Warmup Challenges 2020

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Warmup Challenges 2019

General

Common built-in Linux tools:

• chmod +x <filename>

  Makes a file runnable - chmod changes permissions of a file.

• ./<filename>

  Run a file.

• file <filename>

  View file type and information.

• strings <filename>

  Print all printable strings in a file.

• nc <host> <port>

  Use netcat to connect to a remote host. This is very common in the pwn category and other remote challenges.

• xxd <filename>

  View the hex dump of a file using xxd.

• base64 -d <filename>

  Decode a Base64-encoded file.

Web

• Browser developer tools

  Found in most browsers by pressing [F12].
  Here you can view the network traffic, cookies, page source code and more.

• robots.txt

  Most web pages has this file, located at www.example.com/robots.txt. This is to prevent web crawlers from traversing certain places of a web page.
  Hidden paths and information may be found here.

Binary

Some common disassembly and debugging tools:

• gdb

  The Gnu debugger, built into most Linux systems.

• OllyDbg

• IDA Pro

• radare2

• ghidra

Scripting

Sometimes you have to write short scripts to solve certain challenges.
We recommend using your favourite language.

Common languages include:

• Python

• C/C++

• bash

• perl

• ruby

• PHP

It is strongly recommended to learn how to script over a TCP connection.
You can do this how you like, but pwntools makes this as easy as ABC:
#!/usr/bin/python2
# This is just an example...
from pwn import *
io = remote(host='127.0.0.1', port=1337)
io.recvline() # Receive a line of text
payload = "AAAAAAAAAA"+shellcode
io.sendlineafter(": ", payload) # Combination of recvuntil(delimiter) and sendline()