Writeup For Ph4nt0m 1ntrud3r

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Introduction

Ph4nt0m 1ntrud3r is a challenging and intriguing challenge from PicoCTF2025, designed to test the skills of participants in the realm of web exploitation and reverse engineering. In this writeup, we will delve into the intricacies of the challenge, exploring the vulnerabilities and techniques used to bypass security measures and ultimately obtain the flag.

Challenge Overview

Ph4nt0m 1ntrud3r is a web-based challenge that presents a seemingly innocuous login page. However, upon closer inspection, it becomes apparent that the page is vulnerable to a range of attacks, including SQL injection and cross-site scripting (XSS). The challenge requires participants to exploit these vulnerabilities to gain access to sensitive information and ultimately obtain the flag.

Initial Analysis

Upon visiting the login page, we are presented with a simple form containing a username and password field. The page appears to be using a standard login mechanism, with the username and password being sent to the server for verification. However, upon inspecting the HTML source code, we notice that the page is using a JavaScript library to handle the login functionality.

<script src="https://cdn.jsdelivr.net/npm/jquery@3.6.0/dist/jquery.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/jquery-cookie@1.4.1/jquery.cookie.min.js"></script>

This suggests that the page is using a combination of JavaScript and server-side code to handle the login functionality.

Identifying Vulnerabilities

Upon further analysis, we identify two primary vulnerabilities in the challenge:

  1. SQL Injection: The login page is vulnerable to SQL injection attacks, allowing an attacker to inject malicious SQL code into the database. This can be achieved by manipulating the username and password fields to inject malicious SQL code.
  2. Cross-Site Scripting (XSS): The page is also vulnerable to XSS attacks, allowing an attacker to inject malicious JavaScript code into the page. This can be achieved by manipulating the username and password fields to inject malicious JavaScript code.

Exploiting Vulnerabilities

To exploit the SQL injection vulnerability, we can use a tool such as Burp Suite to intercept and modify the HTTP requests sent to the server. We can then inject malicious SQL code into the database to retrieve sensitive information.

SELECT * FROM users WHERE username = 'admin' AND password = 'password'

To exploit the XSS vulnerability, we can use a tool such as Burp Suite to intercept and modify the HTTP requests sent to the server. We can then inject malicious JavaScript code into the page to retrieve sensitive information.

var xhr = new XMLHttpRequest();
xhr.open('GET', '/flag', true);
xhr.send();

Bypassing Security Measures

To bypass the security measures in place, we can use a range of techniques, including:

  1. User-Agent Spoofing: We can spoof the User-Agent header to make the server believe that the request is coming from a legitimate browser.
  2. Cookie Tampering: We can tamper with the cookies sent to the server to bypass authentication checks.
  3. Request Forgery: We can forge requests to the server to bypass authentication checks.

Obtaining the Flag

Once we have exploited the vulnerabilities and bypassed the security measures, we can obtain the flag by retrieving the sensitive information from the database or by executing malicious JavaScript code on the page.

<div id="flag">Congratulations, you have obtained the flag!</div>

Conclusion

Ph4nt0m 1ntrud3r is a challenging and intriguing challenge that requires participants to use a range of skills, including web exploitation and reverse engineering. By exploiting the SQL injection and XSS vulnerabilities, and bypassing the security measures in place, we can obtain the flag and demonstrate our skills in the realm of web exploitation.

Recommendations

Based on our experience with Ph4nt0m 1ntrud3r, we recommend the following:

  1. Practice Web Exploitation: Web exploitation is a critical skill for any security professional, and practicing it regularly can help improve your skills.
  2. Use Burp Suite: Burp Suite is a powerful tool for web exploitation, and using it can help you identify and exploit vulnerabilities in web applications.
  3. Stay Up-to-Date with Security Research: Staying up-to-date with the latest security research and techniques can help you stay ahead of the curve and improve your skills.

Final Thoughts

Ph4nt0m 1ntrud3r is a challenging and intriguing challenge that requires participants to use a range of skills, including web exploitation and reverse engineering. By exploiting the SQL injection and XSS vulnerabilities, and bypassing the security measures in place, we can obtain the flag and demonstrate our skills in the realm of web exploitation. We hope that this writeup has provided valuable insights and information for participants, and we look forward to seeing what the future holds for web exploitation and security research.

Introduction

Ph4nt0m 1ntrud3r is a challenging and intriguing challenge from PicoCTF2025, designed to test the skills of participants in the realm of web exploitation and reverse engineering. In this Q&A guide, we will address some of the most frequently asked questions about the challenge, providing valuable insights and information for participants.

Q: What is Ph4nt0m 1ntrud3r?

A: Ph4nt0m 1ntrud3r is a web-based challenge that presents a seemingly innocuous login page. However, upon closer inspection, it becomes apparent that the page is vulnerable to a range of attacks, including SQL injection and cross-site scripting (XSS).

Q: What are the primary vulnerabilities in Ph4nt0m 1ntrud3r?

A: The primary vulnerabilities in Ph4nt0m 1ntrud3r are SQL injection and cross-site scripting (XSS). These vulnerabilities can be exploited to gain access to sensitive information and ultimately obtain the flag.

Q: How can I exploit the SQL injection vulnerability?

A: To exploit the SQL injection vulnerability, you can use a tool such as Burp Suite to intercept and modify the HTTP requests sent to the server. You can then inject malicious SQL code into the database to retrieve sensitive information.

Q: How can I exploit the XSS vulnerability?

A: To exploit the XSS vulnerability, you can use a tool such as Burp Suite to intercept and modify the HTTP requests sent to the server. You can then inject malicious JavaScript code into the page to retrieve sensitive information.

Q: What are some common techniques used to bypass security measures in Ph4nt0m 1ntrud3r?

A: Some common techniques used to bypass security measures in Ph4nt0m 1ntrud3r include:

  • User-Agent spoofing
  • Cookie tampering
  • Request forgery

Q: How can I obtain the flag in Ph4nt0m 1ntrud3r?

A: To obtain the flag in Ph4nt0m 1ntrud3r, you can exploit the SQL injection and XSS vulnerabilities, and bypass the security measures in place. Once you have done this, you can retrieve the sensitive information from the database or execute malicious JavaScript code on the page.

Q: What are some best practices for web exploitation and reverse engineering?

A: Some best practices for web exploitation and reverse engineering include:

  • Practicing web exploitation regularly
  • Using tools such as Burp Suite to identify and exploit vulnerabilities
  • Staying up-to-date with the latest security research and techniques

Q: What are some common mistakes to avoid when exploiting Ph4nt0m 1ntrud3r?

A: Some common mistakes to avoid when exploiting Ph4nt0m 1ntrud3r include:

  • Failing to identify and exploit the SQL injection and XSS vulnerabilities
  • Failing to bypass the security measures in place
  • Using outdated or insecure tools and techniques

Q: How can I get help with Ph4nt0m 1ntrud3r?

A: If you are having trouble with Ph4nt0m 1ntrud3r, you can try the following:

  • Check the official PicoCTF2025 documentation and resources
  • Ask for help on the PicoCTF2025 forums or Discord channel
  • Reach out to a mentor or experienced participant for guidance

Conclusion

Ph4nt0m 1ntrud3r is a challenging and intriguing challenge that requires participants to use a range of skills, including web exploitation and reverse engineering. By exploiting the SQL injection and XSS vulnerabilities, and bypassing the security measures in place, we can obtain the flag and demonstrate our skills in the realm of web exploitation. We hope that this Q&A guide has provided valuable insights and information for participants, and we look forward to seeing what the future holds for web exploitation and security research.