{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Suspicious Certutil Command\n",
    "Detects a suspicious Microsoft certutil execution with sub commands like 'decode' sub command, which is sometimes used to decode malicious code with the built-in certutil utility"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Rule Content\n",
    "```\n",
    "- title: Suspicious Certutil Command\n",
    "  id: e011a729-98a6-4139-b5c4-bf6f6dd8239a\n",
    "  status: experimental\n",
    "  description: Detects a suspicious Microsoft certutil execution with sub commands\n",
    "    like 'decode' sub command, which is sometimes used to decode malicious code with\n",
    "    the built-in certutil utility\n",
    "  author: Florian Roth, juju4, keepwatch\n",
    "  modified: 2019/01/22\n",
    "  references:\n",
    "  - https://twitter.com/JohnLaTwC/status/835149808817991680\n",
    "  - https://twitter.com/subTee/status/888102593838362624\n",
    "  - https://twitter.com/subTee/status/888071631528235010\n",
    "  - https://blogs.technet.microsoft.com/pki/2006/11/30/basic-crl-checking-with-certutil/\n",
    "  - https://www.trustedsec.com/2017/07/new-tool-release-nps_payload/\n",
    "  - https://twitter.com/egre55/status/1087685529016193025\n",
    "  - https://lolbas-project.github.io/lolbas/Binaries/Certutil/\n",
    "  logsource:\n",
    "    category: process_creation\n",
    "    product: windows\n",
    "    service: null\n",
    "  detection:\n",
    "    selection:\n",
    "      CommandLine:\n",
    "      - '* -decode *'\n",
    "      - '* /decode *'\n",
    "      - '* -decodehex *'\n",
    "      - '* /decodehex *'\n",
    "      - '* -urlcache *'\n",
    "      - '* /urlcache *'\n",
    "      - '* -verifyctl *'\n",
    "      - '* /verifyctl *'\n",
    "      - '* -encode *'\n",
    "      - '* /encode *'\n",
    "      - '*certutil* -URL*'\n",
    "      - '*certutil* /URL*'\n",
    "      - '*certutil* -ping*'\n",
    "      - '*certutil* /ping*'\n",
    "    condition: selection\n",
    "  fields:\n",
    "  - CommandLine\n",
    "  - ParentCommandLine\n",
    "  tags:\n",
    "  - attack.defense_evasion\n",
    "  - attack.t1140\n",
    "  - attack.t1105\n",
    "  - attack.s0189\n",
    "  - attack.g0007\n",
    "  falsepositives:\n",
    "  - False positives depend on scripts and administrative tools used in the monitored\n",
    "    environment\n",
    "  level: high\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-*', 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='process_command_line.keyword:(*\\ \\-decode\\ * OR *\\ \\/decode\\ * OR *\\ \\-decodehex\\ * OR *\\ \\/decodehex\\ * OR *\\ \\-urlcache\\ * OR *\\ \\/urlcache\\ * OR *\\ \\-verifyctl\\ * OR *\\ \\/verifyctl\\ * OR *\\ \\-encode\\ * OR *\\ \\/encode\\ * OR *certutil*\\ \\-URL* OR *certutil*\\ \\/URL* OR *certutil*\\ \\-ping* OR *certutil*\\ \\/ping*)')\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
}