CS211-Assignment 3 Bomb Lab Solved

The purpose of Programming Assignment 3 (PA3) is for you to become familiar with x86IA32 Instruction Set Architecture (ISA). The nefarious Dr. Evil has planted a slew of binary bombs on our machines. A binary bomb is a program that consists of a sequence of phases. Each phase expects you to type a particular string on stdin. If you type the correct string, then the phase is defused and the bomb proceeds to the next phase. Otherwise, the bomb explodes by printing BOOM!!! and then terminating. The bomb is defused when every phase has been defused. There are too many bombs for us to deal with, so we are giving everyone a bomb to defuse. Your mission, which you have no choice but to accept, is to defuse your bomb before the due date. Good luck, and welcome to the bomb squad!

1           Instruction
The bombs were constructed specifically for 32-bit machines and Linux operating system. You must do this assignment only on the iLab machines. You will not defuse the bomb otherwise and will not get credit.

Open an Internet Browser and go to the URL: http://assembly.cs.rutgers.edu:17200

This address is only visible when you are connected in the Rutgers Network. Fill the form up with your NetID and your email address to get your bomb package. The file that you will get is in the format bombN.tar, where N is your bomb ID, i.e. ID. If you havent downloaded it in the iLab machines, copy the file to there and untar your bomb into your home directory. You are not allowed to download no more than two bombs. Copy the bomb that you downloaded into your iLab account and work with it.

$ tar -xvf bombID.tar
It will create a directory bombID that should contain the following files:

1.    bomb: The executable binary bomb

2.    bomb.c: Source file with the bombs main routine

3.    README: File with the bomb ID and extra information

Your job is to defuse the bomb. You can use many tools to help you with this; please look at the tools section for some tips and ideas. The best way is to use a debugger to step through the disassembled binary. The bomb has 9 phases. The phases get progressively harder to defuse, but the expertise you gain as you move from phase to phase should offset this difficulty. Nonetheless, the latter phases are not easy, so please dont wait until the last minute to start. The bomb ignores blank input lines. If you run your bomb with a command line argument, for example, $ ./bomb mysolution.txt

then it will read the input lines from mysolution.txt until it reaches EOF (end of file), and then switch over to stdin (standard input from the terminal). In a moment of weakness, Dr. Evil added this feature so you dont have to keep retyping the solutions to phases you have already defused. To avoid accidentally detonating the bomb, you will need to learn how to single-step through the assembly code and how to set breakpoints. You will also need to learn how to inspect both the registers and the memory states. One of the nice side-effects of doing the lab is that you will get very good at using a debugger. This is a crucial skill that will pay big dividends the rest of your career.