Buffer Overflow

The package below is the whole lab. The graded handout, the worksheet you submit, the vulnerable source, and the container that builds it are all inside it; this page exists so the lab can be found and cited the same way as every other lab in the course.

What you do

You overflow a stack buffer in a small program and redirect its return address into a win() function. That technique is called ret2win. You then rebuild the same program with each modern defense switched on, one at a time, and write down which defenses stop the attack and which do not. The last section asks you to fix the bug in the source.

What is in the package

• Buffer Overflow.pdf — the graded handout, including the troubleshooting section.
• Buffer Overflow - Student Worksheet.docx — what you fill in and submit.
• lab/Dockerfile — the identical environment for everyone.
• lab/src/ — vuln.c, the corrected vuln_fixed.c, the win() stub, and the Makefile that builds the baseline and every mitigation branch.
• lab/solve.example.py — an exploit scaffold with the blanks left for you.
• lab/hints/ — four hint files. Open them freely, in order, with no penalty.
• lab/lab-doctor.sh — the environment check to run first.

Getting started

docker build -t cybr358-bof lab/
docker run --rm -it cybr358-bof
/lab/lab-doctor.sh

If every line of the environment check reads [ok], you are ready. If not, fix the failing checks before you start; the handout explains each one. On an Apple Silicon Mac the debugger may not work under emulation — the handout describes the x86-64 virtual machine route instead.

Submitting

Your completed worksheet, your payload.bin, your solve script, and your evidence, exactly as the handout describes. A correctly reported result earns the points; an invented result earns zero.

Scope

Everything you attack lives inside the container that ships with this lab. Do not point any of it at a machine you do not own.