Category: Reversing Points: 200 Solves: 108 Description:

Last month I was trying to simplify an algorithm.. and I found how to mess up a source really really bad. And then this challenge is born. Maybe is really simple or maybe is so hard that all of you will give up. Good luck!



Another binary reversing problem. This one is a dynamically linked 32-bit ELF with symbols stripped. A look at strings does not give us any useful information. The binary itself, when run, appears to wait for input, perform some sort of check, then tell you if it's correct or not. An ltrace indicates that there's no useful function calls that will help us better understand what's going on. Lets start by looking at the location of the gets call.

Category: Pwnable Points: 150 Solves: 86 Description:

Do you like reading books? here we have the best collection ever! you can even save some books for future reading!! enjoy noob!

GPG key: yowlijOshSuftEvawvIshgugdecWikBi


For this challenge, we're given a file named "johns-library". That is a 32-bit unstripped ELF file. Strings doesn't give us much info. Let's run it and see what happens.

We get presented with the following challenge:

John bets nobody can find the passphrase to login!

GPG key: viphHowrirOmbugTudIbavMeuhacyet'



The file extracts to an apk (Android package file). Running strings on it doesn't give us any insight into what's going on. Let's load it into Genymotion: