Detect Print Processors Registry Driver Key Creation/Modification

Status: available
Severity: medium
Time window: 1h
Source: github.com/Azure/Azure-Sentinel

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.

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1547` Boot or Logon Autostart Execution
Privilege Escalation	`T1547` Boot or Logon Autostart Execution

Event coverage

Provider	Event/ActionType	Title
Sysmon	Event ID 12	RegistryEvent (Object create and delete)
Sysmon	Event ID 13	RegistryEvent (Value Set)
Sysmon	Event ID 14	RegistryEvent (Key and Value Rename)
Security-Auditing	Event ID 4657	A registry value was modified.
Security-Auditing	Event ID 4660	An object was deleted.
Security-Auditing	Event ID 4663	An attempt was made to access an object.
Defender-DeviceRegistryEvents	RegistryKeyDeleted	Registry key deleted
Defender-DeviceRegistryEvents	RegistryValueSet	Registry value set
Defender-DeviceRegistryEvents	RegistryValueDeleted	Registry value deleted
Defender-DeviceRegistryEvents	RegistryKeyRenamed	Registry key renamed

Rule body kusto

id: 7edde3d4-9859-4a00-b93c-b19ddda55320
name: Detect Print Processors Registry Driver Key Creation/Modification
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.
severity: Medium
status: Available 
tags:
  - Schema: _ASim_RegistryEvent
    SchemaVersion: 0.1.2
requiredDataConnectors:
  - connectorId: CrowdStrikeFalconEndpointProtection
    dataTypes: 
      - CommonSecurityLog
  - connectorId: MicrosoftThreatProtection
    dataTypes:
      - SecurityAlert
  - connectorId: SentinelOne
    dataTypes:
      - SentinelOne_CL
  - connectorId: VMwareCarbonBlack
    dataTypes:
      - CarbonBlackEvents_CL
  - connectorId: CiscoSecureEndpoint
    dataTypes:
      - CiscoSecureEndpoint_CL
  - connectorId: TrendMicroApexOne
    dataTypes:
      - TMApexOneEvent
  - connectorId: TrendMicroApexOneAma
    dataTypes:
      - TMApexOneEvent
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Persistence
  - PrivilegeEscalation
relevantTechniques:
  - T1547
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), '\\')) 
entityMappings:
  - entityType: Host
    fieldMappings:
      - identifier: HostName
        columnName: HostName
      - identifier: DnsDomain
        columnName: DnsDomain
      - identifier: NTDomain
        columnName: NTDomain
  - entityType: Account
    fieldMappings:
      - identifier: Name
        columnName: Username
      - identifier: UPNSuffix
        columnName: UPNSuffix
      - identifier: NTDomain
        columnName: NTDomain
  - entityType: Process
    fieldMappings:
      - identifier: ProcessId
        columnName: ActingProcessId
      - identifier: CommandLine
        columnName: ActingProcessCommandLine
  - entityType: RegistryKey
    fieldMappings:
      - identifier: Hive
        columnName: RegHive
      - identifier: Key
        columnName: RegKey
  - entityType: RegistryValue
    fieldMappings:
      - identifier: Name
        columnName: RegistryValue
      - identifier: Value
        columnName: RegistryValueData
      - identifier: ValueType
        columnName: RegistryValueType
eventGroupingSettings:
  aggregationKind: SingleAlert
alertDetailsOverride:
  alertDisplayNameFormat: "Print Processor Registry Driver Keys Modified on {{DvcHostname}} ({{DvcIpAddr}}) by ({{ActorUsername}})"
  alertDescriptionFormat: "Process {{ActingProcessName}} ProcessId: ({{ActingProcessId}}) modified registry driver key {{RegistryKey}}."
version: 1.0.0
kind: Scheduled

Stages and Predicates

Let binding: `printProcessorRegistryRegEx`

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';

Stage 1: `source`

_ASim_RegistryEvent

Stage 2: `where`

| where EventType in ('RegistryValueSet', 'RegistryKeyCreated')

Stage 3: `where`

| where RegistryKey matches regex printProcessorRegistryRegEx

References printProcessorRegistryRegEx (defined above).

Stage 4: `project`

| project
    TimeGenerated,
    DvcHostname,
    ActorUsername,
    ActorUsernameType,
    ActingProcessId,
    ActingProcessName,
    ActingProcessCommandLine,
    RegistryKey,
    RegistryValue,
    RegistryValueType,
    RegistryValueData

Stage 5: `extend` (7 consecutive steps)

| 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), '\\'))

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`EventType`	in	`RegistryKeyCreated` transforms: `cased` `RegistryValueSet` transforms: `cased` corpus 4 (kusto 4)
`RegistryKey`	regex_match	`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`

Output fields

Fields the rule emits when it matches. Chronicle authors list these in the outcome block; they appear on the detection and $risk_score drives alerting. Sentinel / Defender XDR rules build them up through project / summarize / extend stages. Sentinel maps these into alert fields via entityMappings and customDetails; Defender XDR custom detections surface them as alert fields directly.

Field	Source
`ActingProcessCommandLine`	`project`
`ActingProcessId`	`project`
`ActingProcessName`	`project`
`ActorUsername`	`project`
`ActorUsernameType`	`project`
`DvcHostname`	`project`
`RegistryKey`	`project`
`RegistryValue`	`project`
`RegistryValueData`	`project`
`RegistryValueType`	`project`
`TimeGenerated`	`project`
`HostName`	`extend`
`DnsDomain`	`extend`
`Username`	`extend`
`NTDomain`	`extend`
`UPNSuffix`	`extend`
`RegHive`	`extend`
`RegKey`	`extend`

`j` / `k`	Scroll down / up
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`f`	Follow link (`Shift` = new tab)
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`?`	Toggle this help
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`Enter`	Open highlighted result
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`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)

Detect Print Processors Registry Driver Key Creation/Modification

MITRE ATT&CK coverage

Event coverage

Rule body kusto

Stages and Predicates

Let binding: `printProcessorRegistryRegEx`

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `project`

Stage 5: `extend` (7 consecutive steps)

Indicators

Output fields

Keyboard shortcuts

Search operators

Detect Print Processors Registry Driver Key Creation/Modification

MITRE ATT&CK coverage

Event coverage

Rule body kusto

Stages and Predicates

Let binding: printProcessorRegistryRegEx

Stage 1: source

Stage 2: where

Stage 3: where

Stage 4: project

Stage 5: extend (7 consecutive steps)

Indicators

Output fields

Let binding: `printProcessorRegistryRegEx`

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `project`

Stage 5: `extend` (7 consecutive steps)