TI map IP entity to Web Session Events (ASIM Web Session schema)

Severity: medium
Time window: 14d
Group by: DstIpAddr, IndicatorId, ObservableValue, SrcIpAddr, TI_ipEntity
Source: github.com/Azure/Azure-Sentinel

This rule identifies Web Sessions for which the source IP address is a known IoC. This rule uses the Advanced Security Information Model (ASIM) and supports any web session source that complies with ASIM.

MITRE ATT&CK coverage

Tactic	Techniques
Command & Control	`T1071` Application Layer Protocol

Rule body kusto

id: 0548be6c-135e-4eb6-b9ff-14a09df62c77
name: TI map IP entity to Web Session Events (ASIM Web Session schema)
description: |
  This rule identifies Web Sessions for which the source IP address is a known IoC. This rule uses the [Advanced Security Information Model (ASIM)](https://aka.ms/AboutASIM) and supports any web session source that complies with ASIM.
severity: Medium
requiredDataConnectors:
  - connectorId: SquidProxy
    dataTypes:
      - SquidProxy_CL
  - connectorId: Zscaler
    dataTypes:
      - CommonSecurityLog
  - connectorId: ThreatIntelligence
    dataTypes:
      - ThreatIntelIndicators
  - connectorId: ThreatIntelligenceTaxii
    dataTypes:
      - ThreatIntelIndicators
  - connectorId: MicrosoftDefenderThreatIntelligence
    dataTypes:
      - ThreatIntelIndicators
queryFrequency: 1h
queryPeriod: 14d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - CommandAndControl
relevantTechniques:
  - T1071
query: |
  let HAS_ANY_MAX = 10000;
  let dt_lookBack = 1h;
  let ioc_lookBack = 14d;
  let IP_TI = ThreatIntelIndicators
  //extract key part of kv pair
       | extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
       | where IndicatorType in ("ipv4-addr", "ipv6-addr", "network-traffic")
       | extend NetworkSourceIP = toupper(ObservableValue)
       | extend TrafficLightProtocolLevel = tostring(parse_json(AdditionalFields).TLPLevel)
    | where TimeGenerated >= ago(ioc_lookBack)
    // As there is potentially more than 1 indicator type for matching IP, taking NetworkIP first, then others if that is empty.
    // Taking the first non-empty value based on potential IOC match availability
    | extend TI_ipEntity = NetworkSourceIP
    // Picking up only IOC's that contain the entities we want
    | where TI_ipEntity != "NO_IP"
    // Exclude local addresses, using the ipv4_is_private operator
    | where ipv4_is_private(TI_ipEntity) == false and TI_ipEntity !startswith "fe80" and TI_ipEntity !startswith "::" and TI_ipEntity !startswith "127."
    | extend ThreatType = tostring(Data.indicator_types[0])
    | extend IndicatorId = tostring(split(Id, "--")[2])
    | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId, ObservableValue
    | where IsActive and (ValidUntil > now() or isempty(ValidUntil));
  let IP_TI_list = toscalar(IP_TI
    | summarize NIoCs = dcount(TI_ipEntity), IoCs = make_set(TI_ipEntity)
    | project IoCs = iff(NIoCs > HAS_ANY_MAX, dynamic([]), IoCs));
  IP_TI
     | project-reorder *, Tags, TrafficLightProtocolLevel, NetworkSourceIP, Type, TI_ipEntity
  // 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 (
      _Im_WebSession (starttime = ago(dt_lookBack), srcipaddr_has_any_prefix = IP_TI_list)
      | where isnotempty(SrcIpAddr)
      // renaming time column so it is clear the log this came from
      | extend imNWS_TimeGenerated = TimeGenerated
    )
    on $left.TI_ipEntity == $right.SrcIpAddr
  | where imNWS_TimeGenerated < ValidUntil
  | summarize imNWS_TimeGenerated = arg_max(imNWS_TimeGenerated, *) by IndicatorId, DstIpAddr
  | extend Description = tostring(parse_json(Data).description)
  | extend ActivityGroupNames = extract(@"ActivityGroup:(\S+)", 1, tostring(parse_json(Data).labels))
  | project imNWS_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, ValidUntil, Confidence, TI_ipEntity, Dvc, SrcIpAddr, DstIpAddr, Url
entityMappings:
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: DstIpAddr
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: SrcIpAddr
customDetails:
  EventTime: imNWS_TimeGenerated
  IoCDescription: Description
  ActivityGroupNames: ActivityGroupNames
  IndicatorId: IndicatorId
  ThreatType: ThreatType
  IoCExpirationTime: ValidUntil
  IoCConfidenceScore: Confidence
alertDetailsOverride:
  alertDisplayNameFormat: The IP {{SrcIpAddr}} of the web request matches an IP IoC
  alertDescriptionFormat: The source address {{SrcIpAddr}} of the web request for the URL {{Url}} matches a known indicator of compromise of {{ThreatType}}. Consult the threat intelligence feed for more information about the indicator.
version: 1.2.10
kind: Scheduled

Stages and Predicates

Parameters

let HAS_ANY_MAX = 10000;
let dt_lookBack = 1h;
let ioc_lookBack = 14d;

Let binding: `IP_TI_list`

let IP_TI_list = toscalar(IP_TI
  | summarize NIoCs = dcount(TI_ipEntity), IoCs = make_set(TI_ipEntity)
  | project IoCs = iff(NIoCs > HAS_ANY_MAX, dynamic([]), IoCs));

Derived from HAS_ANY_MAX, IP_TI.

The stages below define let IP_TI (the rule's main pipeline source).

Stage 1: `source`

ThreatIntelIndicators

Stage 2: `extend`

| extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))

Stage 3: `where`

| where IndicatorType in ("ipv4-addr", "ipv6-addr", "network-traffic")

Stage 4: `extend`

| extend NetworkSourceIP = toupper(ObservableValue)

Stage 5: `extend`

| extend TrafficLightProtocolLevel = tostring(parse_json(AdditionalFields).TLPLevel)

Stage 6: `where`

| where TimeGenerated >= ago(ioc_lookBack)

Stage 7: `extend`

| extend TI_ipEntity = NetworkSourceIP

Stage 8: `where`

| where TI_ipEntity != "NO_IP"

Stage 9: `where`

| where ipv4_is_private(TI_ipEntity) == false and TI_ipEntity !startswith "fe80" and TI_ipEntity !startswith "::" and TI_ipEntity !startswith "127."

Stage 10: `extend`

| extend ThreatType = tostring(Data.indicator_types[0])

Stage 11: `extend`

| extend IndicatorId = tostring(split(Id, "--")[2])

Stage 12: `summarize`

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

Stage 13: `where`

| where IsActive and (ValidUntil > now() or isempty(ValidUntil))

The stages below run on IP_TI (the outer pipeline).

Stage 14: `project-reorder`

IP_TI
| project-reorder *, Tags, TrafficLightProtocolLevel, NetworkSourceIP, Type, TI_ipEntity

Stage 15: `join`

| join kind = innerunique (
    _Im_WebSession (starttime = ago(dt_lookBack), srcipaddr_has_any_prefix = IP_TI_list)
    | where isnotempty(SrcIpAddr)
    | extend imNWS_TimeGenerated = TimeGenerated
  )
  on $left.TI_ipEntity == $right.SrcIpAddr

Stage 16: `where`

| where imNWS_TimeGenerated < ValidUntil

Stage 17: `summarize`

| summarize imNWS_TimeGenerated = arg_max(imNWS_TimeGenerated, *) by IndicatorId, DstIpAddr

Stage 18: `extend`

| extend Description = tostring(parse_json(Data).description)

Stage 19: `extend`

| extend ActivityGroupNames = extract(@"ActivityGroup:(\S+)", 1, tostring(parse_json(Data).labels))

Stage 20: `project`

| project imNWS_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, ValidUntil, Confidence, TI_ipEntity, Dvc, SrcIpAddr, DstIpAddr, Url

Exclusions

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

Field	Kind	Excluded values
`TI_ipEntity`	cidr_match	`10.0.0.0/8`, `172.16.0.0/12`, `192.168.0.0/16`, `169.254.0.0/16`, `127.0.0.0/8`
`TI_ipEntity`	starts_with	`127.`
`TI_ipEntity`	starts_with	`::`
`TI_ipEntity`	starts_with	`fe80`

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
`IndicatorType`	in	`ipv4-addr` transforms: `cased` `ipv6-addr` transforms: `cased` `network-traffic` transforms: `cased`
`SrcIpAddr`	is_not_null	(no value, null check)
`TI_ipEntity`	ne	`NO_IP` transforms: `cased`
`ValidUntil`	is_null	(no value, null check)
`imNWS_TimeGenerated`	lt	`ValidUntil` 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
`ActivityGroupNames`	`project`
`Confidence`	`project`
`Description`	`project`
`DstIpAddr`	`project`
`Dvc`	`project`
`IndicatorId`	`project`
`SrcIpAddr`	`project`
`TI_ipEntity`	`project`
`ThreatType`	`project`
`Url`	`project`
`ValidUntil`	`project`
`imNWS_TimeGenerated`	`project`

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`gg` / `G`	Top / bottom
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`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
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`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)

TI map IP entity to Web Session Events (ASIM Web Session schema)

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Parameters

Let binding: `IP_TI_list`

Stage 1: `source`

Stage 2: `extend`

Stage 3: `where`

Stage 4: `extend`

Stage 5: `extend`

Stage 6: `where`

Stage 7: `extend`

Stage 8: `where`

Stage 9: `where`

Stage 10: `extend`

Stage 11: `extend`

Stage 12: `summarize`

Stage 13: `where`

Stage 14: `project-reorder`

Stage 15: `join`

Stage 16: `where`

Stage 17: `summarize`

Stage 18: `extend`

Stage 19: `extend`

Stage 20: `project`

Exclusions

Indicators

Output fields

Keyboard shortcuts

Search operators

TI map IP entity to Web Session Events (ASIM Web Session schema)

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Parameters

Let binding: IP_TI_list

Stage 1: source

Stage 2: extend

Stage 3: where

Stage 4: extend

Stage 5: extend

Stage 6: where

Stage 7: extend

Stage 8: where

Stage 9: where

Stage 10: extend

Stage 11: extend

Stage 12: summarize

Stage 13: where

Stage 14: project-reorder

Stage 15: join

Stage 16: where

Stage 17: summarize

Stage 18: extend

Stage 19: extend

Stage 20: project

Exclusions

Indicators

Output fields

Let binding: `IP_TI_list`

Stage 1: `source`

Stage 2: `extend`

Stage 3: `where`

Stage 4: `extend`

Stage 5: `extend`

Stage 6: `where`

Stage 7: `extend`

Stage 8: `where`

Stage 9: `where`

Stage 10: `extend`

Stage 11: `extend`

Stage 12: `summarize`

Stage 13: `where`

Stage 14: `project-reorder`

Stage 15: `join`

Stage 16: `where`

Stage 17: `summarize`

Stage 18: `extend`

Stage 19: `extend`

Stage 20: `project`