Summary

Vulnerability: Stored DOM XSS via Blog Post Content (Persistent Payload Injection)

• Stored Cross-Site Scripting via Unsanitized Blog Post Content in Blog Management

Description

The application fails to properly sanitize user-controlled input when creating or editing blog posts. An attacker can inject a malicious JavaScript payload into blog post content, which is then stored server-side.

This stored payload is later rendered unsafely in multiple application views without proper output encoding, leading to stored cross-site scripting (XSS).

Affected Functionality

• Blog post creation functionality
• Blog post editing functionality
• Blog post storage and retrieval logic

Attack Scenario

• An attacker creates or edits a blog post to include a malicious XSS payload.
• The application stores this content without sanitization or encoding.
• The payload persists and executes whenever the blog post is rendered in affected views.

Impact

• Persistent Stored XSS
• Execution of arbitrary JavaScript in victims’ browsers
• Privilege escalation when viewed by administrators or privileged users
• Full administrator account takeover
• Full account takeover across all roles
• Full compromise of the entire application

Endpoints:

• /backend/blogs/create
• /backend/blogs/
• /blog/{id}

Steps To Reproduce (POC)

1. Go to the Blog Post Create or Edit page
2. Insert an XSS payload into the blog post content such as: <img src=x onerror=alert(document.domain)>
3. Save or publish the blog post
4. View the post via the administrative panel or public blog page
5. Notice the XSS payload executing automatically

Remediation

• Avoid unsafe DOM manipulation methods: Do not use .html(), innerHTML, or similar sink functions in client-side JavaScript or server-side templating (e.g., PHP). Even when user input flowing into these sinks is not immediately apparent, they can introduce Cross-Site Scripting (XSS) vulnerabilities that an attacker may exploit.

• Apply output encoding: Implement HTML entity encoding on all user-controlled data before rendering it in the browser. This helps neutralize potentially malicious input.

• Implement input sanitization: Ensure that all user-supplied input is properly sanitized before processing or output. Currently, no sanitization mechanisms are in place, which should be addressed as a priority.

• Enforce security headers and cookie attributes:

  • Content Security Policy (CSP): Define and enforce a strict CSP to limit the execution of unauthorized scripts.
  • HttpOnly flag: Set the HttpOnly attribute on session cookies to prevent client-side script access.
  • SameSite attribute: Configure the SameSite cookie attribute to mitigate Cross-Site Request Forgery (CSRF) risks.
  • Secure flag: Ensure all cookies are transmitted only over HTTPS by enabling the Secure attribute.

  These measures collectively reduce the impact of XSS and help prevent escalation paths such as CSRF via XSS.

Ready Video POC:

https://mega.nz/file/bYtCQRqT#ph1S_01XaYXiNTzanP3AVL6aQMe0YC5Py7Gko1FoT4A