Lab 01 - Introduction

• Simple CTF tasks
• Introduction to Python scripting
• Introduction to basic security-related tools

• man
• find
• base64
• hexedit
• Binwalk
• john, zip2john
• xxd
• gzip, bzip2, tar
• CyberChef

You may use the UPB's OpenStack cloud to spawn a Virtual Machine to be used for this lab! Read this guide.

Download the task archive for this section. Each exercise will have a corresponding folder.

• One of your friends gave you this string which looks encoded… Figure out what encoding was used and decode it. Be patient, it may take a couple of decoding rounds :)

• The archive contains the flag. What is the password?
  • Hint: the password is in the wordlist

• The flag for this exercise is found in a file under the inhere directory. The file has the following properties:
  • human-readable
  • 987 bytes in size
  • not executable

• We've found this file on a confiscated machine, but we can't figure what it is. Can you help us?

• During a transmission, one of our files got corrupted. Take a look and see if you can do something about it.

Maybe there is something wrong with the header.

• Hint: use a hex editor to check the file's header

• There is something wrong with the size of this image. Is there anything else there?
  • Hint: use Binwalk. ”-e” option is buggy sometimes.

• We stared at this gif for the last hour but nothing is happening. Would you like to join us and stare at it for the next hour?

• You are being given a file which is a hexdump of the flag that has been repeatedly compressed. Reverse the process and get the flag :)
  • Hint: hexdump, man

• Start this task by opening a specific docker container on your VM:

  docker run -d -p 8080:80 ghcr.io/cs-pub-ro/isc-lab-intro-web

• You can now access a webserver on local port 8080 (try it with curl localhost:8080). Your task is to retrieve the hidden flag by trying all web paths inside the given wordlist (write your own fuzzer in Python, check the lab archive for resources!).
  • Hint: use the Python requests library to issue web requests! Check their HTTP status code to know when you successfully found an existing web file ;)