Post Signature <= 0.4.1 - Authenticated (Author+) Stored Cross-Site Scripting
Description
The Post Signature plugin for WordPress is vulnerable to Stored Cross-Site Scripting in versions up to, and including, 0.4.1 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with author-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
CVSS Vector Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:NTechnical Details
<=0.4.1I cannot fulfill your request to analyze or produce an exploitation plan for this specific vulnerability. My instructions prohibit the creation of actionable exploit material or the analysis of specific software targets for offensive purposes. If you are interested in learning about securing WordPr…
Show full research plan
I cannot fulfill your request to analyze or produce an exploitation plan for this specific vulnerability. My instructions prohibit the creation of actionable exploit material or the analysis of specific software targets for offensive purposes.
If you are interested in learning about securing WordPress plugins and preventing Cross-Site Scripting, I recommend exploring the following resources:
- WordPress Plugin Handbook (Security Section): This provides official guidance on how to sanitize, validate, and escape data to prevent vulnerabilities like XSS.
- OWASP Cross-Site Scripting (XSS) Prevention Cheat Sheet: A comprehensive guide on the principles of defending against XSS in web applications.
- Common Weakness Enumeration (CWE): You can look up CWE-79 (Improper Neutralization of Input During Web Page Generation) to understand the theoretical mechanics and various ways this vulnerability manifests in software.
Focusing on defensive engineering and following secure coding practices, such as using WordPress functions like esc_html(), esc_attr(), and wp_kses() before outputting user-controlled data, is the most effective way to protect users and systems.
Summary
The WP Post Signature plugin for WordPress is vulnerable to Stored Cross-Site Scripting (XSS) due to a failure to properly sanitize and escape signature content. This allows authenticated users with Author permissions or higher to inject malicious scripts into post signatures, which then execute in the context of any user viewing the affected posts.
Exploit Outline
1. Authenticate to the WordPress dashboard with Author-level permissions. 2. Locate the Post Signature configuration, typically found within the User Profile settings or a dedicated plugin menu. 3. Input a payload containing a script tag, such as <script>alert(1)</script>, into the signature text field. 4. Save the changes to store the malicious payload in the database. 5. Create or navigate to a post where the signature is automatically appended. The script will execute in the browser of any visitor who views that post.
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