Elastic medium stable eql

Suspicious Data Encryption via OpenSSL Utility

Identifies when the openssl command-line utility is used to encrypt multiple files on a host within a short time window. Adversaries may encrypt data on a single or multiple systems in order to disrupt the availability of their target's data and may attempt to hold the organization's data to ransom for the purposes of extortion.

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Detection Logic

sequence by host.id, user.name, process.parent.entity_id with maxspan=5s
  [ process where host.os.type == "linux" and event.action == "exec" and
    process.name == "openssl" and process.parent.name : ("bash", "dash", "sh", "tcsh", "csh", "zsh", "ksh", "fish", "perl*", "php*", "python*", "xargs") and
    process.args == "-in" and process.args == "-out" and
    process.args in ("-k", "-K", "-kfile", "-pass", "-iv", "-md") and
    /* excluding base64 encoding options and including encryption password or key params */
    not process.args in ("-d", "-a", "-A", "-base64", "-none", "-nosalt") and
    not (process.parent.command_line == "bash -s" and process.args like "/root/recipes/recipes*")
  ] with runs=10

Field Validations

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