TI map Email entity to SecurityEvent

Severity: medium
Time window: 14d
Group by: EmailSenderAddress, IndicatorId, TargetUserName
Source: github.com/Azure/Azure-Sentinel

'Identifies a match in SecurityEvent table from any Email IOC from TI'

MITRE ATT&CK coverage

Tactic	Techniques
Initial Access	`T1566` Phishing

Rule body kusto

id: 2fc5d810-c9cc-491a-b564-841427ae0e50
name: TI map Email entity to SecurityEvent
description: |
  'Identifies a match in SecurityEvent table from any Email IOC from TI'
severity: Medium
requiredDataConnectors:
  - connectorId: ThreatIntelligence
    dataTypes:
      - ThreatIntelligenceIndicator
  - connectorId: ThreatIntelligenceTaxii
    dataTypes:
      - ThreatIntelligenceIndicator
  - connectorId: SecurityEvents
    dataTypes:
      - SecurityEvent
  - connectorId: WindowsSecurityEvents
    dataTypes:
      - SecurityEvents
  - connectorId: WindowsForwardedEvents
    dataTypes:
      - WindowsEvent
  - connectorId: MicrosoftDefenderThreatIntelligence
    dataTypes:
      - ThreatIntelligenceIndicator
queryFrequency: 1h
queryPeriod: 14d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - InitialAccess
relevantTechniques:
  - T1566
query: |
  let dt_lookBack = 1h;
  let ioc_lookBack = 14d;
  let emailregex = @'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$';
  ThreatIntelligenceIndicator
  //Filtering the table for Email related IOCs
  | where isnotempty(EmailSenderAddress)
  | where TimeGenerated >= ago(ioc_lookBack)
  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
  | where Active == true and ExpirationDateTime > now()
  // using innerunique to keep perf fast and result set low, we only need one match to indicate potential malicious activity that needs to be investigated
  | join kind=innerunique (
  (union isfuzzy=true
  (SecurityEvent
  | where TimeGenerated >= ago(dt_lookBack) and isnotempty(TargetUserName)
  //Normalizing the column to lower case for exact match with EmailSenderAddress column
  | extend TargetUserName = tolower(TargetUserName)
  // renaming timestamp column so it is clear the log this came from SecurityEvent table
  | extend SecurityEvent_TimeGenerated = TimeGenerated
  ),
  (WindowsEvent
  | where TimeGenerated >= ago(dt_lookBack)
  | extend TargetUserName = tostring(EventData.TargetUserName)
  | where isnotempty(TargetUserName)
  //Normalizing the column to lower case for exact match with EmailSenderAddress column
  | extend TargetUserName = tolower(TargetUserName)
  // renaming timestamp column so it is clear the log this came from SecurityEvent table
  | extend SecurityEvent_TimeGenerated = TimeGenerated
  ))
  )
  on $left.EmailSenderAddress == $right.TargetUserName
  | where SecurityEvent_TimeGenerated < ExpirationDateTime
  | summarize SecurityEvent_TimeGenerated = arg_max(SecurityEvent_TimeGenerated, *) by IndicatorId, TargetUserName
  | project SecurityEvent_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, Url, ExpirationDateTime, ConfidenceScore,
  EmailSenderName, EmailRecipient, EmailSourceDomain, EmailSourceIpAddress, EmailSubject, FileHashValue, FileHashType, Computer, EventID, TargetUserName, Activity, IpAddress, AccountType,
  LogonTypeName, LogonProcessName, Status, SubStatus
  | extend HostName = tostring(split(Computer, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Computer, '.'), 1, -1), '.'))
  | extend timestamp = SecurityEvent_TimeGenerated
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: Name
        columnName: TargetUserName
  - entityType: Host
    fieldMappings:
      - identifier: HostName
        columnName: HostName
      - identifier: DnsDomain
        columnName: DnsDomain   
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: IpAddress
  - entityType: URL
    fieldMappings:
      - identifier: Url
        columnName: Url
version: 1.3.6
kind: Scheduled

Stages and Predicates

Parameters

let dt_lookBack = 1h;
let ioc_lookBack = 14d;
let emailregex = @'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$';

Stage 1: `source`

ThreatIntelligenceIndicator

Stage 2: `where`

| where isnotempty(EmailSenderAddress)

Stage 3: `where`

| where TimeGenerated >= ago(ioc_lookBack)

Stage 4: `summarize`

| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId

Stage 5: `where`

| where Active == true and ExpirationDateTime > now()

Stage 6: `join`

| join kind=innerunique (
(union isfuzzy=true
(SecurityEvent
| where TimeGenerated >= ago(dt_lookBack) and isnotempty(TargetUserName)
| extend TargetUserName = tolower(TargetUserName)
| extend SecurityEvent_TimeGenerated = TimeGenerated
),
(WindowsEvent
| where TimeGenerated >= ago(dt_lookBack)
| extend TargetUserName = tostring(EventData.TargetUserName)
| where isnotempty(TargetUserName)
| extend TargetUserName = tolower(TargetUserName)
| extend SecurityEvent_TimeGenerated = TimeGenerated
))
)
on $left.EmailSenderAddress == $right.TargetUserName

Stage 7: `where`

| where SecurityEvent_TimeGenerated < ExpirationDateTime

Stage 8: `summarize`

| summarize SecurityEvent_TimeGenerated = arg_max(SecurityEvent_TimeGenerated, *) by IndicatorId, TargetUserName

Stage 9: `project`

| project SecurityEvent_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, Url, ExpirationDateTime, ConfidenceScore,
EmailSenderName, EmailRecipient, EmailSourceDomain, EmailSourceIpAddress, EmailSubject, FileHashValue, FileHashType, Computer, EventID, TargetUserName, Activity, IpAddress, AccountType,
LogonTypeName, LogonProcessName, Status, SubStatus

Stage 10: `extend`

| extend HostName = tostring(split(Computer, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Computer, '.'), 1, -1), '.'))

Stage 11: `extend`

| extend timestamp = SecurityEvent_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
`Active`	eq	`true` transforms: `cased` corpus 68 (kusto 68)
`EmailSenderAddress`	is_not_null	(no value, null check)
`SecurityEvent_TimeGenerated`	lt	`ExpirationDateTime` transforms: `cased` corpus 2 (kusto 2)
`TargetUserName`	is_not_null	(no value, null check)

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
`AccountType`	`project`
`Activity`	`project`
`ActivityGroupNames`	`project`
`Computer`	`project`
`ConfidenceScore`	`project`
`Description`	`project`
`EmailRecipient`	`project`
`EmailSenderName`	`project`
`EmailSourceDomain`	`project`
`EmailSourceIpAddress`	`project`
`EmailSubject`	`project`
`EventID`	`project`
`ExpirationDateTime`	`project`
`FileHashType`	`project`
`FileHashValue`	`project`
`IndicatorId`	`project`
`IpAddress`	`project`
`LogonProcessName`	`project`
`LogonTypeName`	`project`
`SecurityEvent_TimeGenerated`	`project`
`Status`	`project`
`SubStatus`	`project`
`TargetUserName`	`project`
`ThreatType`	`project`
`Url`	`project`
`DnsDomain`	`extend`
`HostName`	`extend`
`timestamp`	`extend`

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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)

TI map Email entity to SecurityEvent

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Parameters

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `summarize`

Stage 5: `where`

Stage 6: `join`

Stage 7: `where`

Stage 8: `summarize`

Stage 9: `project`

Stage 10: `extend`

Stage 11: `extend`

Indicators

Output fields

Keyboard shortcuts

Search operators

TI map Email entity to SecurityEvent

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Parameters

Stage 1: source

Stage 2: where

Stage 3: where

Stage 4: summarize

Stage 5: where

Stage 6: join

Stage 7: where

Stage 8: summarize

Stage 9: project

Stage 10: extend

Stage 11: extend

Indicators

Output fields

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `summarize`

Stage 5: `where`

Stage 6: `join`

Stage 7: `where`

Stage 8: `summarize`

Stage 9: `project`

Stage 10: `extend`

Stage 11: `extend`