Vectra AI Detect - Suspected Compromised Host

Status: available
Severity: informational
Time window: 5m
Group by: SourceHostName
Source: github.com/Azure/Azure-Sentinel

'Create an incident when a Host is suspected to be compromised. The higher the severity level is, the more immediate attention it requires as Vectra AI engine is more confident that this is a real threat. Level of severity are: Low, Medium, High, Critical). Recommended configuration is to trigger an alert for at least High and Critical.'

MITRE ATT&CK coverage

Tactic	Techniques
Credential Access	`T1003` OS Credential Dumping
Discovery	`T1087` Account Discovery
Lateral Movement	`T1021` Remote Services
Collection	`T1119` Automated Collection
Command & Control	`T1071` Application Layer Protocol
Exfiltration	`T1041` Exfiltration Over C2 Channel
Impact	`T1499` Endpoint Denial of Service

Rule body kusto

id: 60eb6cf0-3fa1-44c1-b1fe-220fbee23d63
name: Vectra AI Detect - Suspected Compromised Host
description: |
  'Create an incident when a Host is suspected to be compromised. 
  The higher the severity level is, the more immediate attention it requires as Vectra AI engine is more confident that this is a real threat. 
  Level of severity are: Low, Medium, High, Critical). Recommended configuration is to trigger an alert for at least High and Critical.'
severity: Informational
status: Available
requiredDataConnectors:
  - connectorId: CefAma
    dataTypes:
      - CommonSecurityLog
queryFrequency: 5m
queryPeriod: 5m
triggerOperator: gt
triggerThreshold: 0
eventGroupingSettings:
  aggregationKind: AlertPerResult
tactics:
  - CredentialAccess
  - Discovery
  - LateralMovement
  - Collection
  - CommandAndControl
  - Exfiltration
  - Impact
relevantTechniques:
  - T1003
  - T1087
  - T1021
  - T1119
  - T1071
  - T1041
  - T1499
query: |
  // Edit this variable to only keep the Severity level where an incident needs to be created (Defaults are: "High", "Critical" ). Possible values are: "Low", "Medium", "High", "Critical"
  let configured_level = dynamic(["High", "Critical"]);
  CommonSecurityLog
  | where DeviceVendor == "Vectra Networks"
  | where DeviceProduct == "X Series"
  | where DeviceEventClassID == "hsc"
  | project-rename threat_score = FlexNumber1
  | project-rename certainty_score = FlexNumber2
  | project-rename vectra_URL = DeviceCustomString4
  | project-rename detection_name = DeviceEventClassID
  | project-rename score_decreases = DeviceCustomString3
  | extend level = case( threat_score <  50 and certainty_score < 50, "Low",
                        threat_score < 50 and certainty_score >= 50 , "Medium", 
                        threat_score >= 50 and certainty_score <= 50, "High", 
                        threat_score >= 50 and certainty_score >= 50, "Critical",
                        "UNKNOWN")
  | extend Severity = case(level == "Info", "Informational",level == "Critical", "High", level)
  | where level in (configured_level) 
  //keep only the event with the highest threat score per Host
  | summarize arg_max(TimeGenerated, *) by SourceHostName
  | sort by TimeGenerated
entityMappings:
  - entityType: Host
    fieldMappings:
      - identifier: HostName
        columnName: SourceHostName
alertDetailsOverride:
  alertDisplayNameFormat: Vectra AI Detect - Host {{SourceHostName}} reaches {{level}} severity
  alertDescriptionFormat: |
    The host {{SourceHostName}} has a Threat score of {{threat_score}} and a
    certainty of {{certainty_score}}
  alertSeverityColumnName: Severity
  alertDynamicProperties:
    - alertProperty: AlertLink
      value: vectra_URL
    - alertProperty: ProductName
      value: DeviceProduct
    - alertProperty: ProviderName
      value: DeviceVendor
    - alertProperty: ConfidenceScore
      value: certainty_score
incidentConfiguration:
  createIncident: true
  groupingConfiguration:
    enabled: true
    reopenClosedIncident: true
    lookbackDuration: 7d
    matchingMethod: AllEntities
customDetails:
  ScoreDecrease: score_decreases
version: 1.0.9
kind: Scheduled

Stages and Predicates

Parameters

let configured_level = dynamic(["High", "Critical"]);

Stage 1: `source`

CommonSecurityLog

Stage 2: `where`

| where DeviceVendor == "Vectra Networks"

Stage 3: `where`

| where DeviceProduct == "X Series"

Stage 4: `where`

| where DeviceEventClassID == "hsc"

Stage 5: `project-rename`

| project-rename threat_score = FlexNumber1

Stage 6: `project-rename`

| project-rename certainty_score = FlexNumber2

Stage 7: `project-rename`

| project-rename vectra_URL = DeviceCustomString4

Stage 8: `project-rename`

| project-rename detection_name = DeviceEventClassID

Stage 9: `project-rename`

| project-rename score_decreases = DeviceCustomString3

Stage 10: `extend`

| extend level = case( threat_score <  50 and certainty_score < 50, "Low",
                      threat_score < 50 and certainty_score >= 50 , "Medium", 
                      threat_score >= 50 and certainty_score <= 50, "High", 
                      threat_score >= 50 and certainty_score >= 50, "Critical",
                      "UNKNOWN")

level =

ifthreat_score < 50 and certainty_score < 50"Low"

elifthreat_score < 50 and certainty_score >= 50"Medium"

elifthreat_score >= 50 and certainty_score <= 50"High"

elifthreat_score >= 50 and certainty_score >= 50"Critical"

else"UNKNOWN"

Stage 11: `extend`

| extend Severity = case(level == "Info", "Informational",level == "Critical", "High", level)

Severity =

iflevel == "Info""Informational"

eliflevel == "Critical""High"

elselevel

Stage 12: `where`

| where level in (configured_level)

Stage 13: `summarize`

| summarize arg_max(TimeGenerated, *) by SourceHostName

Stage 14: `sort`

| sort by TimeGenerated

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
`DeviceEventClassID`	eq	`hsc` transforms: `cased`
`DeviceProduct`	eq	`X Series` transforms: `cased`
`DeviceVendor`	eq	`Vectra Networks` transforms: `cased`
`level`	in	`Critical` transforms: `cased` `High` 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
`SourceHostName`	`summarize`

`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)

Vectra AI Detect - Suspected Compromised Host

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Parameters

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `where`

Stage 5: `project-rename`

Stage 6: `project-rename`

Stage 7: `project-rename`

Stage 8: `project-rename`

Stage 9: `project-rename`

Stage 10: `extend`

Stage 11: `extend`

Stage 12: `where`

Stage 13: `summarize`

Stage 14: `sort`

Indicators

Output fields

Keyboard shortcuts

Search operators

Vectra AI Detect - Suspected Compromised Host

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Parameters

Stage 1: source

Stage 2: where

Stage 3: where

Stage 4: where

Stage 5: project-rename

Stage 6: project-rename

Stage 7: project-rename

Stage 8: project-rename

Stage 9: project-rename

Stage 10: extend

Stage 11: extend

Stage 12: where

Stage 13: summarize

Stage 14: sort

Indicators

Output fields

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `where`

Stage 5: `project-rename`

Stage 6: `project-rename`

Stage 7: `project-rename`

Stage 8: `project-rename`

Stage 9: `project-rename`

Stage 10: `extend`

Stage 11: `extend`

Stage 12: `where`

Stage 13: `summarize`

Stage 14: `sort`