Red Sift - New email with URL from previously unseen source

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

'Detects email forensics events that contain one or more URLs where the sender is using a source IP address not seen in the previous 14 days, which may indicate suspicious infrastructure changes or phishing activity.'

MITRE ATT&CK coverage

Tactic	Techniques
Initial Access	`T1566` Phishing

Rule body kusto

id: 6084dfd8-830b-4839-9a9c-5f08cc984729
name: Red Sift - New email with URL from previously unseen source
description: |
  'Detects email forensics events that contain one or more URLs where the sender is using a source IP address not seen in the previous 14 days, which may indicate suspicious infrastructure changes or phishing activity.'
severity: Medium
status: Available
requiredDataConnectors:
  - connectorId: RedSiftPush
    dataTypes:
      - RedSiftEmailForensics_CL
queryFrequency: 1h
queryPeriod: 14d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - InitialAccess
relevantTechniques:
  - T1566
query: |
  let lookback = 14d;
  let recentWindow = 1h;
  let historicalSources = RedSiftEmailForensics_CL
  | extend
      EmailFrom = tostring(column_ifexists("EmailFrom", "")),
      SrcIp = tostring(column_ifexists("SrcIp", ""))
  | where TimeGenerated between (ago(lookback) .. ago(recentWindow))
  | where isnotempty(EmailFrom) and isnotempty(SrcIp)
  | summarize by EmailFrom, SrcIp;
  RedSiftEmailForensics_CL
  | extend
      EmailFrom = tostring(column_ifexists("EmailFrom", "")),
      EmailSubject = tostring(column_ifexists("EmailSubject", "")),
      EmailReturnPath = tostring(column_ifexists("EmailReturnPath", "")),
      EmailMessageUid = tostring(column_ifexists("EmailMessageUid", "")),
      SrcIp = tostring(column_ifexists("SrcIp", "")),
      DstHostname = tostring(column_ifexists("DstHostname", "")),
      Severity = tostring(column_ifexists("Severity", "")),
      Message = tostring(column_ifexists("Message", "")),
      CorrelationUid = tostring(column_ifexists("CorrelationUid", "")),
      EmailUrls = todynamic(column_ifexists("EmailUrls", "[]"))
  | where TimeGenerated >= ago(recentWindow)
  | where isnotempty(EmailFrom) and isnotempty(SrcIp)
  | extend UrlCount = array_length(EmailUrls)
  | where UrlCount > 0
  | mv-apply Url = EmailUrls on (
      summarize UrlSet = make_set(tostring(Url.url_string), 50)
    )
  | extend UrlList = strcat_array(UrlSet, ", ")
  | join kind=leftanti (historicalSources) on EmailFrom, SrcIp
  | project
      TimeGenerated,
      EmailFrom,
      EmailSubject,
      EmailReturnPath,
      EmailMessageUid,
      SrcIp,
      DstHostname,
      UrlCount,
      UrlList,
      Severity,
      Message,
      CorrelationUid
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: EmailFrom
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: SrcIp
  - entityType: DNS
    fieldMappings:
      - identifier: DomainName
        columnName: DstHostname
customDetails:
  EmailSubject: EmailSubject
  ReturnPath: EmailReturnPath
  UrlCount: UrlCount
  UrlList: UrlList
  CorrelationUid: CorrelationUid
alertDetailsOverride:
  alertDisplayNameFormat: "RedSift - New URL-bearing email source for {{EmailFrom}}"
  alertDescriptionFormat: "Email from {{EmailFrom}} contains {{UrlCount}} URL(s) and originated from previously unseen source IP {{SrcIp}}."
incidentConfiguration:
  createIncident: true
  groupingConfiguration:
    enabled: true
    reopenClosedIncident: false
    lookbackDuration: P1D
    matchingMethod: Selected
    groupByEntities:
      - Account
      - IP
    groupByCustomDetails:
      - EmailSubject
eventGroupingSettings:
  aggregationKind: AlertPerResult
suppressionEnabled: false
suppressionDuration: PT1H
version: 1.0.0
kind: Scheduled

Stages and Predicates

Parameters

let lookback = 14d;
let recentWindow = 1h;

Let binding: `historicalSources`

let historicalSources = RedSiftEmailForensics_CL
| extend
    EmailFrom = tostring(column_ifexists("EmailFrom", "")),
    SrcIp = tostring(column_ifexists("SrcIp", ""))
| where TimeGenerated between (ago(lookback) .. ago(recentWindow))
| where isnotempty(EmailFrom) and isnotempty(SrcIp)
| summarize by EmailFrom, SrcIp;

Derived from lookback, recentWindow.

Stage 1: `source`

RedSiftEmailForensics_CL

Stage 2: `extend`

| extend
    EmailFrom = tostring(column_ifexists("EmailFrom", "")),
    EmailSubject = tostring(column_ifexists("EmailSubject", "")),
    EmailReturnPath = tostring(column_ifexists("EmailReturnPath", "")),
    EmailMessageUid = tostring(column_ifexists("EmailMessageUid", "")),
    SrcIp = tostring(column_ifexists("SrcIp", "")),
    DstHostname = tostring(column_ifexists("DstHostname", "")),
    Severity = tostring(column_ifexists("Severity", "")),
    Message = tostring(column_ifexists("Message", "")),
    CorrelationUid = tostring(column_ifexists("CorrelationUid", "")),
    EmailUrls = todynamic(column_ifexists("EmailUrls", "[]"))

Stage 3: `where`

| where TimeGenerated >= ago(recentWindow)

Stage 4: `where`

| where isnotempty(EmailFrom) and isnotempty(SrcIp)

Stage 5: `extend`

| extend UrlCount = array_length(EmailUrls)

Stage 6: `where`

| where UrlCount > 0

Stage 7: `kusto:mv-apply`

| mv-apply Url = EmailUrls on (
    summarize UrlSet = make_set(tostring(Url.url_string), 50)
  )

Stage 8: `extend`

| extend UrlList = strcat_array(UrlSet, ", ")

Stage 9: `join` (negated)

| join kind=leftanti (historicalSources) on EmailFrom, SrcIp

Stage 10: `project`

| project
    TimeGenerated,
    EmailFrom,
    EmailSubject,
    EmailReturnPath,
    EmailMessageUid,
    SrcIp,
    DstHostname,
    UrlCount,
    UrlList,
    Severity,
    Message,
    CorrelationUid

Stage 11: `summarize`

summarize

Stage 12: `summarize`

summarize by EmailFrom, SrcIp

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

Field	Kind	Excluded values
`EmailFrom`	is_not_null	(no value, null check)
`SrcIp`	is_not_null	(no value, null check)

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
`EmailFrom`	is_not_null	(no value, null check)
`SrcIp`	is_not_null	(no value, null check)
`UrlCount`	gt	`0` 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
`EmailFrom`	`summarize`
`SrcIp`	`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)

Red Sift - New email with URL from previously unseen source

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Parameters

Let binding: `historicalSources`

Stage 1: `source`

Stage 2: `extend`

Stage 3: `where`

Stage 4: `where`

Stage 5: `extend`

Stage 6: `where`

Stage 7: `kusto:mv-apply`

Stage 8: `extend`

Stage 9: `join` (negated)

Stage 10: `project`

Stage 11: `summarize`

Stage 12: `summarize`

Exclusions

Indicators

Output fields

Keyboard shortcuts

Search operators

Red Sift - New email with URL from previously unseen source

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Parameters

Let binding: historicalSources

Stage 1: source

Stage 2: extend

Stage 3: where

Stage 4: where

Stage 5: extend

Stage 6: where

Stage 7: kusto:mv-apply

Stage 8: extend

Stage 9: join (negated)

Stage 10: project

Stage 11: summarize

Stage 12: summarize

Exclusions

Indicators

Output fields

Let binding: `historicalSources`

Stage 1: `source`

Stage 2: `extend`

Stage 3: `where`

Stage 4: `where`

Stage 5: `extend`

Stage 6: `where`

Stage 7: `kusto:mv-apply`

Stage 8: `extend`

Stage 9: `join` (negated)

Stage 10: `project`

Stage 11: `summarize`

Stage 12: `summarize`