You might find a user (e.g., robert or pdfuser ). Check their home directory:
: We construct a payload using backticks or a similar syntax designed to force the server to execute a reverse shell.
The application will generate a PDF. Download it and open it. You will see the contents of the /etc/passwd file rendered directly inside the PDF. Your flag will be within this content.
If you are stuck, try running similar PDF conversion tools (like wkhtmltopdf ) locally to see how they handle redirects.
When you launch the target container and access the web application via your browser, you are presented with a simple webpage containing an input form. The Web Interface pdfy htb writeup upd
If you closely look at the metadata generated within the output PDF or notice error codes triggered by invalid page parameters, you can identify the backend generation engine: .
cat /home/robert/user.txt
: Strictly validate user input using strict criteria that only permits standard http:// or https:// schemas, and reject responses from servers that attempt downstream redirection steps.
Create a simple PHP script named redirect.php on your attack machine. This script will force any visiting client to redirect to a local file or service on the target machine: Use code with caution. You might find a user (e
If you do not have a dedicated public VPS, you can spin up a quick Python/PHP server locally and expose it to the internet using tunneling services. In the Hack The Box community forums, users highly recommend lightweight options like Serveo to expose a local environment over the internet cleanly without being blocked by security warning screens:
Official PDFy Discussion - Challenges - Hack The Box :: Forums
user wants a long article for the keyword "pdfy htb writeup upd". This appears to be a request for a detailed write-up about a HackTheBox machine named "pdfy". The "upd" might be a typo or refer to "update". I need to gather comprehensive information. I'll search for "pdfy htb writeup", "pdfy hackthebox walkthrough", "pdfy htb", and "pdfy upd". search results show several write-ups for PDFy. Let's open them to gather details. have gathered several write-ups. The article should cover the challenge description, SSRF vulnerability, wkhtmltopdf exploitation, flag retrieval, and key takeaways. I'll structure the article with an introduction, reconnaissance, exploitation (including local file disclosure via redirect and SSRF via iframe), and conclusion. I need to cite the sources. Let's open the Axura write-up fully to get more details.'s also open the remaining parts of the Axura write-up. now have enough material to write the article. I'll structure it with sections on introduction, reconnaissance, exploitation, and conclusion. Now, I'll write the article. digital realm is filled with countless web challenges, but few are as elegant and instructive as , an "Easy" difficulty Web Challenge from Hack The Box (HTB). This challenge brilliantly simulates a real-world penetration testing scenario, focusing on the often-overlooked danger of trusting user-supplied URLs. At its core, PDFy is a lesson in how seemingly harmless features, like a 'website-to-PDF' service, can become a potent weapon in an attacker's hands. This comprehensive walkthrough will guide you through the complete process of pwning PDFy, from initial reconnaissance to crafting a multi-stage exploit that leaks sensitive system files, culminating in retrieving the flag. We'll explore the intricacies of SSRF (Server-Side Request Forgery) attacks, dissect a critical vulnerability in the popular wkhtmltopdf library, and even navigate the quirks of modern tunneling tools like ngrok to deliver the final payload. Whether you're a seasoned Capture The Flag (CTF) veteran or a curious newcomer, this write-up will provide you with a deep, hands-on understanding of a vulnerability class that remains alarmingly common in web development.
"url": "https://example.com"
wkhtmltopdf is a popular open‑source tool that renders HTML into PDF using the Qt WebKit engine. Versions prior to 0.12.6 are vulnerable to a Server‑Side Request Forgery (SSRF) attack, officially tracked as .
By using the PDF generator to read files via file:// and then exploiting pdftex for root, you can successfully root PDFY and capture both the UPD and RPD.
The author does an excellent job showcasing modern tooling: