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Detect port misuse by anomaly based detection (ASIM Network Session schema)

Description

'This rule detects anomalous pattern in port usage. 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.'
Rule type
Scheduled
Version
1.3.0
Declared status
Available
Query frequency
1d
Query period
14d
Trigger
gt 0

Declared MITRE coverage

Declared sources

Metadata from the source file. No dependencies inferred from KQL.

Connectors

Data types

KQL query

Original query, unchanged.

let lookback = 14d;
let mapping = _GetWatchlist('NetworkSession_Monitor_Configuration')
    | where Type == "Detection" and ThresholdType == "Anomaly" 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 AnomalyThreshold = 2.5;
let eps = materialize (_Im_NetworkSession
    | project TimeGenerated
    | where TimeGenerated > ago(5m)
    | count
    | extend Count = Count / 300);
let maxSummarizedTime = toscalar (
    union isfuzzy=true
        (
        NetworkSummary_Protocol_CL
        | where EventTime > ago(lookback)
        | summarize max_TimeGenerated=max(EventTime)
        | extend max_TimeGenerated = datetime_add('minute', 20, max_TimeGenerated)
        ),
        (
        NetworkCustomAnalytics_protocol_CL
        | where EventTime_t > ago(lookback)
        | summarize max_TimeGenerated=max(EventTime_t)
        | extend max_TimeGenerated = datetime_add('minute', 20, max_TimeGenerated)
        ),
        (
        print(ago(lookback))
        | project max_TimeGenerated = print_0
        )
    | summarize maxTimeGenerated = max(max_TimeGenerated) 
    );
let NetworkSummary_Protocol = materialize(
    union isfuzzy=true 
        (
        NetworkSummary_Protocol_CL
        | where EventTime > ago(1d)
        | 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
        | where EventTime_t > ago(1d) 
        | 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
]
        | where toscalar(eps) > 500
        | join (NetworkSummary_Protocol) on NetworkSummary_Protocol_Exists
        | join (NetworkCustomAnalytics) on NetworkCustomAnalyticsExists
        )
        | join (
            _Im_NetworkSession(starttime=todatetime(ago(3d)), endtime=now())
            | where TimeGenerated > maxSummarizedTime
            | summarize Count=count()
                by
                NetworkProtocol,
                DstPortNumber,
                DstAppName,
                NetworkDirection,
                DvcAction,
                bin(TimeGenerated, 10m)
            | 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,
    NetworkCustomAnalyticsExists: bool
)[
    1, false, false
]
        | where toscalar(eps) <= 500
        | join (NetworkSummary_Protocol) on NetworkSummary_Protocol_Exists
        | join (NetworkCustomAnalytics) on NetworkCustomAnalyticsExists
        )
        | join (
            _Im_NetworkSession(starttime=todatetime(ago(4d)), endtime=now())
            | where TimeGenerated > maxSummarizedTime
            | summarize Count=count()
                by
                NetworkProtocol,
                DstPortNumber,
                DstAppName,
                NetworkDirection,
                DvcAction,
                bin(TimeGenerated, 10m)
            | 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 > ago(lookback)
            | 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 > ago(lookback)
        | 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)
| make-series Total=sum(Count) on EventTime from ago(lookback) to now() step 1d by DstPortNumber, NetworkProtocol, NetworkDirection, DvcAction
| extend (anomalies, score, baseline) = series_decompose_anomalies(Total, AnomalyThreshold, -1, 'linefit')
| mv-expand anomalies, score, baseline, EventTime, Total
| extend
    anomalies = toint(anomalies),
    score = toint(score),
    baseline = toint(baseline),
    EventTime = todatetime(EventTime),
    Total = tolong(Total)
| where EventTime >= ago(1d)
| extend DstPortNumber = tostring(DstPortNumber)
| where score >= 2 * AnomalyThreshold and baseline > 0
| join kind=inner ['mapping'] where Ports == DstPortNumber
| where (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

Related content

Links established from declared identifiers and solution manifests.

Source provenance

GitHub

Displayed values come from files in Azure/Azure-Sentinel. They describe the published template, not your workspace configuration.

Source identifier
cbf07406-fa2a-48b0-82b8-efad58db14ec
Additional source files 2Solutions/Network Session Essentials/Analytic Rules/DetectPortMisuseByAnomalyBasedDetection.yamlsource ↗Solutions/Network Session Essentials/Data/Solution_NetworkSessionEssentials.jsonsolution-membership ↗
GSTEP / CATALOG TRACKING

Added to catalog : 16 Sept 2026 · 05:49 UTC
Last change observed : 16 Sept 2026 · 05:49 UTC

GSTEP sync dates, separate from the source content’s publication dates.