Generates a few fake files to exercise various malware scanning engines

gendata.sh

#!/usr/bin/env bash

set -eo pipefail

PARAMS=""
while (( "$#" )); do
  case "$1" in
    -d|--dest)
      if [ -n "$2" ] && [ ${2:0:1} != "-" ]; then
        DESTDIR=$2
        shift 2
      else
        echo "Error: Argument for $1 is missing" >&2
        exit 1
      fi
      ;;
    -t|--type)
      if [ -n "$2" ] && [ ${2:0:1} != "-" ]; then
        FILETYPE=$2
        shift 2
      else
        echo "Error: Argument for $1 is missing" >&2
        exit 1
      fi
      ;;
    -c|--count)
      if [ -n "$2" ] && [ ${2:0:1} != "-" ]; then
        FILECOUNT=$2
        shift 2
      else
        echo "Error: Argument for $1 is missing" >&2
        exit 1
      fi
      ;;
    -s|--size)
      if [ -n "$2" ] && [ ${2:0:1} != "-" ]; then
        FILESIZE=$2
        shift 2
      else
        echo "Error: Argument for $1 is missing" >&2
        exit 1
      fi
      ;;
    -*|--*=) # unsupported flags
      echo "Error: Unsupported flag $1" >&2
      exit 1
      ;;
    *) # preserve positional arguments
      PARAMS="$PARAMS $1"
      shift
      ;;
  esac
done
# set positional arguments in their proper place
eval set -- "$PARAMS"

if [ ! -d "${DESTDIR}" ]; then
	echo "Error: Invalid destination directory. ${DESTDIR} does not exist."
	exit 1
fi

# Default to one file, one KB, of type ELF
FILECOUNT="${FILECOUNT:-1}"
FILESIZE="${FILESIZE:-1024}"
FILETYPE="${FILETYPE:-elf}"

function generate_basename {
  chars=abcdefghijklmnopqrstuvwxyz1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ
  for i in {1..20} ; do
      echo -n "${chars:RANDOM%${#chars}:1}"
  done
}

function generate_elf {
	DESTDIR="${1}"
	FILESIZE="${2}"
	BASENAME="$(generate_basename)"
	FILE="${DESTDIR}/${BASENAME}.elf"
	echo -n -e \\x7F\\x45\\x4C\\x46\\x02\\x01\\x01\\x03\\x00\\x00\\x00\\x00\\x00\\x00\\x00\\x00\\x02\\x00\\x3E\\x00\\x00\\x00\\x00\\x01 > "${FILE}"
	openssl rand "${FILESIZE}" >> "${FILE}"
}
function generate_exe {
	DESTDIR="${1}"
	FILESIZE="${2}"
	BASENAME="$(generate_basename)"
	FILE="${DESTDIR}/${BASENAME}.exe"
	echo -n -e \\x4D\\x5A\\00\\00 > "${FILE}"
	openssl rand "${FILESIZE}" >> "${FILE}"
}
function generate_pdf {
	DESTDIR="${1}"
	FILESIZE="${2}"
	BASENAME="$(generate_basename)"
	FILE="${DESTDIR}/${BASENAME}.pdf"
	echo -n -e \\x25\\x50\\x44\\x46\\x2D > "${FILE}"
	openssl rand "${FILESIZE}" >> "${FILE}"
}
function generate_zip {
	DESTDIR="${1}"
	FILESIZE="${2}"
	BASENAME="$(generate_basename)"
	FILE="${DESTDIR}/${BASENAME}.zip"
	echo -n -e \\x50\\x4B\\x03\\x04 > "${FILE}"
	openssl rand "${FILESIZE}" >> "${FILE}"
}
function generate_png {
	DESTDIR="${1}"
	FILESIZE="${2}"
	BASENAME="$(generate_basename)"
	FILE="${DESTDIR}/${BASENAME}.png"
	echo -n -e \\x89\\x50\\x4E\\x47\\x0D\\x0A\\x1A\\x0A > "${FILE}"
	openssl rand "${FILESIZE}" >> "${FILE}"
}

function generate_file {
	DESTDIR="${1}"
	FILETYPE="${2}"
	FILESIZE="${3}"
	case "${FILETYPE}" in
		elf|ELF)
      generate_elf "${DESTDIR}" "${FILESIZE}"
      ;;
		exe|EXE)
      generate_exe "${DESTDIR}" "${FILESIZE}"
      ;;
		pdf|PDF)
      generate_pdf "${DESTDIR}" "${FILESIZE}"
			;;
		zip|ZIP)
      generate_zip "${DESTDIR}" "${FILESIZE}"
      ;;
		png|PNG)
      generate_png "${DESTDIR}" "${FILESIZE}"
      ;;
    *)
      echo "Error: Invalid filetype passed."
			exit 1
      ;;
  esac
}

echo -n "Writing to ${DESTDIR} ${FILECOUNT} ${FILETYPE} files of ${FILESIZE} bytes..."
for (( c=1; c<=$FILECOUNT; c++ )); do
  generate_file "${DESTDIR}" "${FILETYPE}" "${FILESIZE}"
done
echo "done."