Exercise 1 – pwnexercise

The interesting files here are the two ELF executables hello and pwnexercise.

• hello – ELF executable
• pwnexercise – ELF executable
• hello.c – source code
• hello@.service – server configuration
• hello.socket – server configuration
• pwnexercise@.service – server configuration
• pwnexercise.socket – server configuration
• pwntubes.zip – I/O-only replacement for pwntools if you can’t get it to work

Server configuration files

The other files are just here to satisfy your curiousity if you’re wondering how the server is configured. The services are managed by systemd, which does all sorts of behind-the-scenes stuff on Linux.

The *.service files specify how the programs should be run. Most of the options are used to configure a (hopefully) secure restricted environment.

• See systemd.service(5) and systemd.exec(5)

The *.socket files specify which network ports we should listen to and what service to run when someone connects.

• See systemd.socket(5)

pwntubes

• Download and unzip pwntubes.zip, cd into the directory and run python setup.py install

• Use this code to import the tube functionality:

from pwnlib.tubes.remote import remote
from pwnlib.context import context
context.log_level = 'debug'

io = remote('inf226.puffling.no', 6001)

# …

None of the ELF file stuff will work, but you can at least to the comms stuff. To do the ELF inspection, you can either use objdump directly, or have a look at this printout.