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Modern Binary Exploitation - CSCI 4968

This repository contains the materials as developed and used by RPISEC to teach Modern Binary Exploitation at Rensselaer Polytechnic Institute in Spring 2015. This was a university course developed and run solely by students to teach skills in vulnerability research, reverse engineering, and binary exploitation.

About the Course

Vulnerability research & exploit development is something totally outside the bounds of what you see in a normal computer science curriculum, but central to a lot of what we RPISEC members find ourselves doing in our free time. We also find that subjects in offensive security tend to have a stigma around them in university that we would like to help shake off. These are practical, applied skills that we're excited to share with those interested in learning.

The question this course posed was 'Can we teach a bunch of programmers how to pwn?'

Course website: http://security.cs.rpi.edu/courses/binexp-spring2015/

Syllabus: http://security.cs.rpi.edu/courses/binexp-spring2015/Syllabus.pdf

Course Abstract

Cybersecurity is one of the fastest growing fields in computer science, though its study is rarely covered in academia due to its rapid pace of development and its technical specificity. Modern Binary Exploitation will focus on teaching practical offensive security skills in binary exploitation and reverse engineering. Through a combination of interactive lectures, hands on labs, and guest speakers from industry, the course will offer students a rare opportunity to explore some of the most technically involved and fascinating subjects in the rapidly evolving field of security.

The course will start off by covering basic x86 reverse engineering, vulnerability analysis, and classical forms of Linux-based userland binary exploitation. It will then transition into protections found on modern systems (Canaries, DEP, ASLR, RELRO, Fortify Source, etc) and the techniques used to defeat them. Time permitting, the course will also cover other subjects in exploitation including kernel-land and Windows based exploitation.

Prerequisite Knowledge

This course carried a prereq of Computer Organization - CSCI 2500 at RPI. Computer Organization is RPI's basic computer architecture course that teaches things like C, MIPS assembly, x86 assembly, Datapaths, CPU Pipelining, CPU Caching, Memory Mapping, etc.

Our expected demographic for Modern Binary Exploitation was students with zero reverse engineering or binary exploitation knowledge. That said, to be able to take this course you will probably need at least the following skills.

Working knowledge of C/C++
Any assembly level experience
Basic Linux command line experience

Lecture Breakdown

Lecture	Title	Topics
01	Syllabus and Review	Linux, C, x86
02	Introduction to Reverse Engineering	Tools and the VM
03	Extended Reverse Engineering	GDB & IDA
04	Intro to Memory Corruption	ELF, the stack, calling conventions, buffer overflows
05	Shellcoding / Code Injection	Writing shellcode, developing scenario relevant payloads
06	Format String Vulnerabilities	Format strings, DTOR/GOT overwrites
07	DEP and ROP	Data Execution Prevention, writing ROP chains, ret2libc
08	Secure Systems and Game Console Exploitation	OpenBSD, SELinux, GRSEC, Game Console Exploitation
09	Address Space Layout Randomization (ASLR)	Overview, info leaks, partial overwrites, ASLR closure
10	Heap Exploitation	Heap structure and concepts, corruption, use after free
11	Misc Concepts and Stack Cookies	Signed/unsignedness issues, uninitialized data, etc, bypassing stack cookies
12	C++ Differences and Concepts	C++ basics, structures, vTables, exceptions
13	Linux Kernel Exploitation	Kernel basics, kernel exploitation, mitigations (mmap_min_addr, kallsyms, SMEP/SMAP), bypassing mitigations
14	Exploitation on 64bit, ARM, Windows	Exploitation differences on other architectures & platforms
15	Automation & The Future of Exploitation	Fuzzing, taint analysis, dynamic instrumentation, SMT/SAT solvers

Refer to ERRATA.md for slide corrections.

Lab Breakdown

Lab	Topic	Corresponding Lectures
01	Reverse Engineering	01-03
02	Memory Corruption	04
03	Shellcoding	05
04	Format Strings	06
P1	Project 1	01-06 (Comprehensive)
05	DEP and ROP	07
XX	ASLR should always be enabled from this point on	See VM Information for details
06	ASLR	09
07	Heap	10
08	Misc and Stack Cookies	11
09	C++	12
P2	Project 2	01-12 (Comprehensive)
10	Linux Kernel	13

Repository Breakdown

src/ - Source code for labs
setup_wargame.sh,external_tools.sh - Install scripts to setup MBE on an Ubuntu 14.04 32-bit machine
MBE_release.tar.gz - Binaries for labs and projects
MBE_lectures.tar.gz - PDFs of all lecture slides
MBE_VM.vmdk.gz - A vmdk (disk image) of a VM that is already setup

Labs - The RPISEC Warzone

The Warzone is a custom wargame that was built from the ground up for this course. It provided a complete and consistent learning platform for us to release the labs and projects to the students. The wargame was built ontop of a vanilla Ubuntu 14.04 32-bit server install, and is modeled after existing local privilege escalation themed wargames. If you have ever played the fantastic IO wargame (formerly hosted at SmashTheStack), the Warzone has a somewhat similar structure.

Some basic tweaks have been made in an attempt to isolate players from each other and create an individual experience, but it's probably far from perfect. It also comes pre-installed with some tools, scripts, and configs that can make a beginner's life a bit easier in exploit development.

You can roll with the Warzone we designed, or you can try to setup your own using our scripts.

Option One - Pre-made Warzone VM

As the years pass, compilers will change, security will improve, and the challenges in this repo may no longer be solvable. Because of this, we have created a virtual machine disk image that closely replicates the universal Warzone wargame server we ran for the duration of this course. The VM has all the tools setup, challenges pre-compiled, and lab accounts ready to go. Hopefully it will endure the test of time.

Virtual Machine Setup

RPISEC is a huge advocate of VMware because of its quality and stability, so we recommend using our disk image below with VMware Workstation, VMware Fusion, or VMware Player. That said, it should also work with VirtualBox.

VMware provides a great 2 minute video on how to setup a virtual machine using an existing disk image.

Download MBE_VM.vmdk.gz from our release page
Extract the archive to obtain the disk image
Using VMware go to File->New Virtual Machine... and create a Custom VM
When prompted for Guest Operating System Installation, select I will install the operating system later
You can use the default options for almost all the prompts you encounter. For specs, we suggest the following:

1 processor / core
512 MB of RAM
NAT Networking

When prompted to Select a Disk, select Use an existing virtual disk and navigate to the .vmdk you extracted
In the end your final screen should look something like this. Click Finish and then power on the VM.

How to Play

We tried to keep the course fairly self contained but if you find yourself lost or struggling OverTheWire's Bandit is a great intro to Linux wargames. You can also poke people on IRC if you have questions.

SSH is pre-setup on the VM, but we need an IP. First, sign in through the VMWare or VirtualBox console. To find the IP address type: $ ip addr <img src="/resources/images/ip_addr.png" alt="ip addr"/> and then SSH using [PuTTY](http://the.earth.li/~sgtatham/putty/latest/x86/putty.exe) or a command line client <code>$ ssh lab1C@172.16.29.130</code> <code>lab1C@172.16.130's password: lab01start</code>
Navigate to /levels/labXX to begin $ cd /levels/lab01
The Warzone is structured like any local privilege escalation wargame. You must exploit a challenge to escalate your privileges and gain access to another user (level). Once you exploit a level and escalate to the next user (confirm with whoami), read their password from their home dir $ cat /home/lab1B/.pass
SSH in using the new username and password to continue!

VM information

admin user: gameadmin:gameadmin
lecture user: lecture:lecture
rc files are in /etc/cfg
- All lab/project users have symlinks to these files in their home directories
- These files are also symlinked in /etc/skel
To begin a lab, login as labXC:lab0Xstart
- e.g. lab1C:lab01start
- Projects are projectX:projectXstart
Levels are in /levels
Passwords are in /home/$USER/.pass
Tools are installed in /tools and /usr/local/bin
ASLR must be enabled after completing the DEP/ROP lab, and stay enabled for the rest of the course
- Until reboot: # echo 2 > /proc/sys/kernel/randomize_va_space
- Persist reboot: # echo 'kernel.randomize_va_space = 2' > /etc/sysctl.d/01-disable-aslr.conf

Option Two - Make a Custom Warzone

We have provided a bash script that will fully setup the exact environment in the provided VM.

DO NOT RUN THIS SCRIPT ON YOUR PERSONAL COMPUTER, RUN IT IN A VIRTUAL MACHINE

Download MBE_release.tar.gz
Move the archive to your VM or machine and extract it NOTE: It is not recommended to run the script from /tmp, as the sticky bits can screw up wildcards $ tar xzvf MBE_release.tar.gz
Modify the configuration variables at the top of setup_wargame.sh to suit your needs
Make the setup script executable and run it with sudo $ chmod +x ./setup_wargame.sh $ sudo ./setup_wargame.sh It should take about 10-20 minutes to complete depending on your internet connection and the number of Ubuntu updates.

Frequently Asked Questions

Why can't I login to lab1c?

Account names are case sensitive, so please check that you're logging in as lab1C

Why am I getting 'permission denied' errors?

The warzone marks many files as immutable to prevent users from changing them and ruining the game for other players. For example, we don't want the lab2B user to delete its .pass file or /levels files. A few system files, such as /etc/passwd, are also marked immutable.

If you would like to modify or delete these files simply remove the immutable flag

chattr -i filename

We recommend that you add the flag back when you are done making your changes

chattr +i filename

Where are the lab solutions?

Posting solutions spoils the fun and grind of the game, and as an academic resource it is likely some of these materials may be re-used by other classes in the future. As goes with most wargames, we would like to ask that you refrain from publicly posting writeups or exploits to the labs and projects.

If you are ever stuck on a problem or have any questions, you're more than welcome to ask on IRC.

Why are the lecture slides for XYZ so sparse?

This was a very hands on course, so almost every lecture we had students slinging GDB commands or following along with us on screen. The slides were accessory to the lectures and may have gaps or experience brevity at times. With seven of us creating and giving lectures, the slides and teaching styles vary a bit. We did our best to keep them consistent.

Do you have videos of the lectures?

Sadly we did not record any of the lectures, maybe next time.

Why provide the lab sources to the students?

We're huge fans of reversing / CTF challenges, but reversing is mostly a time problem. With students juggling other classes and work during the school semester, we'd rather them focus on learning the exploitation techniques without the overhead of reversing every binary.

These challenges are really easy, what gives?

The 50 students that enrolled had little to no prior computer security experience. The labs are not designed to be novel CTF challenges, they're meant to be more academic examples paced to crystallize the concepts. Seasoned CTF'ers can probably blow through most of these challenges in a day or two.

Why didn't you cover subject XYZ?

If XYZ is related to vulnerability research, we're all ears. The course is far from perfect and we are open to hear any feedback for improving it.

Will this course be taught again at RPI?

There's a lot of interest in having it offered again, so it's being considered for Spring 2016. The feedback was almost exclusively positive with the students finding the material challenging, but engaging. We've got dozens of ideas on how to make it even better next time.

Where can I learn more?

Play more wargames:

And when they're happening, play CTFs!

<a name="contact"></a>I have a question, how can I get in touch with you?

Our club keeps a pretty active IRC presence. Someone there can probably answer your question.

Server: irc.rpis.ec Port: 6667, or 6697 (SSL)

If you would like a more formal means of communication, you can reach us at contact [at] rpis.ec

Licensing

This course was explicitly designed for academic & educational use only. Please keep this in mind when sharing and distributing our course material. The specific licenses involved can be found below.

Lecture Slides

The lectures are covered by the Creative Commons Attribution-NonCommercial 4.0 International license CC BY-NC 4.0.

Code

The code in this repo is covered by the BSD 2-Clause license. You can view this license in LICENSE.

Acknowledgements

Hundreds of hours and countless all nighters went into the production and execution of this course. This section serves to recognize those who made all of this possible.

Original Authors

Patrick Biernat
Jeremy Blackthorne
Alexei Bulazel
Branden Clark
Sophia D'Antoine
Markus Gaasedelen
Austin Ralls

Special Thanks

The RPI CS Department for giving us this opportunity and letting us run with it
Professor Bülent Yener for sponsoring such a course
Our students who put up with us all semester