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  1. Brain

    We are presented a string in brainfuck language. The first thing we notice that it is not outputting anything (not a single '.' character in it).

    >+++++++++++[<++++++++++>-]<[-]>++++++++[<++++++>-]<[-]>++++++++[<++++++>-]<[-]
>++++++++++++++[<+++++++>-]<[-]>+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++[<++>-]<[-]
>+++++++++++++++++++++++++++++++++++++++++[<+++>-]<[-]>+++++++[<+++++++>-]<[-]
>+++++++++++++++++++[<+++++>-]<[-]>+++++++++++[<+++++++++>-]<[-]>+++++++++++++[<++++>-]<[-]
>+++++++++++[<++++++++++>-]<[-]>+++++++++++++++++++[<+++++>-]<[-]>+++++++++++[<+++++++++>-]<[-]
>++++++++[<++++++>-]<[-]>++++++++++[<++++++++++>-]<[-]>+++++++++++++++++[<+++>-]<[-]
>+++++++++++++++++++[<+++++>-]<[-]>+++++++[<+++++++>-]<[-]>+++++++++++[<++++++++++>-]<[-]
>+++++++++++++++++++[<+++++>-]<[-]>++++++++++++++[<+++++++>-]<[-]
>+++++++++++++++++++[<++++++>-]<[-]>+++++++++++++[<++++>-]<[-]>+++++++[<+++++++>-]<[-]
>+++++++++++[<++++++++++>-]<[-]>+++++++++++++++++[<++++++>-]<[-]>+++++++[<++++++>-]<[-]
>+++++++++++[<+++++++++>-]<[-]
>+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++[<+>-]<[-]
>+++++++++++[<+++>-]<[-]>+++++++++++++++++++++++++[<+++++>-]<[-]

    The next thing that jumps into ones eye are these <[-]. The < jumps right back into the previous memory cell while [-] is equal to

    while (cell_value …
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  2. Numbers2

    Numbers2 is the successor of an older challenge presented at N00bzCtf 2023 with a few differences:

    • It outputs and additional welcome message
    • It asks for three different challenge questions
    • successful solving attempts are being answered with different responses

    We have to solve several programming challenges here:

    1. Challenge inputs do not …
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  3. Random

    We are given parts of the cpp source of the challenge. The main functions reads in a line and is doing some checks in the input

        map<char, int> counts;
    for (char c : s) {
        if (counts[c]) {
            cout << "no repeating letters allowed passed this machine" << endl;
            return 1;
        }
        counts[c …
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  4. SillyGoose

    Simple binary search number guessing game. You guess a number and the challenge tells you whether the goal is lower or higher.

    import sys

lower_bound = 1
upper_bound = pow(10, 100)

f = open("sillygoose.log", "w")

found = False
while not found:
    attempt = lower_bound + (upper_bound - lower_bound)//2
    print(str(attempt))
    f.write …
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