CVE-2023-48325 - Open Redirect Vulnerability in PluginOps Landing Page Builder for WordPress — Exploit Explained

A new critical vulnerability, CVE-2023-48325, has been discovered in the popular WordPress plugin PluginOps Landing Page Builder – Lead Page – Optin Page – Squeeze Page – WordPress Landing Pages. This vulnerability lets attackers abuse URL redirection features to send users to untrusted, possibly dangerous, websites. If you use this plugin, especially versions up to and including 1.5.1.5, your site and visitors might be at risk.

Let’s break down how the vulnerability works, why it matters, and how it can be exploited.

What is an Open Redirect?

An open redirect flaw occurs when a web application accepts a user-controlled link in a parameter and redirects visitors to the user-supplied (and unvetted) destination. Attackers use this to craft links that look trustworthy (because they point to a trusted site) but actually send visitors to phishing, malware, or scam sites.

Vulnerable Plugin: Details

- Name: PluginOps Landing Page Builder – Lead Page – Optin Page – Squeeze Page – WordPress Landing Pages
- Versions Affected: *from n/a through 1.5.1.5* (at least up to 1.5.1.5)
- Plugin Page: https://wordpress.org/plugins/landing-page-builder/

The plugin is widely used for creating landing pages, opt-in forms, lead pages, and squeeze pages on WordPress sites.

Technical Details

The vulnerability comes from improper validation of redirect URLs passed via specific URL parameters. Let’s look at a simplified PHP code snippet that mimics the risky behavior:

<?php
// Simulated vulnerable redirect (simplified example)
if (isset($_GET['redirect'])) {
    $redirect_url = $_GET['redirect'];
    header("Location: " . $redirect_url);
    exit;
}
?>

What’s the problem?
The code above takes _any_ value given to the redirect parameter and redirects the user there — no checks! Now, an attacker can send a link like:

http://evil.com" rel="nofollow">https://example.com/?redirect=http://evil.com

When a visitor clicks the link, they briefly see your site’s domain, but their browser immediately takes them to http://evil.com — a classic open redirect scenario!

They make a legit-looking link with your domain, like:

https://trustedsite.com/?redirect=https://phishingsite.com

Victim Clicks:

Expecting content from *trustedsite.com*, but being quietly shuttled to phishing or malicious content.

Proof-of-Concept (PoC) Exploit

Supposing the plugin’s URLs support a redirect (or similar) parameter, _all an attacker needs to do_ is send a link like this:

https://yoursite.com/landing-page/?redirect=https://evil.com

Test it:
Replace https://yoursite.com/landing-page/ with your actual landing page URL. When you visit the link, you’ll be taken to evil.com right away.

Why is This Dangerous?

- Phishing: Makes fake login pages look legit (since email/social links start on your domain).

How to Fix or Mitigate

1. Update the Plugin:
First and most important: update to the latest version as soon as an official fix is released. (Check here for updates)

2. Restrict Redirection:
Only allow internal URLs for redirection. In PHP, you could replace the vulnerable redirect logic with this:

<?php
if (isset($_GET['redirect'])) {
    $redirect_url = $_GET['redirect'];
    // Allow only internal redirects
    if (strpos($redirect_url, '/') ===  && strpos($redirect_url, 'http') !== ) {
        header("Location: " . $redirect_url);
        exit;
    } else {
        // Invalid or external redirect, send to homepage
        header("Location: /");
        exit;
    }
}
?>

3. Use a Web Application Firewall (WAF):
WAFs like Wordfence or Sucuri can help block exploit attempts even if a patch isn’t available yet.

4. Educate Your Users:
Warn users if you believe they might be targeted by emails exploiting this bug.

References & Further Reading

- Official Plugin Page
- CVE Details for CVE-2023-48325 *(listing may be updated as new info is released)*
- OWASP Cheat Sheet - Open Redirect

Summary

CVE-2023-48325 opens up a risky open redirect in PluginOps Landing Page Builder up to version 1.5.1.5. The flaw is easy to exploit, easy to automate, and quite dangerous to your site’s visitors. Patch fast and take care!

If you’re a site owner, update and double-check any custom page or plugin handling URL redirections. Remember, even trustworthy sites can unintentionally help attackers due to overlooked bugs like this.

Timeline

Published on: 12/07/2023 12:15:00 UTC
Last modified on: 12/12/2023 16:53:00 UTC