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100 Reps

Learning goals - Git Gud

 In 3 months there will be a CTF event that I want to attend.

I know absolutely nothing useful for CTF to even compete.

I am not going to be so deluded that I can catch up to their standard and mastery before then to win a placement there.

However, I want to see how I fare with the challenges.

I had a look at HackTheBox, OverTheWire and picoCTF.

picoCTF seems the most friendly so I will start there.

10 years of experience in software development will be an advantage and I can fast track through a lot of basics.

But I will go through the material at 3-4x speed to make sure I cover all bases.

There may be key points in the basics that I miss/forgotten.

Step 1. General Skills

Key Points:

  1. Binary numbers
  2. Encodings
    • Mappings of a number to a meaning
Can you convert the number 42 (base 10) to binary (base 2)?
Doing it manually.

32 16 8 4 2 1
1    0  1 0 1 0

Write the powers of 2 until it hits 42.
Take 42.
Remove the biggest number you see that is a power of 2 (32)
Write down a 1 under 32
Left with 10
Remove the biggest number you see... (8)
Write down a 1 under 8
Left with 2
Remove the biggest number you see... (2)
Write down a 1 under 2
Left with 0
Write zeroes for everything else.

Answer is 101010
Wrap in the flag: picoCTF{101010}

Warmed Up

What is 0x3D (base 16) in decimal (base 10)?
Doing it manually.

3D means 3 x 16 + 13 = 61

Flag: picoCTF{61}

Lets Warm Up

If I told you a word started with 0x70 in hexadecimal, what would it start with in ASCII?

Look it up here: Ascii table

0x70 matches the 'p' lowercase character

Flag: picoCTF{p}


Shells let you type commands to the computer to do operations.
GUIs let you do it graphically.
Got a good bit of experience using this in my work.

Let's do the practice gym questions anyways. (completionism!)
Obedient cat
This file has a flag in plain sight (aka "in-the-clear"). Download flag.
Practice download and read the flag.
Either open with a text editor or use command line

command: cat flag

Flag: picoCTF{s4n1ty_v3r1f13d_1a94e0f9}

Wave a flag
Can you invoke help flags for a tool or binary? This program has extraordinarily helpful information...
Download the file (warm)
Add permission to execute it
chmod +x warm

Run the program ./warm -h
Usually -h will be help file
Run the Python script and convert the given number from decimal to binary to get the flag.
Download file.

what's a net cat?
Using netcat (nc) is going to be pretty important. Can you connect to at port 41120 to get the flag?

nc 41120

You're on your way to becoming the net cat master

Flag: picoCTF{nEtCat_Mast3ry_3214be47}


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