[Entra ID] Suspicious Continuous OAuth Token Usage

Requête originale, sans modification.

// =====================
// Low-noise Token Reuse Detector (fixed timespan calc)
// =====================
let GapDays = 1;
let MinIPChanges = 2;
let MinLocChanges = 2;
let ExcludeApps = dynamic([
    "Microsoft Authentication Broker",
    "Microsoft Teams",
    "Office 365"
    ]);
let Src =
    union isfuzzy=true
        AADNonInteractiveUserSignInLogs,
        SigninLogs
    | where ResultType == 0
    | where isnotempty(UniqueTokenIdentifier);
let Past =
    Src
    | where TimeGenerated between (ago(14d) .. ago(1d))
    | summarize
        PastLastSeen = max(TimeGenerated),
        PastUPNs     = make_set(UserPrincipalName, 20),
        PastIPs      = make_set(IPAddress, 50),
        PastLocs     = make_set(tostring(Location), 50),
        PastApps     = make_set(AppDisplayName, 50)
        by UniqueTokenIdentifier;
let Last24h =
    Src
    | where TimeGenerated >= ago(1d)
    //| where AppDisplayName !in (ExcludeApps)
    | summarize
        CurrentFirstSeen = min(TimeGenerated),
        CurrentLastSeen  = max(TimeGenerated),
        CurrentUPNs      = make_set(UserPrincipalName, 20),
        CurrentIPs       = make_set(IPAddress, 50),
        CurrentLocs      = make_set(tostring(Location), 50),
        CurrentApps      = make_set(AppDisplayName, 50),
        IPCount          = dcount(IPAddress),
        LocCount         = dcount(tostring(Location))
        by UniqueTokenIdentifier, ResultType;
Last24h
| join kind=inner Past on UniqueTokenIdentifier
| extend Gap = CurrentFirstSeen - PastLastSeen
| extend GapThreshold = totimespan(strcat(GapDays, "d"))
| where Gap >= GapThreshold
| where IPCount >= MinIPChanges or LocCount >= MinLocChanges
| extend NewIPs  = set_difference(CurrentIPs, PastIPs)
| extend NewLocs = set_difference(CurrentLocs, PastLocs)
| where array_length(NewIPs) > 0 or array_length(NewLocs) > 0
| extend
    CurrentUPNCount = array_length(CurrentUPNs),
    PastUPNCount = array_length(PastUPNs)
| project
    UniqueTokenIdentifier,
    PastLastSeen,
    CurrentFirstSeen,
    CurrentLastSeen,
    Gap,
    GapThreshold,
    CurrentUPNs,
    CurrentUPNCount,
    CurrentIPs,
    IPCount,
    NewIPs,
    CurrentLocs,
    LocCount,
    NewLocs,
    CurrentApps,
    PastApps,
    PastUPNs,
    ResultType
| order by Gap desc, CurrentLastSeen desc
| extend UserNames = strcat_array(CurrentUPNs, ",")
| extend NewIP = strcat_array(NewIPs, ",")
| extend FirstNewIP = tostring(NewIPs[0])
| extend NewLoc = strcat_array(NewLocs, ",")
| extend PastUPN = strcat_array(PastUPNs, ",")
| extend Source_Network_IPLocation = ""
| project
    Alert_Time_TW = datetime_utc_to_local(CurrentLastSeen, 'Asia/Taipei'),
    Alert_Time_UTC0 = CurrentLastSeen,
        Alert_Category_en = "Entra ID",
    Alert_SubCategory_en = "Anomaly Network Access User",
    Alert_Name_en = "Abnormal Sign-in Token Reuse",
    Alert_Description_en=strcat(
                         "At Taiwan time: ",
                         format_datetime(datetime_utc_to_local(CurrentLastSeen, "Asia/Taipei"), "yyyy-MM-dd HH:mm:ss"),
                         ", detected suspected Token Reuse behavior (UniqueTokenIdentifier appeared repeatedly and the interval reached the threshold).",
                         "Token:",
                         iff(isnotempty(UniqueTokenIdentifier), UniqueTokenIdentifier, "<NoTokenId>"),
                         ", users (last 2 days): ",
                         iff(isnotempty(tostring(UserNames)), tostring(UserNames), "<NoUserNames>"),
                         ", previous last seen: ",
                         format_datetime(datetime_utc_to_local(PastLastSeen, "Asia/Taipei"), "yyyy-MM-dd HH:mm:ss"),
                         ", current first seen: ",
                         format_datetime(datetime_utc_to_local(CurrentFirstSeen, "Asia/Taipei"), "yyyy-MM-dd HH:mm:ss"),
                         ", gap: ",
                         tostring(Gap),
                         " days",
                         ", IP count: ",
                         tostring(IPCount),
                         ", current sign-in IP: ",
                         iff(isnotempty(tostring(NewIP)), tostring(NewIP), "<NoNewIP>"),
                         ", location count: ",
                         tostring(LocCount),
                         ", current sign-in location: ",
                         iff(isnotempty(tostring(NewLoc)), tostring(NewLoc), "<NoNewLoc>"),
                         "."
                     ),
    Alert_TriageStep_en=strcat(
                        " 1. Check whether this is truly token reuse. The reused IP is: ",
                        iff(isnotempty(tostring(NewIP)), tostring(NewIP), "<NoNewIPs>"),
                        ", current sign-in location: ",
                        iff(isnotempty(tostring(NewLoc)), tostring(NewLoc), "<NoNewLocs>"),
                        "  to determine whether it is an uncommon source, cross-country/cross-region, or anonymous cloud egress.",
                        " 2. Check whether multiple accounts share the same token. Current triggering account count: ",
                        tostring(CurrentUPNCount),
                        ", accounts that previously triggered this token: ",
                        tostring(PastUPN),
                        "; if the UPN count is greater than 1, prioritize suspicion of token leakage or proxy/automation abuse.",
                        " 3. Check the applications currently involved in sign-in: ",
                        iff(isnotempty(tostring(CurrentApps)), tostring(CurrentApps), "<NoCurrentApps>"),
                        "previous sign-in applications: ",
                        iff(isnotempty(tostring(PastApps)), tostring(PastApps), "<NoPastApps>"),
                        "  to determine whether they include administrative/highly sensitive applications or abnormally newly added apps."
                    ),
    Alert_Containment_en=strcat(
                         "1. Immediately revoke sign-in tokens/sessions and force re-sign-in for users (last 2 days): ",
                         iff(isnotempty(tostring(UserNames)), tostring(UserNames), "<NoUserNames>"),
                         "  to block continued access using the reused token.  ",
                         "2. If the current sign-in IP or location is abnormal, immediately block the current sign-in IP: ",
                         iff(isnotempty(tostring(NewIP)), tostring(NewIP), "<NoNewIP>"),
                         ", current sign-in location: ",
                         iff(isnotempty(tostring(NewLoc)), tostring(NewLoc), "<NoNewLoc>"),
                         ", and tighten Conditional Access (MFA/compliant device/named location).  ",
                         "3. Immediately require account security recovery: reset the password, re-register MFA, and check for suspicious devices or added authentication methods.  "
                     ),
    Alert_Remediation_en=strcat(
                         "1. Strengthen risk-based access: establish Conditional Access policies to block new IPs/new locations.  ",
                         "2. Implement token protection and endpoint governance: promote compliant devices, reduce long-lived token risk, and restrict access from unmanaged devices or legacy clients.  ",
                         "3. Inventory automation and applications: regularly check for abnormally added applications and high-privilege applications, and remove unnecessary permissions and old credentials.  ",
                         "4. Establish automated response: automatically revoke tokens, block IPs, notify users for confirmation, and create incident tickets for follow-up investigation when alerts trigger."
                     ),
            Event_Code = ResultType,
    //Event_Description = ResultDescription,
    Event_TimeRange_Start_UTC0 = CurrentFirstSeen,
    Event_TimeRange_End_UTC0 = CurrentLastSeen,
    Event_TimeRange_Start_TW = datetime_utc_to_local(CurrentFirstSeen, 'Asia/Taipei'),
    Event_TimeRange_End_TW = datetime_utc_to_local(CurrentFirstSeen, 'Asia/Taipei'),
    Source_Identity_FullName = UserNames,
    Source_Network_IPAddress = NewIP,
    Source_Network_IPLocation = Source_Network_IPLocation,
    Target_Identity_FullName = UniqueTokenIdentifier,
    //Target_Network_IPAddress = UniqueTokenIdentifier,
    //Target_Resource_ID = "",
    Target_Resource_Name = "Microsoft Entra ID",
    Target_Resource_Type = "Microsoft Entra ID"