Engineering CTF Competition｜Design Engaging Challenges & Setup Efficiently

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How to Create an Engaging Engineering CTF Competition

Capture The Flag Competition Setup and Challenge Ideas

About CTF

Capture The Flag, abbreviated as CTF, is a sport originating from the West. It is commonly seen in modern paintball and first-person shooter games. The original concept involves teams protecting their own flags from being captured while trying to capture the flags of other teams. In the computer field, it refers to “offensive and defensive hacking battles,” where teams first find and protect their own vulnerabilities from intrusion, while simultaneously launching zero-delay attacks to capture points from other teams.

The above represents a standard, or even “advanced,” CTF competition format. Running a CTF competition within a company involves additional practical considerations:

1. The purpose of hosting a CTF competition, besides enhancing technical skills, is also to promote communication among engineers.

2. Engineers have different specialties, including Front-End, Back-End, APP, and DevOps; if you want everyone to participate, the questions should not focus too much on a specific field (e.g., networking, PHP).

3. Groups should balance strengths and evenly distribute domain expertise.

4. The event lasts at most one afternoon.

5. Organizing a CTF competition is a side project outside of the main work duties, with limited resources and time.

Considering all the above factors, rather than calling it a CTF competition, it is more like a:

Group Puzzle Solving to Earn Flag Points & Promote Interaction Among Engineers

A beginner-level CTF competition!

Event Objectives

1. Enhancing Engineering Skills

2. Promoting communication among engineers

3. Inspiring everyone’s passion and keen insight for exploration

4. Interesting things are fun; boring things are painful to do.

3 and 4 are my own additions. My expectations for this event go beyond practical aspects; I hope to boost everyone’s passion for exploring and learning new things in a fun way. Just like in daily work, we shouldn’t just be coders; we need to find ways to break through and keep moving forward!

Competition Rules

1. Divide engineers into groups evenly based on their expertise and strengths.

2. Competition Time: 90 minutes

3. There are a total of 12 questions, with 3 chances to spend points to buy hints.

4. Purchase cost decreases over time (the earlier you buy, the more expensive it is)

5. Each question has a base score plus a time bonus (the earlier you solve, the more points you get)

6. Once you start answering a specific question, you will be locked to only answer that question or other already opened questions; this continues until the question is passed or the lock time ends.
   (This rule exists because the activity mainly aims to encourage team members to communicate and brainstorm together, rather than dividing the work.)

7. The score per question, hint cost, and lock time vary according to the difficulty of the question.

8. Victory Condition: The highest cumulative score wins. If scores are tied, the faster completion time determines the winner.

9. The winning team has $$

How to Build?

After clarifying the event rules and objectives, the next key point is how to win a CTF competition?

This section is divided into two chapters: First, building a system capable of hosting CTF competitions, and Second, brainstorming competition challenges.

1. Building a System Capable of Hosting CTF Competitions

This part requires both front-end and back-end skills to implement. If you are not familiar, you will need to ask other colleagues for help.

Frontend: Semantic UI

Backend: PHP + JSON file for data storage

Due to limited time, the competition system was built with simplicity, stability, and speed in mind. The front-end interface directly uses the Semantic UI framework. The back-end is written in PHP without any framework. Data storage is handled using JSON files without a database. Keeping everything simple also reduces potential issues (such as someone trying to hack the system to get the answers).

Entry Page:

Starting with fun, the landing page uses references from the BBC series Sherlock:

Phone Unlock Password S H E R

These four input boxes are for entering the identification codes (4 digits) obtained by each group. For example, enter the first group: “1432”, the second group: “8421”, to identify which group will answer the questions.

As for the identification codes for each group, I added a little twist. The codes are displayed as follows:

Can you see the four-digit code? If not, please step back from the screen and take another look.

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Answer: The ID for the first group is 8291

After entering, you will go to the competition system homepage - problem list:

Displayed above: Team 1 group, remaining number of hint tickets

Middle Question Area: Question title, description, passing score, lock time, purchase hint, hint display

Mouse hover will display time score and suggested price

Displayed below: Total current score

Backend and Other Logic: The question list page uses Ajax every second to request the current answering status from the backend. The backend reads and records the answering status in each group’s JSON file. When unlocking a question, the time is recorded; questions cannot be unlocked before the set time. Upon passing a question, the completion time is recorded. Time scores and hint prices increase or decrease based on the time spent.

The competition system is roughly like this, but the focus is not on the system itself, but on the questions!

Is it interesting, can everyone participate, is it logical, is it novel… it’s really hard to come up with ideas

Let’s get straight to the point!

2. Competition Topic Ideation

First, I will introduce the five topics I have come up with.

1. The Gate to the Magic Academy

Problem Description: You will receive a key string. Use this key to decode the spell and enter it in the spell input box. Below, there is a captcha field that needs to be filled in. Press verify to submit your answer.

Answer:

This question tests cybersecurity and coding issues; it involves platform encryption and decryption vulnerability interfaces. If a website uses the same method and key for all encryption and decryption, we can exploit this weakness to decrypt the content and obtain the original data!

You can see the captcha part is ./image.php?token=AD0HbwdgVDw=. Here, a decryption interface is provided, so we can try using the above encryption key:

You will get the decrypted string: LiveALifeYouWillRemeber

Enter it into the spell input box to clear the level!

2. Please take me back to Shanghai in 1937!

Problem Description: You need to find a way to input year/month/day and submit it to the backend so that the backend recognizes the year as 1937; the input year range (1947~2099) does not allow directly entering 1937.

Answer:

This question is not about bypassing front-end validation, as the back-end handles it and cannot be bypassed. The main focus is on the 32-bit computer Year 2038 problem. Due to the 32-bit limit, the timestamp can only represent dates up to January 19, 2038, 03:14:07. Beyond this, it will overflow and reset to January 1, 1901. Therefore, by inputting dates from 2073–02–06 to 2074–02–05, the system will interpret them as dates in 1937. Entering dates within this range will allow successful submission!

Wikipedia

3. The Duel of Wits

Problem Description: Find a way to intercept a password reset email sent to a third party’s email account (which you cannot log into) and complete the password reset for that person.

Answer:

This task requires more sensitivity. First, use an email account you can access to reset the password; the email we received is as follows:

Your password reset link: http://ctf.zhgchg.li/10/reset.php?requestid=OTk= If this is not related to you, please ignore this message. Thank you!

We can see that the password reset request is identified through the parameter requestid. The value we got is OTk=, which looks like base64? Let’s try it:

base64 decode and encode

We can get the parameter value as 99, then repeat the password reset request to get 100. Therefore, it can be inferred that the password reset requests are sequential numbers, with the next being 101. At this point, returning to the original email to bypass and pressing the reset password request, we can forge and combine the password reset link ourselves, thus secretly resetting someone else’s password.

Encode 101 in Base64 => MTAx. Fake URL: http://ctf.zhgchg.li/10/reset.php?requestid=MTAx. Enter any password and click reset to pass!

4. Vest Master

Task Description: You need to create 10 sets of Gmail accounts (Gmail hosted mailboxes) to receive answer emails.

Answer:

Of course, this problem can be brute-forced, but company email accounts cannot be registered casually; unless you find 10 people to help receive emails, it cannot be solved.

The key point here is the Gmail mailbox / Gmail hosted mailbox. Since the company mailbox is a Gmail hosted mailbox, it also has the features of a Gmail mailbox: you can use “.” and “+” to create unlimited alias addresses. The “.” can be placed anywhere in the username, and the “+” can be placed at the end followed by any numbers.

For example: The main mailbox is zhgchgli@gmail.com, but emails sent to z.hgchgli@gmail.com, zh.gchgli@gmail, zhgchgli+1@gmail.com, zhgchgli+25@gmail.com, and so on will all be delivered to the main mailbox zhgchgli@gmail.com. One mailbox can create multiple identities!

This article mainly reminds everyone to filter out these characters during account registration to prevent malicious users from creating大量fake accounts.

After collecting 10 letters, you can assemble the URL containing the answer. Enter the URL to clear the level!

5. Time Machine

Problem Description: Similar to question 3 “Face/Off,” you need to find a way to intercept a third party’s (you cannot receive their SMS) mobile SMS verification code (4-digit number) to log into someone else’s account.

Answer:

This problem is relatively obscure and difficult, mainly simulating a side-channel timing attack. The system login verification involves a complex algorithm, and there is a time difference when processing verification information (for example: processing one correct digit takes longer, while a completely wrong input returns immediately and quickly). By observing these time differences, we start from 0000 and try each digit one by one. When trying 2000, we notice it takes one second to process, indicating the first digit is 2. Continuing with 2100, it still takes one second, but 2200 takes even longer—two seconds. By further testing the third and fourth digits, we eventually obtain the correct answer: 2256.

This example only simulates this type of attack. The backend processing uses sleep to mimic the delay without actual complex algorithms. Such attacks are rarely encountered in web or app environments. On one hand, the processing is not complex enough to cause noticeable time differences; on the other hand, network factors also affect timing, making it difficult to judge.

For detailed information about side-channel attacks, please refer to this article:

](/assets/729d7b6817a4/1*SF1S_RZNTI-5ZaC3Kw1Ypw.webp){: lqip=”data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHdpZHRoPSIxNDAwIiBoZWlnaHQ9IjkwNSI+PHJlY3Qgd2lkdGg9IjEwMCUiIGhlaWdodD0iMTAwJSIgZmlsbD0iZ3JleSIvPjwvc3ZnPg==” }

Understand CORB in 30 Minutes — Side-Channel Attacks

The above are the 5 questions I came up with. Below are the remaining 7 questions provided by my colleagues.

1. Sadako Appearance

Sadako image sourced from the internet

Problem Description: The problem is an image of Sadako. You need to enter what Sadako wants to say in the input box above to pass.

Answer:

This question tests whether you know that images can contain other information. The key lies in the original version of this image:

Sadako image sourced from the internet

This image has secretly compressed a text file inside it (for the actual method, please refer to: How To Hide A ZIP File Inside An Image On Mac [Quicktip] , note the Win/Mac compatibility issues here)

So we only need to simply unzip the Commone image to get the passcode string:

Enter “YOUHAVENOIDEA” in the input box to pass!

Supplement:

Regarding hidden information in images, there is another method using “Image Steganography”.

Image Steganography and Malware: Principles and Methods

Simply put, it manipulates the pixel color values to hide information. The actual image changes, but the difference is invisible to the naked eye.

I was worried everyone would take this approach, so I hid a code in the image. Those who follow this path can get a hint:

Steganography Online

Upload the image to an online steganography decoding tool to get the hint.

2. Caesar’s Morse Code

The images are sourced from the internet.

Problem Description: Decode the given Morse code to find the hidden message (an English sentence).

Answer:

This question is quite straightforward. The first step is to decode the Morse code into the English letters “VYYXI DN HT GDAZ”.

Morse Code Translator

Then perform a Caesar cipher decryption. When we try a shift of 5, we get a meaningful English sentence: “addcn is my life,” which is the answer!

Caesar Cipher Decryption Tool

3. What do you think it is?

Opening the webpage for this question shows a lot of garbled text, as follows:

data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAA...

Problem Description: Find the answer from this jumble of characters.

Answer:

This question is actually quite straightforward and doesn’t require much thought; frequent coders should recognize this jumble as a base64 string. Let’s first decode it, and we get:

data:image/png;base64,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

From the beginning, it is clear that this is a base64 compressed image. By pasting the above code directly into the browser’s address bar, you can get the URL with the answer. Enter the URL to pass the challenge!

4. Breaking Through the Blockade

Problem Description: This problem immediately shows the PHP code. You need to find a way to bypass the condition using GET parameters to execute the setPassedCookie() method inside the else block.

Solution: This is a commonly used but little-known PHP vulnerability, detailed as follows:

Summary of Common PHP Vulnerabilities in CTF

The question has been slightly modified. The answer to this question is: ?m.id[ ]=admin

5. The Test of Penetration, 6. The Test of Penetration 2

These two questions are basic introductory XSS problems, so no further explanation will be given here.

Since the solution is placed on the frontend, this uses a JS website that provides irreversible encryption: https://www.sojson.com/jsobfuscator.html

(Although I’m not sure if it’s true, if there’s a way to crack it, let’s just consider it passed!)

7. Moonlight Treasure Box

This question is taken from a puzzle app and will not be shown here.

Summary

The competition system took about a week to build, and the questions took around three months to gradually gather (inspiration was needed). The competition has successfully concluded, and the feedback has been quite positive—”fun and enjoyable.” This was my original intention: to have everyone explore and brainstorm starting from a point of fun. Therefore, neither the question titles (which are all very cinematic) nor the question directions involve deep engineering or complex calculations, as that would be too rigid and not fun!

Additionally, here is the question response rate for reference on difficulty:

When creating the questions, the biggest fear was that they would be too easy and everyone would finish quickly, or too hard and everyone would get stuck. Both situations are awkward.

The actual competition results (duration: 90 minutes) matched our expectations perfectly! It was neither too hard nor too easy. The first-place team solved 9 problems, while even the last-place team solved 7 problems. The scores were very close, but factors like time and hint purchases ultimately determined the final rankings!

Surprisingly, no one has solved the entrance to the Magic Academy… QQ

The above is the complete summary of this engineering CTF competition.

Addcn 2019 CTF

Further Reading

• Revealing a Clever Website Vulnerability Discovered a Few Years Ago

• The app uses HTTPS for transmission, but data was still stolen

If you have any questions or feedback, feel free to contact me.

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