Assignment 1 A simple backdoor program.

Assignment 1

Weight: 10% of your final grade.

In this assignment you are going to implement a simple backdoor program. You can write your program
in C, C++ or Python. Your backdoor must be able to run on the Linux machines in the computer labs.
When your backdoor program starts, it will simply listen on some port for a client to connect. When the
client connects, it should perform some very simple hand-shake mechanism, e.g. by accepting a
hard-coded password. After the handshake is successfully finished, the server will start accepting
commands from the client, execute them and return results. When a client disconnects, the backdoor
resumes waiting for a new connection. If the handshake is unsuccessful, i.e. the first command sent is
not correct, the backdoor will either drop the connection, or simply do nothing from then on.
Your backdoor should be usable by connecting to it using netcat. That means you do not need to write a
client program for this assignment. Also, your backdoor program only needs to service one client at a
time. There is no need to support multiple simultaneous clients.
At minimum, your backdoor must be able to understand the following commands:
Command Description
pwd returns current working directory
cd <dir changes current working directory to <dir
ls lists the contents of the current working directory
cat <file returns contents of the file
help prints a list of commands
off terminates the backdoor program
On top of the required commands, you must implement at least two additional commands of your own
choice. You can be creative with these. Here are some suggestions:
Command Description
who list user[s] currently logged in
net show current networking configuration
ps show currently running processes
nmap <params run nmap with parameters <params
ext <program <params run program <program with parameters <params
Group work:
Although this is a very simple assignment, and it was designed to be easily completed by a single
person, you are allowed to work on it with another student (max. group size is 2). Just beware that
during the demo you will be asked to demonstrate your familiarity with all of the code. So if you do
decide to group up, both of you should understand the code 100%.
Demo [90/100 points]
You are required to demo your assignments individually. During the demo you will be asked to run the
backdoor program on one computer, and access the backdoor from another computer. Then you will be
asked to demonstrate the functionality of your backdoor. You might be asked to adjust some
functionality of the backdoor program to illustrate you are familiar with the internals of the
implementation. The time for your demo will be arranged by your TAs.
Submissions [10/100 points]
Submit your code via D2L. If you decide to work in a group, each group member needs to submit the
assignment. With your code you should submit a document (text or pdf) that includes: your name, ID and
tutorial section, as well as the name of your partner (if applicable). The document should also include
brief description of the functionality of your backdoor:
● how to run it;
● how to connect to it, including handshake details;
● supported commands.
Sample session:
$ nc 136.159.5.122 9312
pass p@ssw0rD
welcome boss
help
ls ls cwd
cd change cwd
pwd print cwd
cat cat a file
off kill me
ps print process table
net ifconfig
cd /usr
OK
ls
drwxr-xr-x. 3 root root 4096 Apr 19 2016 abrt
-rw-r--r--. 1 root root 18 Aug 17 2015 adjtime
-rw-r--r--. 1 root root 1518 Feb 23 2015 aliases
-rw-r-----. 1 root smmsp 12288 Apr 19 2016 aliases.db
drwxr-xr-x. 2 root root 4096 Aug 17 2015 alsa
…
cat passwd
root:x:0:0:Mr. Rooter Fedora Workstation,,,:/root:/usr/bin/tcsh
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
off
I hate you.
General information about all assignments:
1. Due time: All assignments are due at 23:59 on the due date listed on the assignment. Late
assignments or components of assignments will not be accepted for marking without approval
for an extension beforehand. What you have submitted in D2L as of the due date is what will be
marked.
2. Extensions may be granted for reasonable cases, but only by the course instructor, and only
with the receipt of the appropriate documentation (e.g., a doctor's note). Typical examples of
reasonable cases for an extension include: illness or a death in the family. Cases where
extensions will not be granted include situations that are typical of student life, such as having
multiple due dates, work commitments, etc. Forgetting to hand in your assignment on time is not
a valid reason for getting an extension.
3. After you submit your work to D2L, make sure that you check the content of your submission.
It's your responsibility to do this, so make sure that your submit your assignment with enough
time before it is due so that you can double-check your upload, and possibly re-upload the
assignment.
4. All assignments should include contact information, including full name, student ID and tutorial
section, at the very top of each file submitted.