{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# PowerShell Downgrade Attack\n",
    "Detects PowerShell downgrade attack by comparing the host versions with the actually used engine version 2.0"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Rule Content\n",
    "```\n",
    "- title: PowerShell Downgrade Attack\n",
    "  id: 6331d09b-4785-4c13-980f-f96661356249\n",
    "  status: experimental\n",
    "  description: Detects PowerShell downgrade attack by comparing the host versions\n",
    "    with the actually used engine version 2.0\n",
    "  references:\n",
    "  - http://www.leeholmes.com/blog/2017/03/17/detecting-and-preventing-powershell-downgrade-attacks/\n",
    "  tags:\n",
    "  - attack.defense_evasion\n",
    "  - attack.execution\n",
    "  - attack.t1086\n",
    "  author: Florian Roth (rule), Lee Holmes (idea)\n",
    "  logsource:\n",
    "    product: windows\n",
    "    service: powershell-classic\n",
    "    category: null\n",
    "  detection:\n",
    "    selection:\n",
    "      EventID: 400\n",
    "      EngineVersion: 2.*\n",
    "    filter:\n",
    "      HostVersion: 2.*\n",
    "    condition: selection and not filter\n",
    "  falsepositives:\n",
    "  - Penetration Test\n",
    "  - Unknown\n",
    "  level: medium\n",
    "\n",
    "```"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Querying Elasticsearch"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Import Libraries"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from elasticsearch import Elasticsearch\n",
    "from elasticsearch_dsl import Search\n",
    "import pandas as pd"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Initialize Elasticsearch client"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "es = Elasticsearch(['http://helk-elasticsearch:9200'])\n",
    "searchContext = Search(using=es, index='logs-endpoint-winevent-powershell-*', doc_type='doc')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Run Elasticsearch Query"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "s = searchContext.query('query_string', query='((event_id:\"400\" AND powershell.engine.version.keyword:2.*) AND (NOT (powershell.host.version.keyword:2.*)))')\n",
    "response = s.execute()\n",
    "if response.success():\n",
    "    df = pd.DataFrame((d.to_dict() for d in s.scan()))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Show Results"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "df.head()"
   ]
  }
 ],
 "metadata": {},
 "nbformat": 4,
 "nbformat_minor": 4
}