Esse post tô fazendo pois eu sempre preciso disso na hora de atualizar meu site e acabo esquecendo.
Então vou deixar aqui um scriptzinho que eu encontrei que facilita na hora de definir permissoes no worpress.
#!/bin/bash
#
# This script configures WordPress file permissions based on recommendations
# from http://codex.wordpress.org/Hardening_WordPress#File_permissions
#
# Author: Michael Conigliaro
#
WP_OWNER=changeme # <-- wordpress owner
WP_GROUP=changeme # <-- wordpress group
WP_ROOT=/home/changeme # <-- wordpress root directory
WS_GROUP=changeme # <-- webserver group
# reset to safe defaults
find ${WP_ROOT} -exec chown ${WP_OWNER}:${WP_GROUP} {} \;
find ${WP_ROOT} -type d -exec chmod 755 {} \;
find ${WP_ROOT} -type f -exec chmod 644 {} \;
# allow wordpress to manage wp-config.php (but prevent world access)
chgrp ${WS_GROUP} ${WP_ROOT}/wp-config.php
chmod 660 ${WP_ROOT}/wp-config.php
# allow wordpress to manage .htaccess
touch ${WP_ROOT}/.htaccess
chgrp ${WS_GROUP} ${WP_ROOT}/.htaccess
chmod 664 ${WP_ROOT}/.htaccess
# allow wordpress to manage wp-content
find ${WP_ROOT}/wp-content -exec chgrp ${WS_GROUP} {} \;
find ${WP_ROOT}/wp-content -type d -exec chmod 775 {} \;
find ${WP_ROOT}/wp-content -type f -exec chmod 664 {} \;
https://gist.github.com/macbleser/9136424
Outros links sobre segurança no wordpress
https://wordpress.stackexchange.com/questions/391949/wordpress-sites-being-filled-with-random-php-files
https://www.digitalocean.com/community/questions/how-to-secure-wordpress-without-a-security-plugin
