If you are running this locally, you must expose your server to the internet so the HTB challenge instance can reach it. Using a Reverse Proxy or tools like Serveo is recommended over ngrok for this specific challenge to avoid browser warning screens that might break the automated PDF rendering.
This writeup explores , a web-based Hack The Box (HTB) challenge categorized as "Easy." This challenge is a classic introduction to Server-Side Request Forgery (SSRF) , demonstrating how an application that renders web pages into PDFs can be coerced into leaking sensitive internal files. Challenge Overview Category: Web Difficulty: Easy
This is a known command-line tool that uses the WebKit rendering engine to convert HTML to PDF. Crucially, older versions of this tool are vulnerable to SSRF because they follow redirects and execute JavaScript. pdfy htb writeup upd
Official PDFy Discussion - Page 2 - Challenges - Hack The Box
You need a way to serve a 302 Redirect . You can use a simple PHP script or a Python server to achieve this. Use code with caution. Step B: Expose Your Server If you are running this locally, you must
Download the resulting PDF. Inside, you will see the text content of the server's password file. Scroll through the entries to find the HTB flag, which is typically appended as a comment or a user entry.
Always validate and sanitize user-provided URLs. Blacklisting "localhost" or "file://" is rarely sufficient, as redirects can often bypass these filters. Challenge Overview Category: Web Difficulty: Easy This is
By inspecting the metadata of the generated PDF files (using tools like exiftool or by looking at the PDF's properties), you can identify the backend engine: .
If using wkhtmltopdf in production, ensure it is updated and configured with --disable-local-file-access to prevent this exact type of leak.
Entering a standard URL like http://google.com confirms the functionality—the application fetches the page and returns a PDF version of it.