ActorUsernameType) == 'UPN', tostring(split(ActorUsername, '@')[1]), '')
  | extend RegHive = tostring(split(RegistryKey, '\\')[0]), RegKey = tostring(strcat_array(array_slice(split(RegistryKey, '\\'), 1, -1), '\\'))   
description: |
    This analytic rule detects any registry value creation or modification of print processor registry Driver key. This will load the executable at startup with print spooler service. This could be an indication of a persistence attempt by an adversary.
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Malware Protection Essentials/Analytic Rules/PrintProcessersModified.yaml
triggerOperator: gt
queryPeriod: 1h
queryFrequency: 1h
eventGroupingSettings:
  aggregationKind: SingleAlert
version: 1.0.0
entityMappings:
- entityType: Host
  fieldMappings:
  - columnName: HostName
    identifier: HostName
  - columnName: DnsDomain
    identifier: DnsDomain
  - columnName: NTDomain
    identifier: NTDomain
- entityType: Account
  fieldMappings:
  - columnName: Username
    identifier: Name
  - columnName: UPNSuffix
    identifier: UPNSuffix
  - columnName: NTDomain
    identifier: NTDomain
- entityType: Process
  fieldMappings:
  - columnName: ActingProcessId
    identifier: ProcessId
  - columnName: ActingProcessCommandLine
    identifier: CommandLine
- entityType: RegistryKey
  fieldMappings:
  - columnName: RegHive
    identifier: Hive
  - columnName: RegKey
    identifier: Key
- entityType: RegistryValue
  fieldMappings:
  - columnName: RegistryValue
    identifier: Name
  - columnName: RegistryValueData
    identifier: Value
  - columnName: RegistryValueType
    identifier: ValueType