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), '\\')) 

entityMappings:
- fieldMappings:
  - columnName: HostName
    identifier: HostName
  - columnName: DnsDomain
    identifier: DnsDomain
  - columnName: NTDomain
    identifier: NTDomain
  entityType: Host
- fieldMappings:
  - columnName: Username
    identifier: Name
  - columnName: UPNSuffix
    identifier: UPNSuffix
  - columnName: NTDomain
    identifier: NTDomain
  entityType: Account
- fieldMappings:
  - columnName: ActingProcessId
    identifier: ProcessId
  - columnName: ActingProcessCommandLine
    identifier: CommandLine
  entityType: Process
- fieldMappings:
  - columnName: RegHive
    identifier: Hive
  - columnName: RegKey
    identifier: Key
  entityType: RegistryKey
- fieldMappings:
  - columnName: RegistryValue
    identifier: Name
  - columnName: RegistryValueData
    identifier: Value
  - columnName: RegistryValueType
    identifier: ValueType
  entityType: RegistryValue
alertDetailsOverride:
  alertDisplayNameFormat: Print Processor Registry Driver Keys Modified on {{DvcHostname}} ({{DvcIpAddr}}) by ({{ActorUsername}})
  alertDescriptionFormat: 'Process {{ActingProcessName}} ProcessId: ({{ActingProcessId}}) modified registry driver key {{RegistryKey}}.'
status: Available
queryFrequency: 1h
tactics:
- Persistence
- PrivilegeEscalation
triggerThreshold: 0
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), '\\'))   
queryPeriod: 1h
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Malware Protection Essentials/Analytic Rules/PrintProcessersModified.yaml
relevantTechniques:
- T1547
version: 1.0.0
kind: Scheduled
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
triggerOperator: gt
severity: Medium
id: 7edde3d4-9859-4a00-b93c-b19ddda55320
eventGroupingSettings:
  aggregationKind: SingleAlert
tags:
- Schema: _ASim_RegistryEvent
  SchemaVersion: 0.1.2
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.
name: Detect Print Processors Registry Driver Key Creation/Modification