PLC unsecure key state (Microsoft Defender for IoT)

Status: available
Severity: low
Time window: 3h
Source: github.com/Azure/Azure-Sentinel

'This alert leverages Defender for IoT to detect PLC operating mode changes indicating the PLC is potentially insecure. If the PLC is compromised, devices that interact with it may be impacted. This may affect overall system security and safety.'

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T0858` Change Operating Mode
Evasion	`T0858` Change Operating Mode

Rule body kusto

id: f9df500a-e2a4-4104-a517-dc1d85bb654f
name: PLC unsecure key state (Microsoft Defender for IoT)
description: |
  'This alert leverages Defender for IoT to detect PLC operating mode changes indicating the PLC is potentially insecure. If the PLC is compromised, devices that interact with it may be impacted. This may affect overall system security and safety.'
severity: Low
status: Available
requiredDataConnectors:
  - connectorId: IoT
    dataTypes:
      - SecurityAlert (ASC for IoT)
queryFrequency: 3h
queryPeriod: 3h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Execution
relevantTechniques:
  - T0858
query: |
  SecurityAlert
  | where ProviderName == "IoTSecurity"
  | where AlertName has "PLC Operating Mode Changed"
  | extend ExtendedProperties = parse_json(ExtendedProperties)
  | where tostring(ExtendedProperties.isNew) == "True"
  | extend DeviceId = tostring(ExtendedProperties.DeviceId), 
           SourceDeviceAddress = tostring(ExtendedProperties.SourceDeviceAddress), 
           DestDeviceAddress = tostring(ExtendedProperties.DestinationDeviceAddress), 
           RemediationSteps = tostring(parse_json(RemediationSteps)[0]), 
           Protocol = tostring(ExtendedProperties.Protocol), 
           AlertManagementUri = tostring(ExtendedProperties.AlertManagementUri)
  | project
    TimeGenerated,
    DeviceId,
    ProductName,
    ProductComponentName,
    AlertSeverity,
    AlertName,
    Description,
    Protocol,
    SourceDeviceAddress,
    DestDeviceAddress,
    RemediationSteps,
    Tactics,
    Entities,
    VendorOriginalId,
    AlertLink,
    AlertManagementUri,
    Techniques
entityMappings:
sentinelEntitiesMappings:
  - columnName: Entities
eventGroupingSettings:
  aggregationKind: AlertPerResult
customDetails:
  Sensor: DeviceId
  Protocol: Protocol
  VendorOriginalId: VendorOriginalId
  AlertManagementUri: AlertManagementUri
alertDetailsOverride:
  alertDisplayNameFormat: (MDIoT) {{AlertName}}
  alertDescriptionFormat: (MDIoT) {{Description}}
  alertTacticsColumnName: Tactics
  alertSeverityColumnName: AlertSeverity
  alertDynamicProperties: 
    - alertProperty: ProductName
      value: ProductName
    - alertProperty: RemediationSteps
      value: RemediationSteps
    - alertProperty: Techniques
      value: Techniques
    - alertProperty: ProductComponentName
      value: ProductComponentName
    - alertProperty: AlertLink
      value: AlertLink
version: 1.0.3
kind: Scheduled

Stages and Predicates

Stage 1: `source`

SecurityAlert

Stage 2: `where`

| where ProviderName == "IoTSecurity"

Stage 3: `where`

| where AlertName has "PLC Operating Mode Changed"

Stage 4: `extend`

| extend ExtendedProperties = parse_json(ExtendedProperties)

Stage 5: `where`

| where tostring(ExtendedProperties.isNew) == "True"

Stage 6: `extend`

| extend DeviceId = tostring(ExtendedProperties.DeviceId), 
         SourceDeviceAddress = tostring(ExtendedProperties.SourceDeviceAddress), 
         DestDeviceAddress = tostring(ExtendedProperties.DestinationDeviceAddress), 
         RemediationSteps = tostring(parse_json(RemediationSteps)[0]), 
         Protocol = tostring(ExtendedProperties.Protocol), 
         AlertManagementUri = tostring(ExtendedProperties.AlertManagementUri)

Stage 7: `project`

| project
  TimeGenerated,
  DeviceId,
  ProductName,
  ProductComponentName,
  AlertSeverity,
  AlertName,
  Description,
  Protocol,
  SourceDeviceAddress,
  DestDeviceAddress,
  RemediationSteps,
  Tactics,
  Entities,
  VendorOriginalId,
  AlertLink,
  AlertManagementUri,
  Techniques

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
`AlertName`	match	`PLC Operating Mode Changed` transforms: `term`
`ProviderName`	eq	`IoTSecurity` transforms: `cased` corpus 15 (kusto 15)
`isNew`	eq	`True` transforms: `tostring`, `cased` corpus 15 (kusto 15)

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
`AlertLink`	`project`
`AlertManagementUri`	`project`
`AlertName`	`project`
`AlertSeverity`	`project`
`Description`	`project`
`DestDeviceAddress`	`project`
`DeviceId`	`project`
`Entities`	`project`
`ProductComponentName`	`project`
`ProductName`	`project`
`Protocol`	`project`
`RemediationSteps`	`project`
`SourceDeviceAddress`	`project`
`Tactics`	`project`
`Techniques`	`project`
`TimeGenerated`	`project`
`VendorOriginalId`	`project`

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`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)

PLC unsecure key state (Microsoft Defender for IoT)

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `extend`

Stage 5: `where`

Stage 6: `extend`

Stage 7: `project`

Indicators

Output fields

Keyboard shortcuts

Search operators

PLC unsecure key state (Microsoft Defender for IoT)

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Stage 1: source

Stage 2: where

Stage 3: where

Stage 4: extend

Stage 5: where

Stage 6: extend

Stage 7: project

Indicators

Output fields

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `extend`

Stage 5: `where`

Stage 6: `extend`

Stage 7: `project`