M2131_AssetStoppedLogging

Status: available
Severity: medium
Time window: 14d
Group by: ResourceId
Source: github.com/Azure/Azure-Sentinel

'This alert is designed to monitor assets within the Maturity Model for Event Log Management (M-21-31) standard. The alert triggers when a monitored asset fails to provide a heartbeat within 24 hours.'

MITRE ATT&CK coverage

Tactic	Techniques
Discovery	`T1082` System Information Discovery

Rule body kusto

id: 4be5b645-1d08-49e4-b58d-07294ff19223
name: M2131_AssetStoppedLogging
description: |
  'This alert is designed to monitor assets within the Maturity Model for Event Log Management (M-21-31) standard. The alert triggers when a monitored asset fails to provide a heartbeat within 24 hours.'
severity: Medium
status: Available 
requiredDataConnectors: []
queryFrequency: 1d
queryPeriod: 14d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Discovery
relevantTechniques:
  - T1082
query: |
  let LastHeartbeatTime = Heartbeat
  | summarize LastHeartbeat_Time = arg_max(TimeGenerated, *) by ResourceId;
  Heartbeat
  | where TimeGenerated > ago(14d)
  | summarize LastHeartbeat_Hours = datetime_diff("hour",now(), max(TimeGenerated)) by ResourceId
  | where ResourceId <> ""
  | where ResourceId <> "None"
  | join kind=inner (LastHeartbeatTime) on ResourceId
  | where LastHeartbeat_Hours > 24
  | project LastHeartbeat_Hours, LastHeartbeat_Time, Computer, ComputerIP, Category, OSType, OSName, ResourceId, SubscriptionId, ResourceGroup, RemoteIPCountry 
  | sort by LastHeartbeat_Hours desc
entityMappings:
  - entityType: AzureResource
    fieldMappings:
      - identifier: ResourceId
        columnName: ResourceId
version: 1.0.0
kind: Scheduled

Stages and Predicates

Let binding: `LastHeartbeatTime`

let LastHeartbeatTime = Heartbeat
| summarize LastHeartbeat_Time = arg_max(TimeGenerated, *) by ResourceId;

Stage 1: `source`

Heartbeat

Stage 2: `where`

| where TimeGenerated > ago(14d)

Stage 3: `summarize`

| summarize LastHeartbeat_Hours = datetime_diff("hour",now(), max(TimeGenerated)) by ResourceId

Stage 4: `where`

| where ResourceId <> ""

Stage 5: `where`

| where ResourceId <> "None"

Stage 6: `join`

| join kind=inner (LastHeartbeatTime) on ResourceId

Stage 7: `where`

| where LastHeartbeat_Hours > 24

Stage 8: `project`

| project LastHeartbeat_Hours, LastHeartbeat_Time, Computer, ComputerIP, Category, OSType, OSName, ResourceId, SubscriptionId, ResourceGroup, RemoteIPCountry

Stage 9: `sort`

| sort by LastHeartbeat_Hours desc

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
`LastHeartbeat_Hours`	gt	`24` transforms: `cased`
`ResourceId`	ne	`None` transforms: `cased`

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
`Category`	`project`
`Computer`	`project`
`ComputerIP`	`project`
`LastHeartbeat_Hours`	`project`
`LastHeartbeat_Time`	`project`
`OSName`	`project`
`OSType`	`project`
`RemoteIPCountry`	`project`
`ResourceGroup`	`project`
`ResourceId`	`project`
`SubscriptionId`	`project`

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
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`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)

M2131_AssetStoppedLogging

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Let binding: `LastHeartbeatTime`

Stage 1: `source`

Stage 2: `where`

Stage 3: `summarize`

Stage 4: `where`

Stage 5: `where`

Stage 6: `join`

Stage 7: `where`

Stage 8: `project`

Stage 9: `sort`

Indicators

Output fields

Keyboard shortcuts

Search operators

M2131_AssetStoppedLogging

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Let binding: LastHeartbeatTime

Stage 1: source

Stage 2: where

Stage 3: summarize

Stage 4: where

Stage 5: where

Stage 6: join

Stage 7: where

Stage 8: project

Stage 9: sort

Indicators

Output fields

Let binding: `LastHeartbeatTime`

Stage 1: `source`

Stage 2: `where`

Stage 3: `summarize`

Stage 4: `where`

Stage 5: `where`

Stage 6: `join`

Stage 7: `where`

Stage 8: `project`

Stage 9: `sort`