In the realm of ancient codes, only those who enumerate correctly can unveil the hidden flag. Craft your mathematical expressions wisely and uncover the secrets that lie within.
Flag Format: KCTF{FLaG_HeRe}
🎯 Challenge Files & Infrastructure
Provided Files
1
Files:None
🔍 Initial Analysis
First Steps
Initially, the website appears as follows:
Site Presentation
by trying to enter something in the numeric input box and submitting, I get letters in the file name:
Submit Try
so, I assume it’s about finding the correct combination to print the contents of the file flag.txt.
🎯 Solution Path
Exploitation Steps
Initial setup
After understanding how it works, I moved on to the exploit, doing a bit of guessing on the letters to figure out which number corresponded to which letter.
Exploitation
After a couple of attempts, I came up with this:
Second Attempt
continuing to experiment, I found the correct combination, 7195, which allowed me to read the flag.txt file.
Flag capture
Manual Flag
🛠️ Exploitation Process
Approach
The exploit is very simple: it’s a POST request to the page where I pass the parameter expression=7195, which is the correct combination. Then, I extract the flag from the response text using bs4:
