Overview

libctfso-overthetop is a bundle of ARM Linux CTF challenges requiring memory corruption.

Works out of the box on my machine, YMMV - PR's welcome.

Prerequisites

To use this bundle you should have Vagrant installed along with one of the following hypervisors:

• Virtualbox
• Hyper-V
• Parallels
• libvirt+QEMU
• VMWare Desktop (should work but not tested)

If you know what you're doing and prefer to manage deployment yourself, you can simply run the Ansible playbook on a Ubuntu Xenial amd64 target.

Notes

If you are using Parallels or libvirt+QEMU, please ensure you have rsync installed locally.

If this is your first time using Vagrant with libvirt, please run vagrant plugin install vagrant-libvirt.

If this is your first time using Vagrant with Parallels, please run vagrant plugin install vagrant-parallels.

If this is your first time using Vagrant with Hyper-V, please run all commands from an Administrator console. In addition, you will be asked to enter your Windows username/password to enable shared folder support for provisioning.

Usage

The following command will download a Ubuntu 16.04 VM template from VagrantHub, create a new virtual machine for 'libctfso-overthetop', and build/install challenges under the /challenges directory of the VM:

Note: This can take a while the first time you run it depending on your host specs and internet connection.

vagrant up

You can re-provision anytime with:

vagrant provision

You can connect to the virtual machine with:

vagrant ssh

This will login to the virtual machine using the 'vagrant' user account, which has sudo privileges so that you can install any additional packages that you want.

You can stop the virtual machine with:

vagrant halt

And delete the virtual machine with:

vagrant destroy

Challenges

You should switch to the 'hahn' user account (password = 'hahn') when you are ready to play:

su - hahn

All challenges can be found under the /challenges/ directory.

Difficulty estimates are relative to other challenges in this bundle.

---

Title: softcover-walk
Category: ARM Memory Corruption
Flag: libctf{8d26bc70-5d8f-423d-8e8b-afce769344d1}
Relative Difficulty: Easy

---

Title: bashes-sp-data
Category: ARM Memory Corruption
Flag: libctf{7b86c8cb-70a9-43d5-8642-2ab65ce18a46}
Relative Difficulty: Medium

---

Title: fat-morphine
Category: ARM Memory Corruption
Flag: libctf{14b9c051-4a0a-4158-a303-b85a181bac96}
Relative Difficulty: Medium

---

Title: whoever-flopa
Category: ARM Memory Corruption
Flag: libctf{8eb6767f-9440-44da-9c3a-57cb210f441e}
Relative Difficulty: Hard

---

Hints

Each challenge directory should have everything you need to figure out a plan of attack. If you really want, you can treat this source repository as an oracle by asking it questions like:

hahn@apocalypse:~/libctfso-overthetop/ansible/roles$ grep -iR 'randomize_va_space' . >/dev/null && true || false
hahn@apocalypse:~/libctfso-overthetop/ansible/roles$ echo $?
0
hahn@apocalypse:~/libctfso-overthetop/ansible/roles$ grep -iR 'idontexist' . >/dev/null && true || false
hahn@apocalypse:~/libctfso-overthetop/ansible/roles$ echo $?
1
hahn@apocalypse:~/libctfso-overthetop/ansible/roles$