FriendSpaceBookPlusAllAccessRedPremium | Google CTF 2019

Google CTF 2019

FriendSpaceBookPlusAllAccessRedPremium

Having snooped around like the expert spy you were never trained to be, you found something that takes your interest: “Cookie/www.FriendSpaceBookPlusAllAccessRedPremium.com” But unbeknownst to you, it was only the 700nm Wavelength herring rather than a delicious cookie that you could have found. It looks exactly like a credential for another system. You find yourself in search of a friendly book to read. Having already spent some time trying to find a way to gain more intelligence… and learn about those fluffy creatures, you (several)-momentarily divert your attention here. It’s a place of all the individuals in the world sharing large amounts of data with one another. Strangely enough, all of the inhabitants seem to speak using this weird pictorial language. And there is hot disagreement over what the meaning of an eggplant is. But not much Cauliflower here. They must be very private creatures. SarahH has left open some proprietary tools, surely running this will take you to them. Decipher this language and move forth!

Attachement

You can find my all CTF solution in here

When I download the Attachment I saw two file. One of them is python script another of them is tex file.

vm.py

program

The program file is such as Stack-based VM

So first we must understand the code. I executed the python script with the program.

Its try to extract website and this getting slower. I think decoding program is starting to complex. So that I must to find way wat to decode program.

I forget to mention about the stact-based vm. These program is need accumulator (1,2) and stact to executation and instruction pointer to know where the code.

So I try to print that value before the print char.

I added this below code in print_top() function

Output is:

when I look at it

before the calculation new char program executed XOR operation between acc1 and end of the stack

Also when we loak at the operation list and program it is show the before the print_top operation always xor happens

I can put the print function before the XOR happens

Output is:

When I search the ACC1: serieas I figure out the this is a Palindromic primes. I found the python code in the https://oeis.org/A002385

After that I write all ACC1 value and index value you can find index values in program file. End of the ACC1 values it shows the index value

After that I write the python code the extract website

When I run the program

It gives the address.

In that website you can find the flag in Amber profile

http://emoji-t0anaxnr3nacpt4na.web.ctfcompetition.com/humans_and_cauliflowers_network/

That is the FLAG:

CTF{Peace_from_Cauli!}

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