Anomalous login followed by Teams action

Requête originale, sans modification.

//The bigger the window the better the data sample size, as we use IP prevalence, more sample data is better.
//The minimum number of countries that the account has been accessed from [default: 2]
let minimumCountries = 2;
//The delta (%) between the largest in-use IP and the smallest [default: 95]
let deltaThreshold = 95;
//The maximum (%) threshold that the country appears in login data [default: 10]
let countryPrevalenceThreshold = 10;
//The time to project forward after the last login activity [default: 60min]
let projectedEndTime = 60m;
let queryfrequency = 1d;
let queryperiod = 14d;
let aadFunc = (tableName: string) {
    // Get successful signins to Teams
    let signinData =
        table(tableName)
        | where TimeGenerated > ago(queryperiod)
        | where AppDisplayName has "Teams" and ConditionalAccessStatus =~ "success"
        | extend Country = tostring(todynamic(LocationDetails)['countryOrRegion'])
        | where isnotempty(Country) and isnotempty(IPAddress);
    // Calculate prevalence of countries
    let countryPrevalence =
        signinData
        | summarize CountCountrySignin = count() by Country
        | extend TotalSignin = toscalar(signinData | summarize count())
        | extend CountryPrevalence = toreal(CountCountrySignin) / toreal(TotalSignin) * 100;
    // Count signins by user and IP address
    let userIpSignin =
        signinData
        | summarize CountIPSignin = count(), Country = any(Country), ListSigninTimeGenerated = make_list(TimeGenerated) by IPAddress, UserPrincipalName;
    // Calculate delta between the IP addresses with the most and minimum activity by user
    let userIpDelta =
        userIpSignin
        | summarize MaxIPSignin = max(CountIPSignin), MinIPSignin = min(CountIPSignin), DistinctCountries = dcount(Country), make_set(Country) by UserPrincipalName
        | extend UserIPDelta = toreal(MaxIPSignin - MinIPSignin) / toreal(MaxIPSignin) * 100;
    // Collect Team operations the user account has performed within a time range of the suspicious signins
    OfficeActivity
    | where TimeGenerated > ago(queryfrequency)
    | where Operation in~ ("TeamsAdminAction", "MemberAdded", "MemberRemoved", "MemberRoleChanged", "AppInstalled", "BotAddedToTeam")
    | where not (Operation in~ ("MemberAdded", "MemberRemoved") and CommunicationType in~ ("GroupChat", "OneonOne")) // These events have been noisy and are related to initiaing chat conversation and not admin operations.
    | project OperationTimeGenerated = TimeGenerated, UserId = tolower(UserId), Operation
    | join kind = inner(
        userIpDelta
        // Check users with activity from distinct countries
        | where DistinctCountries >= minimumCountries
        // Check users with high IP delta
        | where UserIPDelta >= deltaThreshold
        // Add information about signins and countries
        | join kind = leftouter userIpSignin on UserPrincipalName
        | join kind = leftouter countryPrevalence on Country
        // Check activity that comes from nonprevalent countries
        | where CountryPrevalence < countryPrevalenceThreshold
        | project
            UserPrincipalName,
            SuspiciousIP = IPAddress,
            UserIPDelta,
            SuspiciousSigninCountry = Country,
            SuspiciousCountryPrevalence = CountryPrevalence,
            EventTimes = ListSigninTimeGenerated
    ) on $left.UserId == $right.UserPrincipalName
    // Check the signins occured 60 min before the Teams operations
    | mv-expand SigninTimeGenerated = EventTimes
    | extend SigninTimeGenerated = todatetime(SigninTimeGenerated)
    | where OperationTimeGenerated between (SigninTimeGenerated .. (SigninTimeGenerated + projectedEndTime))
};
let aadSignin = aadFunc("SigninLogs");
let aadNonInt = aadFunc("AADNonInteractiveUserSignInLogs");
union isfuzzy=true aadSignin, aadNonInt
| summarize arg_max(SigninTimeGenerated, *) by UserPrincipalName, SuspiciousIP, OperationTimeGenerated
| summarize
    ActivitySummary = make_bag(pack(tostring(SigninTimeGenerated), pack("Operation", tostring(Operation), "OperationTime", OperationTimeGenerated)))
    by UserPrincipalName, SuspiciousIP, SuspiciousSigninCountry, SuspiciousCountryPrevalence
| extend AccountName = tostring(split(UserPrincipalName, "@")[0]), AccountUPNSuffix = tostring(split(UserPrincipalName, "@")[1])