Thousands of WordPress websites are being hacked every day. It’s more than 60 thousand, and day by day the number is increasing. Once a website is hacked, there is a high chance that hackers left some special access code in applications to regain access in the future. Often we heard from our new clients that they cleaned the website themself but it’s being hacked repeatedly. In our investigations, we found various backdoor scripts and techniques that we will discuss today.

Why do WordPress websites get hacked?

All of these are some of the major reasons for being a WordPress Website hacked.
  • 1. Vulnerable WordPress installation
  • 2. Outdated WP Core, themes & plugins
  • 3. Insecure hosting platform
  • 4. Weak password
  • 5. Poorly coded design
Let’s focus on Backdoors that may be left if non-security professionals recover the website.

WordPress Administrator creator script

If you suspect your previous developer for the incident, the best place to find the source of this hack is your theme & plugin. This simple script below can create a WordPress administrator account with username as support and password: PassWord just visiting your website like this way.example.com/?autoupdate=go This script can hide administrator account support from the user list and decrease total user count by 1!

Webshell Backdoors

Web shell backdoors can be placed anywhere on your website. Most WordPress security plugins can detect only well-known web shells. Here is some location to hide web shells on WordPress website.

WordPress Themes

The majority of hidden web-shells backdoors we found into inactive themes. Because hacker knows that site owner won’t update the theme they don’t use! And simple thinking by the site owner, inactive theme doesn’t have anything to do with the website so leave it!. That’s a great mistake. We recommend, never keep an unused theme installed on your website, update or outdated doesn’t matter.

WP Plugins

Hackers choose plugins to hide backdoor because site owners sometimes afraid to update plugins as that may break the website. Premium plugins are the main target while pirated plugins are heaven because pirated plugins (premium plugins without a license) can’t be updated!

Upload Directory

Uploads directory is the directory where all user uploaded files such as image, document contents usually stored. It’s a safe place to hide web shell because here don’t have the risk of being deleted by WordPress, theme, or plugin update!

WP-config.php

The wp-config.php file is a popular target. Because this file contains Database name, usernames, password, hostname, and the first file being called by WordPress.

wp-includes directory

the wp-includes directory is another place to hide web-shell backdoor because only senior developers and security experts have the courage to touch this directory.

cPanel and SFTP/FTP Backdoor

Not only your WordPress website is hackable, your web hosting control panel is a good place to hide the root of the hack as well.

cPanel hidden contact and password reset email

Check these 2 files under your cPanel home directory if contain any unknown email: .contactmail.contactinfo cpanel-backdoor Those 2 files should contain your own email address. This email adderess is used to send password reset email and cPanel notification.Also check .lastlogin file and see if you can recognize the IP address that is listed there. This is the list of IP addresses being used to access the cPanel.Don’t forget to reset the cPanel password immediately.

FTP

These days FTP is not a secure protocol anymore. When doing website security hardening and trying to solving mysterious hack that is coming back again and again, make sure you didn’t have old used FTP accounts. We recommend removing all FTP account completely and if possible, use SFTP with a strong password or use Public Key authentication.

SSH key/SFTP user

Check for authorized SSH keys and SFTP user accounts in your control panel as well. Good place to hide legit backdoor!