Looper

Author: 1nt3rc3pt0r

Initial Analyisis

Looking at the challenge you can observe it geting redirected to and there exist a encoded flag() and and key is set to 1 at the localstorage of Browser which gives us the hint that used cipher to decode flag is vignere.

solution

So from our initial analysis we know we have to get a key to decode the cipher and the key is hidden in one of the requests.Now using the burpsuit we can navigate throught each and every requests starting from to at in the Script tag the key getting added to localstorage.

Now we have key and cipher text decoding them gives us the flag.