sap multi terminal logon

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 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
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 *
 *     https://www.apache.org/licenses/LICENSE-2.0
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rule sap_multi_terminal_logon {

  meta:
    author = "Google Cloud Security"
    description = "Identifies successful logons for the same User ID from multiple different terminal IDs or client hostnames in a short timeframe, indicating potential credential sharing or session theft."
    severity = "medium"
    tactic = "TA0006"
    technique = "T1078"

  events:
    $e.metadata.log_type = "SAP_SECURITY_AUDIT"
    (
        $e.metadata.event_type = "USER_LOGIN" or
        $e.additional.fields["msg_1"] = /^AU1$|^AU5$/
    )


    // Ensure we only check events that actually have a terminal/hostname recorded
    $e.principal.hostname != ""

    $terminal = $e.principal.hostname
    $user = $e.principal.user.userid

  match:
    // You can reduce this window to 15m or 30m if 1h is too broad for direct terminal switches
    $user over 15m

  outcome:
    $terminals = array_distinct($terminal)
    $count_of_terminals = count_distinct($terminal)
    // Give a high risk score if they switch terminals
    $risk_score = 60
    $sap_instance = array_distinct($e.target.resource.name)

  condition:
    // Trigger if the user is seen on 2 or more distinct terminals
    #terminal >= 2
}