[wp-trac] [WordPress Trac] #63697: CSRF Vulnerability in WordPress Plugin: A Responsible Disclosure Case Study

[WordPress Trac]

#63697: CSRF Vulnerability in WordPress Plugin: A Responsible Disclosure Case Study
----------------------------+-------------------------------------
 Reporter:  aimankg778      |      Owner:  (none)
     Type:  defect (bug)    |     Status:  new
 Priority:  normal          |  Milestone:  Awaiting Review
Component:  Editor          |    Version:  6.7
 Severity:  normal          |   Keywords:  has-patch has-test-info
  Focuses:  administration  |
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 Discovered a CSRF vulnerability in a WordPress plugin, reported it
 ethically, and helped improve security. Read the full case study.

 ## 🔍 Introduction

 As part of my routine code review of popular WordPress plugins, I
 discovered a CSRF (Cross-Site Request Forgery) vulnerability in a plugin
 called **Simple Social Buttons**. This vulnerability could potentially
 allow an attacker to trick a logged-in administrator into making unwanted
 changes without their consent.

 This post details my responsible disclosure journey, technical findings,
 and lessons learned.

 ---

 ## 🧠 What is CSRF?

 CSRF (Cross-Site Request Forgery) is a type of web attack where a logged-
 in user is tricked into submitting a request that they did not intend. In
 WordPress, this is usually prevented by using **nonces** — security tokens
 that validate requests.

 ---

 ## 🛠️ The Vulnerability

 While analyzing the plugin settings page, I noticed that:

 - The settings form used the POST method
 - No WordPress nonce (`wp_nonce_field()`) was included
 - No verification using `check_admin_referer()` was performed on form
 submission

 This means if an attacker could lure an admin to a malicious site, it
 could silently submit that form in the background and alter plugin
 settings.

 ---

 ## 🔐 Responsible Disclosure

 Once I confirmed the issue, I:

 1. Documented the steps to reproduce it (PoC)
 2. Contacted the plugin authors privately via email
 3. Gave them time to fix the issue before posting anything public

 ---

 ## ✅ The Fix

 The plugin authors responded professionally and pushed a patch in version
 `x.x.x`. They added:

 - Nonce field to the form: `wp_nonce_field( 'ssb_settings_save',
 'ssb_nonce' );`
 - Nonce check on save: `check_admin_referer( 'ssb_settings_save',
 'ssb_nonce' );`

 This is now the correct and secure way to handle such settings.

 ---

 ## 📚 Lessons for Developers

 - Always use **nonces** on any form that updates settings
 - Validate the nonce using `check_admin_referer()` or `wp_verify_nonce()`
 - Never assume a form is safe just because it's only visible to admins

 ---

 ## 📢 Final Thoughts

 Security is a shared responsibility. If you’re building WordPress plugins,
 don’t overlook nonce protection. If you find a vulnerability, report it
 ethically — you’ll help make the ecosystem stronger for everyone.


 Want more WordPress security insights? Visit my blog at
 [https://truyenqq.asia

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Ticket URL: <https://core.trac.wordpress.org/ticket/63697>
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