Detect port misuse by static threshold (ASIM Network Session schema)

Status: available
Severity: medium
Time window: 1h
Group by: Description, DstPortNumber, DvcAction, Name, NetworkCustomAnalyticsExists, NetworkDirection, NetworkProtocol, NetworkSummary_Protocol_Exists, Severity, Tactic, exists
Source: github.com/Azure/Azure-Sentinel

This detection rule detects port usage above the configured threshold. The rule utilize ASIM normalization, and is applied to any source which supports the ASIM Network Session schema. To tune the rule to your environment configure it using the 'NetworkSession_Monitor_Configuration' watchlist. This rule leverages log summaries generated by a Summary Rule or Summarized Playbook. If no such summaries are available, the rule falls back to direct analysis using ASIM function.

MITRE ATT&CK coverage

Tactic	Techniques
Initial Access	`T1190` Exploit Public-Facing Application
Execution	`T1059` Command and Scripting Interpreter `T1203` Exploitation for Client Execution
Command & Control	`T1095` Non-Application Layer Protocol

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 3: Network connection
Security-Auditing	Event ID 5152: The Windows Filtering Platform blocked a packet.
Security-Auditing	Event ID 5154: The Windows Filtering Platform has permitted an application or service to listen on a port for incoming connections.
Security-Auditing	Event ID 5155: The Windows Filtering Platform has blocked an application or service from listening on a port for incoming connections.
Security-Auditing	Event ID 5156: The Windows Filtering Platform has permitted a connection.
Security-Auditing	Event ID 5157: The Windows Filtering Platform has blocked a connection.
Security-Auditing	Event ID 5158: The Windows Filtering Platform has permitted a bind to a local port.
Security-Auditing	Event ID 5159: The Windows Filtering Platform has blocked a bind to a local port.

Rule body

id: 156997bd-da0f-4729-b47a-0a3e02dd50c8
name: Detect port misuse by static threshold (ASIM Network Session schema)
description: |
  'This detection rule detects port usage above the configured threshold. The rule utilize [ASIM](https://aka.ms/AboutASIM) normalization, and is applied to any source which supports the ASIM Network Session schema. To tune the rule to your environment configure it using the 'NetworkSession_Monitor_Configuration' watchlist. This rule leverages log summaries generated by a Summary Rule or Summarized Playbook. If no such summaries are available, the rule falls back to direct analysis using ASIM function.'
severity: Medium
status: Available
tags:
  - Schema: ASimNetworkSessions
    SchemaVersion: 0.2.4
requiredDataConnectors:
  - connectorId: AWSS3
    dataTypes:
      - AWSVPCFlow
  - connectorId: MicrosoftThreatProtection
    dataTypes:
      - DeviceNetworkEvents
  - connectorId: SecurityEvents
    dataTypes:
      - SecurityEvent
  - connectorId: WindowsSecurityEvents
    dataTypes:
      - SecurityEvent
  - connectorId: WindowsForwardedEvents
    dataTypes:
      - WindowsEvent
  - connectorId: Zscaler
    dataTypes:
      - CommonSecurityLog
  - connectorId: MicrosoftSysmonForLinux
    dataTypes:
      - Syslog
  - connectorId: PaloAltoNetworks
    dataTypes:
      - CommonSecurityLog
  - connectorId: AzureMonitor(VMInsights)
    dataTypes:
      - VMConnection
  - connectorId: AzureFirewall
    dataTypes:
      - AzureDiagnostics
  - connectorId: AzureNSG
    dataTypes:
      - AzureDiagnostics
  - connectorId: CiscoASA
    dataTypes:
      - CommonSecurityLog
  - connectorId: CiscoAsaAma
    dataTypes:
      - CommonSecurityLog
  - connectorId: Corelight
    dataTypes:
      - Corelight_CL
  - connectorId: AIVectraStream
    dataTypes:
      - VectraStream
  - connectorId: CheckPoint
    dataTypes:
      - CommonSecurityLog
  - connectorId: Fortinet
    dataTypes:
      - CommonSecurityLog
  - connectorId: CiscoMeraki
    dataTypes:
      - Syslog
      - CiscoMerakiNativePoller

queryFrequency: 20m
queryPeriod: 60m
triggerOperator: gt
triggerThreshold: 0
tactics:
  - CommandAndControl
  - Execution
  - InitialAccess
relevantTechniques:
  - T1095  
  - T1059
  - T1203
  - T1190
query: |
  let lookback = 20m; 
  let mapping = _GetWatchlist('NetworkSession_Monitor_Configuration')
      | where Type == "Detection" and ThresholdType == "Static" and Severity != "Disabled"  
      | extend
          Ports = split(Ports, ","),
          App = split(App, ","),
          Protocol = split(Protocol, ","),
          Direction = split(Direction, ","),
          Action = split(Action, ",")
      | project
          Ports,
          App,
          Protocol,
          Direction,
          Action,
          Type,
          ThresholdType,
          Threshold,
          Severity,
          Tactic,
          Name,
          Description
      | mv-expand Ports
      | mv-expand App
      | mv-expand Protocol
      | mv-expand Direction
      | mv-expand Action
      | extend
          Ports = tostring(Ports),
          App = tostring(App),
          Protocol = tostring(Protocol),
          Direction = tostring(Direction),
          Action = tostring(Action),
          Threshold = toint(Threshold);
  let NetworkSummary_Protocol = materialize(
      union isfuzzy=true 
          (
          NetworkSummary_Protocol_CL
          | project v = int(2)
          ),
          (
          print int(1) 
          | project v = print_0
          )
      | summarize maxv = max(v)
      | extend
          NetworkSummary_Protocol_Exists = (maxv > 1),
          NetworkCustomAnalyticsExists = false
      );
  let NetworkCustomAnalytics = materialize(
      union isfuzzy=true 
          (
          NetworkCustomAnalytics_protocol_CL
          | project v = int(2)
          ),
          (
          print int(1) 
          | project v = print_0
          )
      | summarize maxv = max(v)
      | extend
          NetworkCustomAnalyticsExists = (maxv > 1),
          NetworkSummary_Protocol_Exists = false
      );
  let allData = union isfuzzy=true 
          (
          (datatable(
      exists: int,
      NetworkSummary_Protocol_Exists: bool,
      NetworkCustomAnalyticsExists: bool
  )[
      1, false, false
  ]
          | join (NetworkSummary_Protocol) on NetworkSummary_Protocol_Exists
          | join (NetworkCustomAnalytics) on NetworkCustomAnalyticsExists
          )
          | join (
              _Im_NetworkSession(starttime=bin(now(-20m), 20m), endtime=bin(now(), 20m))
              | where TimeGenerated > bin(now(-20m), 20m)
              | summarize Count=count()
                  by
                  NetworkProtocol,
                  DstPortNumber,
                  DstAppName,
                  NetworkDirection,
                  DvcAction,
                  bin(TimeGenerated, 20m)
              | extend
                  EventTime = TimeGenerated,
                  Count = toint(Count),
                  DstPortNumber = toint(DstPortNumber),
                  exists=int(1)
              )
              on exists
          | project-away exists*, maxv, NetworkSummary_Protocol_Exists*, NetworkCustomAnalyticsExists*
          ),
          (
          (datatable(exists: int, NetworkSummary_Protocol_Exists: bool)[1, false]
          | join (NetworkSummary_Protocol) on NetworkSummary_Protocol_Exists
          )
          | join (
              NetworkCustomAnalytics_protocol_CL
              | where EventTime_t == toscalar(NetworkCustomAnalytics_protocol_CL
                  | summarize max(EventTime_t))
              | project
                  NetworkProtocol=NetworkProtocol_s,
                  DstPortNumber=DstPortNumber_d,
                  DstAppName=DstAppName_s,
                  NetworkDirection=NetworkDirection_s,
                  DvcAction=DvcAction_s,
                  Count=count__d,
                  EventTime=EventTime_t,
                  TimeGenerated,
                  Type
              | extend Count = toint(Count), DstPortNumber = toint(DstPortNumber), exists=int(1)
              )
              on exists
          | project-away exists*, maxv, NetworkSummary_Protocol_Exists*, NetworkCustomAnalyticsExists*
          ),
          (
          NetworkSummary_Protocol_CL
          | where EventTime == toscalar(NetworkSummary_Protocol_CL
              | summarize max(EventTime))
          | project
              NetworkProtocol,
              DstPortNumber,
              DstAppName,
              NetworkDirection,
              DvcAction,
              Count=count_,
              EventTime,
              TimeGenerated,
              Type
          | extend Count = toint(Count), DstPortNumber = toint(DstPortNumber)
          )
      | project-away exists*, maxv*, NetworkSummary_Protocol_Exists*, NetworkCustomAnalyticsExists*
  ;
  allData
  | where isnotempty(DstPortNumber)
  | summarize Sum=sum(Count) by DstPortNumber, NetworkProtocol, NetworkDirection, DvcAction 
  | join kind=inner ['mapping'] where Ports has tostring(DstPortNumber)
  | where Sum > Threshold         
      and (Protocol == "*" or Protocol has NetworkProtocol)
      and (Direction == "*" or Direction has NetworkDirection)
      and (Action == "*" or Action has DvcAction)
  | project
      Name,
      Description,
      NetworkProtocol,
      DstPortNumber,
      NetworkDirection,
      DvcAction,
      Severity,
      Tactic
  | summarize
      NetworkProtocols=make_set_if(NetworkProtocol, isnotempty(NetworkProtocol), 20), 
      NetworkDirections=make_set_if(NetworkDirection, isnotempty(NetworkDirection), 5), 
      DvcActions=make_set_if(DvcAction, isnotempty(DvcAction), 10)
      by Name, Severity, Tactic, DstPortNumber, Description
eventGroupingSettings:
  aggregationKind: AlertPerResult
customDetails:
  AllNetworkProtocols: NetworkProtocols
  AllNetworkDirections: NetworkDirections
  AllDvcAction: DvcActions
  DstPortNumber: DstPortNumber

alertDetailsOverride:
  alertDisplayNameFormat: Detected {{Name}}
  alertDescriptionFormat: '{{Description}}'
  alertTacticsColumnName: Tactic
  alertSeverityColumnName: Severity
version: 1.2.0
kind: Scheduled

Stages and Predicates

Parameters

let lookback = 20m;

Let binding: `mapping`

let mapping = _GetWatchlist('NetworkSession_Monitor_Configuration')
    | where Type == "Detection" and ThresholdType == "Static" and Severity != "Disabled"  
    | extend
        Ports = split(Ports, ","),
        App = split(App, ","),
        Protocol = split(Protocol, ","),
        Direction = split(Direction, ","),
        Action = split(Action, ",")
    | project
        Ports,
        App,
        Protocol,
        Direction,
        Action,
        Type,
        ThresholdType,
        Threshold,
        Severity,
        Tactic,
        Name,
        Description
    | mv-expand Ports
    | mv-expand App
    | mv-expand Protocol
    | mv-expand Direction
    | mv-expand Action
    | extend
        Ports = tostring(Ports),
        App = tostring(App),
        Protocol = tostring(Protocol),
        Direction = tostring(Direction),
        Action = tostring(Action),
        Threshold = toint(Threshold);

Let binding: `NetworkSummary_Protocol`

let NetworkSummary_Protocol = materialize(
    union isfuzzy=true 
        (
        NetworkSummary_Protocol_CL
        | project v = int(2)
        ),
        (
        print int(1) 
        | project v = print_0
        )
    | summarize maxv = max(v)
    | extend
        NetworkSummary_Protocol_Exists = (maxv > 1),
        NetworkCustomAnalyticsExists = false
    );

Let binding: `NetworkCustomAnalytics`

let NetworkCustomAnalytics = materialize(
    union isfuzzy=true 
        (
        NetworkCustomAnalytics_protocol_CL
        | project v = int(2)
        ),
        (
        print int(1) 
        | project v = print_0
        )
    | summarize maxv = max(v)
    | extend
        NetworkCustomAnalyticsExists = (maxv > 1),
        NetworkSummary_Protocol_Exists = false
    );

union `isfuzzy=true` (3 sources)

Each leg below queries one source; the rule matches if any leg does. Sources: datatable(, datatable(exists:, NetworkSummary_Protocol_CL

Leg 1: `datatable(`

(datatable(
    exists: int,
    NetworkSummary_Protocol_Exists: bool,
    NetworkCustomAnalyticsExists: bool
)[
    1, false, false
]
        | join (NetworkSummary_Protocol) on NetworkSummary_Protocol_Exists
        | join (NetworkCustomAnalytics) on NetworkCustomAnalyticsExists
        )
        | join (
            _Im_NetworkSession(starttime=bin(now(-20m), 20m), endtime=bin(now(), 20m))
            | where TimeGenerated > bin(now(-20m), 20m)
            | summarize Count=count()
                by
                NetworkProtocol,
                DstPortNumber,
                DstAppName,
                NetworkDirection,
                DvcAction,
                bin(TimeGenerated, 20m)
            | extend
                EventTime = TimeGenerated,
                Count = toint(Count),
                DstPortNumber = toint(DstPortNumber),
                exists=int(1)
            )
            on exists
        | project-away exists*, maxv, NetworkSummary_Protocol_Exists*, NetworkCustomAnalyticsExists*

Leg 2: `datatable(exists:`

(datatable(exists: int, NetworkSummary_Protocol_Exists: bool)[1, false]
        | join (NetworkSummary_Protocol) on NetworkSummary_Protocol_Exists
        )
        | join (
            NetworkCustomAnalytics_protocol_CL
            | where EventTime_t == toscalar(NetworkCustomAnalytics_protocol_CL
                | summarize max(EventTime_t))
            | project
                NetworkProtocol=NetworkProtocol_s,
                DstPortNumber=DstPortNumber_d,
                DstAppName=DstAppName_s,
                NetworkDirection=NetworkDirection_s,
                DvcAction=DvcAction_s,
                Count=count__d,
                EventTime=EventTime_t,
                TimeGenerated,
                Type
            | extend Count = toint(Count), DstPortNumber = toint(DstPortNumber), exists=int(1)
            )
            on exists
        | project-away exists*, maxv, NetworkSummary_Protocol_Exists*, NetworkCustomAnalyticsExists*

Leg 3: `NetworkSummary_Protocol_CL`

NetworkSummary_Protocol_CL
        | where EventTime == toscalar(NetworkSummary_Protocol_CL
            | summarize max(EventTime))
        | project
            NetworkProtocol,
            DstPortNumber,
            DstAppName,
            NetworkDirection,
            DvcAction,
            Count=count_,
            EventTime,
            TimeGenerated,
            Type
        | extend Count = toint(Count), DstPortNumber = toint(DstPortNumber)

Applied to the combined result

| project-away exists*, maxv*, NetworkSummary_Protocol_Exists*, NetworkCustomAnalyticsExists* | where isnotempty(DstPortNumber) | summarize Sum=sum(Count) by DstPortNumber, NetworkProtocol, NetworkDirection, DvcAction | join kind=inner ['mapping'] where Ports has tostring(DstPortNumber) | where Sum > Threshold         
    and (Protocol == "*" or Protocol has NetworkProtocol)
    and (Direction == "*" or Direction has NetworkDirection)
    and (Action == "*" or Action has DvcAction) | project
    Name,
    Description,
    NetworkProtocol,
    DstPortNumber,
    NetworkDirection,
    DvcAction,
    Severity,
    Tactic | summarize
    NetworkProtocols=make_set_if(NetworkProtocol, isnotempty(NetworkProtocol), 20), 
    NetworkDirections=make_set_if(NetworkDirection, isnotempty(NetworkDirection), 5), 
    DvcActions=make_set_if(DvcAction, isnotempty(DvcAction), 10)
    by Name, Severity, Tactic, DstPortNumber, Description

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`Action`	cross_field_compare	`DvcAction` transforms: `op:match` corpus 2 (kusto 2)	`field:"Action" kind:cross_field_compare value:"DvcAction"`
`Action`	eq	`*` corpus 3 (kusto 3)	`field:"Action" kind:eq value:"*"`
`Direction`	cross_field_compare	`NetworkDirection` transforms: `op:match` corpus 2 (kusto 2)	`field:"Direction" kind:cross_field_compare value:"NetworkDirection"`
`Direction`	eq	`*` corpus 2 (kusto 2)	`field:"Direction" kind:eq value:"*"`
`DstPortNumber`	is_not_null	(no value, null check)	`field:"DstPortNumber" kind:is_not_null`
`Protocol`	cross_field_compare	`NetworkProtocol` transforms: `op:match` corpus 2 (kusto 2)	`field:"Protocol" kind:cross_field_compare value:"NetworkProtocol"`
`Protocol`	eq	`*` corpus 2 (kusto 2)	`field:"Protocol" kind:eq value:"*"`
`Severity`	ne	`Disabled` corpus 2 (kusto 2)	`field:"Severity" kind:ne value:"Disabled"`
`Sum`	cross_field_compare	`Threshold` transforms: `op:gt`	`field:"Sum" kind:cross_field_compare value:"Threshold"`
`ThresholdType`	eq	`Static`	`field:"ThresholdType" kind:eq value:"Static"`
`Type`	eq	`Detection` corpus 2 (kusto 2)	`field:"Type" kind:eq value:"Detection"`

Output fields

These fields are emitted when the rule matches.

Field	Source
`Description`	`summarize`
`DstPortNumber`	`summarize`
`DvcActions`	`summarize`
`Name`	`summarize`
`NetworkDirections`	`summarize`
`NetworkProtocols`	`summarize`
`Severity`	`summarize`
`Tactic`	`summarize`

Detect port misuse by static threshold (ASIM Network Session schema)

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Parameters

Let binding: mapping

Let binding: NetworkSummary_Protocol

Let binding: NetworkCustomAnalytics

union isfuzzy=true (3 sources)

Leg 1: datatable(

Leg 2: datatable(exists:

Leg 3: NetworkSummary_Protocol_CL