CS 2400, Fall 2013 Lab Assignment L2: Defusing a Binary Bomb 1 Introduction 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 each group 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! Step 1: Get Your Bomb Each group of students will attempt to defuse their own personalized bomb. Each bomb is a Linux binary executable file that has been compiled from a C program. To obtain your group’s bomb, one (and only one) of the group members should point your Web browser to the bomb request daemon at http://cs2400.cs.colorado.edu:15213 Fill out the HTML form with the email addresses and names of your team members, and then submit the form by clicking the “Submit” button. The request daemon will build your bomb and return it immediately to your browser in a tar file called bombk.tar, where k is the unique number of your bomb. Save the bombk.tar file to a (protected) directory in which you plan to do your work. Then give the command: tar xvf bombk.tar. This will create a directory called ./bombk with the following files: • README: Identifies the bomb and its owners. • bomb: The executable binary bomb. • bomb.c: Source file with the bomb’s main routine. 1
If you change groups, simply request another bomb and we’ll sort out the duplicate assignments later on when we grade the lab. Also, if you make any kind of mistake requesting a bomb (such as neglecting to save it or typing the wrong group members), simply request another bomb. Step…