How to Create a Fun 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 paintball and first-person shooter games today. The original concept involves teams protecting their own flags from being captured while trying to capture the flags of other teams. In the computing field, it translates to “attack and defense battles,” where teams first find and secure their own vulnerabilities to prevent intrusions, while simultaneously launching zero-day attacks to steal points from other teams.
The above represents a standard, even “advanced,” CTF competition style. Running a CTF competition within a company also involves other practical considerations:
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The purpose of hosting a CTF competition, besides improving technical skills, is also to promote communication among engineers.
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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).
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Groups should balance strengths and evenly distribute expertise across domains.
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The event lasts at most one afternoon.
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Organizing a CTF competition is a side project outside 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:
Team Puzzle Solving to Accumulate Flag Points & Promote Communication Among Engineers
An entry-level CTF competition!
Event Goals
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Enhancing engineering skills
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Promoting communication among engineers
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Inspiring everyone’s passion and curiosity for exploration
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Fun activities are enjoyable; boring ones are painful to do
3 and 4 were added by myself. My expectations for this event go beyond practical skills; I hope to boost everyone’s enthusiasm for exploring and learning new things in a fun way. Just like daily work, we shouldn’t just be code monkeys but strive to break through and keep moving forward!
Competition Rules
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Divide engineers into balanced groups based on their expertise and strengths.
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Competition Time: 90 minutes
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There are a total of 12 questions, with 3 chances to purchase hints using points.
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Hint purchase cost decreases over time (the earlier you buy, the more expensive it is)
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Each question has a base score plus a time score (the earlier you solve, the more points you get)
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Once a challenge is opened for answering, participants can only submit answers for that challenge or other already opened challenges until the challenge is solved or the lock time expires.
(This rule exists because the event aims to encourage team members to collaborate and brainstorm together, rather than divide and conquer the challenges.) -
Each question’s score, hint cost, and lock time vary according to the difficulty level.
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Victory Conditions: The team with the highest total score wins. If scores are tied, the team with the shorter total solving time wins.
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Winning teams have $$
How to Build?
After clarifying the rules and goals, the next big question is how to run a CTF competition?
This section is divided into two chapters: first, building a system capable of hosting a CTF competition, and second, brainstorming the competition challenges.
1. Building a System for CTF Competitions
This part requires frontend and backend skills to implement. If you’re not familiar, you’ll need to ask other colleagues for help.
Frontend: Semantic UI
Backend: PHP + JSON file data storage
Due to limited time, the competition system was built to be simple, stable, and fast. The frontend directly uses the Semantic UI framework. The backend is written in plain PHP without any framework, and data is stored directly in JSON files without using a database. Keeping everything simple also reduces potential issues (such as someone attacking the system to get the answers).
Entry Page:
Starting with fun as the theme, the entry page uses a reference from the BBC series Sherlock:
Phone Unlock Password S H E R
These four input boxes are used to enter each team’s identification code (4 digits). For example: enter “1432” for Team 1, “8421” for Team 2, to identify which team is answering the questions.
As for each team’s identifier, I added a little twist. The identifiers are displayed as follows:
Have you spotted the four-digit code? If not, please step away from the screen and take another look.
請提供您要翻譯的 Markdown 段落內容，謝謝！
請提供您要翻譯的 Markdown 段落內容，謝謝！
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…………………………….
………………………………….
……………………………..
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Please provide the Markdown paragraphs you want me to translate into English.
請提供您想翻譯的 Markdown 文章段落內容，我將依照您的要求進行翻譯。
請提供您要翻譯的 Markdown 段落內容，謝謝！
..
Answer: The first group’s identification code is 8291
After logging in, you will enter the main page of the competition system - the problem list:
Displayed above: Team 1 group, remaining hint tickets
Middle Challenge Area: Challenge name, description, points awarded upon completion, lock time, hint purchase, hint display
Mouse hover shows time score and hint price
Displayed below: Total current score
Backend and Other Logic: The question list page requests the current answering status from the backend every second via Ajax. The backend reads and records the answering status in each group’s JSON file. When unlocking a question, it records the time; 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 challenges!
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. Ideas for Competition Challenges
First, I will introduce the five problems I designed.
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 is a captcha field that must be filled in. Press verify to submit your answer.
Answer:
This challenge tests cybersecurity and encoding issues; it involves exploiting encryption and decryption vulnerabilities on the platform. If the website uses the same method and key for all encryption and decryption, we can use 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 inputting the encryption key above:
You will get the decrypted string: LiveALifeYouWillRemeber
Enter it into the spell input box to pass!
2. Take me back to Shanghai in 1937!
Challenge Description: You need to find a way to input the year/month/day and submit it to the backend so that it is recognized as the year 1937; direct input of the year 1937 is not allowed within the input range (1947~2099).
Answer:
This challenge is not about bypassing frontend validation, as the backend handles it and cannot be bypassed. The main focus is the 32-bit 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 back to January 1, 1901. Therefore, by inputting dates from 2073–02–06 to 2074–02–05, which correspond to 1937 after overflow, the submission will succeed!
3. Clash of Wits
Problem Description: Figure out how to receive a password reset email from a third party (an email account you cannot log into) and reset someone else’s password.
Answer:
This challenge requires more attention to detail. First, use an email address 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 by the parameter requestid. The value we got is OTk=, which looks like base64? Let’s give it a try:
We can get the parameter value as 99, then repeat the password reset request to get 100. Therefore, we can infer that the password reset requests use sequential numbers, and the next number is 101. At this point, returning to the original email to bypass and request a password reset, we can forge and combine the reset link ourselves, allowing us to secretly reset someone else’s password.
Encode 101 to Base64 => MTAx, forge the URL: http://ctf.zhgchg.li/10/reset.php?requestid=MTAx, enter any password and press reset password to pass!
4. Vest Master
Problem Description: You need to create 10 sets of Gmail accounts (Gmail hosted mailboxes) to receive answer emails.
Answer:
This challenge can of course be brute-forced, but company email accounts cannot be registered freely; unless you find 10 people to receive emails for you, you won’t be able to solve it.
The key to this challenge is the Gmail mailbox/Gmail hosted mailbox. Since the company mailbox is a Gmail hosted mailbox, it has Gmail’s features: 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 [email protected], but emails sent to [email protected], zh.gchgli@gmail, [email protected], [email protected]… will all arrive at the main mailbox [email protected]. One mailbox can create multiple identities!
This section mainly reminds everyone to filter out these characters during account registration to prevent malicious users from creating大量 fake accounts.
Collect all 10 emails to assemble the URL containing the solution. Once you enter the URL, you can complete the challenge!
5. Time Machine
Challenge Description: Similar to Challenge 3 “Face/Off,” you need to find a way to intercept a third party’s (you cannot intercept SMS messages yourself) phone SMS verification code (4 digits) to log into someone else’s account.
Answer:
This challenge is uncommon 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 the verification data (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, indicating the first digit is 2. Continuing with 2100 still takes one second, and 2200 takes even longer—two seconds. By further testing the third and fourth digits, we eventually obtain the correct answer: 2256.
This challenge only simulates this kind of attack. The backend uses sleep to mimic it without any complex actual algorithms. Such attacks are rarely encountered in web or app environments. On one hand, the processed information is usually not complex enough to cause noticeable time differences; on the other hand, network factors also affect timing, making it hard to judge.
For more details on side-channel attacks, please refer to this article:
Understanding CORB in 30 Minutes — Side-Channel Attacks
The above are the 5 problems I came up with. Below are the remaining 7 problems provided by my colleagues.
1. Sadako Appearance
The Sadako image is taken from the internet
Challenge Description: The challenge is an image of Sadako. Enter what Sadako wants to say in the input box above to pass.
Answer:
This question tests whether you know that images can contain hidden information. The key lies in the original version of this image:
The Sadako image is taken 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 differences between Windows and Mac here.
So we just need to simply unzip the “Commone” image to get the passphrase:
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, the pixel color values are manipulated to hide information. The actual image changes, but it is indistinguishable to the naked eye.
This challenge might lead everyone in this direction, so hidden codes were also embedded in the image. Those who take this path can receive a hint:
Upload the image to an online steganography decoding tool to get a hint.
2. Caesar’s Morse Code
The images are sourced from the internet.
Challenge Description: Decode the Morse code provided in the challenge 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 “.
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!
3. What do you think it is?
Opening the webpage for this challenge shows a bunch of garbled text, as follows:
data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAA... (truncated for brevity)
Challenge Description: Find the answer from this pile of gibberish.
Answer:
This challenge is actually quite straightforward and doesn’t require overthinking; frequent users of encoding should recognize that this jumble of characters is just a base64 string. Let’s first decode it, and we get:
data:image/png;base64,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
From the beginning, we know this is a base64 compressed image. We can paste the above encoding directly into the browser’s address bar to get the answer URL. Entering the URL will allow you to pass!
4. Breaking Through the Blockade
Problem Description: This challenge 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 explanation is as follows:
Common PHP Vulnerabilities in CTF
The question has been slightly modified. The answer to this question is: ?m.id[]=admin
5. Penetration Challenge, 6. Penetration Challenge 2
These two questions are basic introductory XSS challenges, so no further explanation is provided here.
This challenge has its solution placed on the frontend, using a JS website that provides irreversible encryption: https://www.sojson.com/jsobfuscator.html
(Although I’m not sure if it’s true? Anyway, if it can be cracked, 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, while the questions were slowly gathered over three months (inspired by creativity). The event has successfully concluded with positive feedback—“fun and enjoyable.” This was my original intention: to encourage everyone to explore and brainstorm starting from a fun perspective. Therefore, neither the question titles (which are all very cinematic) nor their directions involve deep engineering or complex calculations, as that would be too rigid and boring!
Additionally, here are the question response rates for reference on difficulty:
When creating the questions, the biggest fear was that the problems would be too easy and everyone would solve them quickly, or too hard and everyone would get stuck. Both situations are quite awkward.
The actual competition results (duration: 90 minutes) met our expectations perfectly! The difficulty was just right—not too hard or too easy. The first-place team solved 9 challenges, while even the last-place team solved 7; very close. However, due to time scoring and hint purchases, the final rankings were still clearly determined!
Surprisingly, no one managed to solve the gate to the Magic Academy… QQ
This concludes the overall summary of the engineering CTF competition held this time.
Addcn 2019 CTF
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