Lab 03: Tracing is fun, but gdb is funner!

Submission instructions for labs can be found on the resource pages. In paticular, you should view this subsection: Creating a new branch and submitting

Description

• Given the compiled program main, use gdb to trace and analyze it to find the secret message

preliminaries

• The assignment can be completed on your VM machine
• gitlab repository

http://saddleback.academy.usna.edu/aviv/lab-3.1

Instructions

• fork and clone the repo
• You will find a single file: main
• Use gdb to analyze the file and determine the embeded secret message
• Once found, fill in the json file:

  {
    "msg" : "Secret message",
    "description": "Description of where and how the secret message was found"
  }
  

Submission Requirements

• solution.json

Hint

• You don't need to run the program to find the secret. The computation is not relevant.
• Use the gdb print function to look at extraneous bytes interpreted in different ways

Description

• Crack the decrypted text

preliminaries

• The assignment can be completed on any machine but you must have access to the saddleback VM
• gitlab repository

http://saddleback.academy.usna.edu/aviv/lab-3.2

Instructions

• fork and clone the repo
• You will find one file to complete
  • crack_secret.c : complete the decryption function

• ssh to the saddleback vm:

  ssh -p 2222 saddleback.academy.usna.edu
  

• Execute the following program to get your secret message

  ~aviv/lab/03.2/get_secret
  

  You will get a key and IV, but you need to figure out the encryption routine. Use objdump and gdb to figure that out.

• Once you've cracked the secret, complete the solution.json file:

   {
     "msg": "the secret message"
     "description" : "short description of how you cracked the message",
  }
  

Submission Requirements

• crack_secret.c
• solution.json solution information

Hints

• Because gdb doesn't like setuid, you might have a hard time tracing due to permission issues. But, you can copy the file and try and trace the encryption routine yourself.

Description

• Using gdb and objdump, determine the input that will produce the secret message.

preliminaries

• The assignment can be completed on your VM machine
• gitlab repository:

  http://saddleback.academy.usna.edu/aviv/lab-3.3
  

Instructions

• fork and clone the repo
• You will find one pre-compiled binary file
  • a.out : complete the decryption function
• Using gdb (or objudmp or whatever) determine how to get the binary to print the secret message.
• Once you've cracked the secret, complete the solution.json file:

   {
     "inpput": "input key",
     "msg": "the secret message",
     "description" : "short description of how you cracked the message"
  }
  

Submission Requirements

• solution.json solution information

Hints

• Use gdb to do some tracing of the logic
• To what and from what are the comparisons occurring?