SAP BTP - Unaudited custom app with login-only activity

Requête originale, sans modification.

// Lookback period for audit events - a longer window avoids false positives for
// properly instrumented apps where users logged in but haven't performed actions yet
let audit_lookback = ago(7d);
// Known BTP platform service patterns (excluded from detection)
let platform_service_patterns = dynamic([
    "app-studio", "auditlog", "cis-local", "service-manager",
    "destination-xsappname", "connectivity-proxy", "feature-flags"
]);
// Step 1: From XSUAA TokenIssuedEvent, identify custom apps with interactive user logins
// XSUAA is a shared subaccount service - the client_id in each token identifies the actual app
let app_logins = SAPBTPAuditLog_CL
    // Scope logins to the current 1h run cycle (matches queryFrequency)
    | where TimeGenerated > ago(1h)
    | where Category == "audit.security-events"
    | extend data_s = tostring(Message.data)
    | where data_s has "TokenIssuedEvent"
    | extend ParsedData = parse_json(data_s)
    // origin field = client_id of the app the token was issued for
    | extend ClientId = tostring(ParsedData.origin)
    | where ClientId startswith "sb-"
    // Parse nested event message for human user and grant type
    | extend EventMessage = tostring(ParsedData.message)
    | extend GrantType = extract(@'"grant_type"\s*:\s*"([^"]+)"', 1, EventMessage)
    // Only interactive browser-based logins (not service-to-service tokens)
    | where GrantType == "authorization_code"
    // Derive app identifiers: sb-<XsAppName>!t<number>
    | extend XsAppName = extract(@"^sb-(.+?)!\w+$", 1, ClientId)
    | where isnotempty(XsAppName)
    // Exclude known platform services
    | where not(XsAppName has_any (platform_service_patterns))
    // Extract human-readable app name (first segment before subaccount qualifier)
    | extend AppName = extract(@"^([A-Za-z][A-Za-z0-9_]*)", 1, XsAppName)
    | extend HumanUser = extract(@'"user_name"\s*:\s*"([^"]+)"', 1, EventMessage)
    | extend IPAddress = tostring(Message.ip);
// Step 2a: Identify apps that have business audit events where the service binding
// identity appears in UserName (e.g. platform-generated audit events)
let audited_apps = SAPBTPAuditLog_CL
    | where TimeGenerated > audit_lookback
    | where Category !in ("audit.security-events")
    | where UserName startswith "sb-"
    | extend AuditedAppName = extract(@"^sb-(.+?)!\w+", 1, UserName)
    | where isnotempty(AuditedAppName)
    | distinct AuditedAppName, Tenant;
// Step 2b: Identify CF app instances that have an audit log service binding.
// When a CAP/custom app binds the audit log service, BTP provisions a
// 'customer-auditlog' service key whose XSUAA token events share the same
// AlsServiceId (CF app GUID) as the app's own login tokens. This gives a
// reliable per-app correlation that works even when the audit log service
// instance is deployed in a different CF space than the app itself.
let audited_app_instances = SAPBTPAuditLog_CL
    | where TimeGenerated > audit_lookback
    | where Category == "audit.security-events"
    | where UserName contains "customer-auditlog"
    | where isnotempty(AlsServiceId)
    | distinct AlsServiceId, Tenant;
// Step 3: Find custom apps with logins but no business audit trail
app_logins
| join kind=leftanti (audited_apps | project XsAppName = AuditedAppName, Tenant) on XsAppName, Tenant
| join kind=leftanti (audited_app_instances) on AlsServiceId, Tenant
| summarize
    LoginCount = count(),
    FirstLogin = min(TimeGenerated),
    LastLogin = max(TimeGenerated),
    Users = make_set(HumanUser, 100),
    IPs = make_set(IPAddress, 100),
    AppName = take_any(AppName),
    SubaccountName = take_any(SubaccountName),
    OrgId = take_any(OrgId),
    SpaceId = take_any(SpaceId)
    by XsAppName, ClientId, Tenant
| extend Users = set_difference(Users, dynamic([""]))
| project
    FirstLogin,
    LastLogin,
    AppName,
    XsAppName,
    ClientId,
    SubaccountName,
    Tenant,
    OrgId,
    SpaceId,
    LoginCount,
    Users,
    IPs,
    CloudApp = "SAP BTP"