[metadata]
creation_date = "2023/06/26"
integration = ["endpoint"]
maturity = "production"
min_stack_comments = "New fields added: required_fields, related_integrations, setup"
min_stack_version = "8.3.0"
updated_date = "2023/06/26"

[rule]
author = ["Elastic"]
description = """
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.
"""
from = "now-9m"
index = ["logs-endpoint.events.*"]
language = "eql"
license = "Elastic License v2"
name = "Suspicious Data Encryption via OpenSSL Utility"
references = [
  "https://www.welivesecurity.com/2017/06/30/telebots-back-supply-chain-attacks-against-ukraine/",
  "https://www.trendmicro.com/en_us/research/21/f/bash-ransomware-darkradiation-targets-red-hat--and-debian-based-linux-distributions.html",
]
risk_score = 47
rule_id = "f530ca17-153b-4a7a-8cd3-98dd4b4ddf73"
severity = "medium"
tags = ["Domain: Endpoint", "OS: Linux", "Use Case: Threat Detection", "Tactic: Impact"]
type = "eql"
query = '''
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") ] with runs=10
'''

[[rule.threat]]
framework = "MITRE ATT&CK"

[rule.threat.tactic]
name = "Impact"
id = "TA0040"
reference = "https://attack.mitre.org/tactics/TA0040/"

[[rule.threat.technique]]
name = "Data Encrypted for Impact"
id = "T1486"
reference = "https://attack.mitre.org/techniques/T1486/"