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In this writeup I will be exploring the cryptographic challenges within OWASP Juice Shop.

Here is a list of challenges solved in this writeup:

Weird Crypto

Difficulty: Moderate -> Trivial

Nested Easter Egg

Difficulty: Moderate

Forged Coupon

Difficulty: Advanced

Nested Easter Egg

Confidential Document

While trying to read the confidential document we come across this /ftp directory, which we will visit for the next section.

From the /ftp directory there is an interesting document titled ’eastere.gg’. I tried to click on this, but received an error stating that only .md and .pdf files are allowed.

we can add a URL encoded null byte in the address bar and then append the .md to make the server think we are asking for one of the valid file types.

I opened the file in notepad++ and found the next step in the puzzle:

The string “L2d1ci9xcmlmL25lci9mYi9zaGFhbC9ndXJsL3V2cS9uYS9ybmZncmUvcnR0L2p2Z3V2YS9ndXIvcm5mZ3JlL3J0dA==”

The fact that this ends in a double equal indicates that this is base64 encoded.

I plugged this into cyberchef, and the output looks like a directory path, but not a human readable one…

After trying some different decoding methods, I found that Rot13 cypher returned something that looks like a valid path.

Finally I went back to juice shop and pasted in this path and found a strange planet.

After tweaking the settings on the page I was able to see the symbol on the planet seems to be some sort of plant!

Returning to the score board I found that the challenge was now solved.

Weird Crypto

The weird crypto challenge had me stumped for a while, as I wasn’t sure what the question was asking for. However, after solving the Easter egg challenge, I deccided to click the link they provided which goes to the customer feedback page.

I simply informed them that they should not be using such insecure encryption as Rot13, and the challenge was solved!

Forged Coupon

As we found earlier, we can just download any of the files in the /ftp directory by adding a null byte and appending the accepted file type

%2500.md

I was looking through the files and downloaded the coupons_2013.md.bak file and found a list of gibberish.

Note: I am still working on the rest of the challenges for this writeup