---
title: 'Homework Assignments'
tags: enee459b-fall23
---

## Homework 1. Access
The `access` executable provided in this HW is a piece of software used for granting access to a turnstile. It provides simple user authentication using standard username/password combinations. Unfortunately, the company that developed the software inserted a backdoor to allow unfettered access to all the organizations that use the physical access control system.

* [Download the `access` and `passwd` files](https://yonghwi-kwon.github.io/class/enee459b/data/access.zip)
* `access` is a binary executable file and `passwd` is a text file.
* Obtain the binary in the class VM server

        $ mkdir hw1
        $ cd hw1
        $ wget https://yonghwi-kwon.github.io/class/enee459b/data/access.zip
        $ unzip access.zip
        $ rm access.zip

* [Full Homework Description](https://yonghwi-kwon.github.io/class/enee459b/data/HW1.pdf)

## Homework 2. Data Structures
You have been provided a simple utility (`re-hw2`) that was written by a past co-worker, but nobody is quite sure what it does! It seems to be saving a binary file.
What is it doing, and what format is the binary file in?

* [Download the `re-hw2` binary](https://yonghwi-kwon.github.io/class/enee459b/data/re-hw2)
* Obtain the binary in the class VM server

        $ mkdir hw2
        $ cd hw2
        $ cp /class/re-hw2/* ./

* [Full Homework Description](https://yonghwi-kwon.github.io/class/enee459b/data/HW2.pdf)

## Take home activity: bomb64
The binary is a software bomb that if you could not provide the correct secret input, it will explode. Specifically, the binary has 6 phases where each phase expects a secret input. There is also a secret phase (hence total 7 phases). Can you figure all the expected inputs?
* [**Watch this video for the detailed introduction**](https://umd.instructure.com/courses/1399733/files/folder/Recordings?preview=88279593)
* **Deadlines**
* **Phase 1-3**: March 4th 9:00 am (before the lab).
* **Phase 4-5**: March 11th, 9:00 am (before the lab).
* **Phase 6 and Secret**: March 25th, 9:00 am (before the lab).
* **Note for collaboration/cheating**: All assignmemts (homework, projects, and extra-credit challenges) should be done individually. You can discuss technical details of how to use disassembler, debugger, and decompilers (e.g., ghidra), but you are not allowed to share your answers.
* [Download the `bomb64` binary](https://yonghwi-kwon.github.io/class/enee459b/data/bomb64)
* Download the binary

        $ mkdir bomb64
        $ cd bomb64
        $ wget https://yonghwi-kwon.github.io/class/enee459b/data/bomb64
        $ chmod +x bomb64

* After you download, make sure you download the correct version by checking its `md5sum`. Run `echo "64a13b226de05c074a5a961fe73cf99b bomb64" | md5sum -c -` (including the last `-` after `-c`).

        $ echo "64a13b226de05c074a5a961fe73cf99b bomb64" | md5sum -c -
        bomb64: OK

* If you see `bomb64: OK`, then you are good to go.
* If you see `bomb64: FAILED` and `md5sum: WARNING: 1 computed checksum did NOT match`, you have downloaded a wrong version. If so, please contact me to get the right version.
* [Extra Credit Assignments](https://hackmd.io/@yonghwikwon/SJf9uAWfa)