You Can't See Me - Forensics - Cyber Siege 23

Hint: https://www.youtube.com/watch?v=2ctD30NNiEo

https://www.youtube.com/watch?v=2ctD30NNiEo&ab_channel=MEMES69

Solution:

The user is given a file named you_cant_see_me.jpg

Well, the image is of Louis Braille. Pretty simple to know if you know how to Reverse Search on Google Images.

Also, we check the strings of the image to see if we find anything useful. You can use HxD on Windows or strings on Linux. We are greeted with a ton of garbage values. So finding something useful is probably like a needle in haystack.

Notice that at the end of the file, some random 1’s and 0’s are given. Seems like something useful. Moreover, moving slightly above the last lines, we find ourselves a note. It seems like the given note is about how to decrypt the flag.

QU9G{110000111000010100101110100110_101100100000101110_100100100000101110_010110101001100110110110100010_101110101010_100100101010111000101010111010011100}

Notice how at the very start we got to know that the given image was of Louis Braille who designed the Braille language.

Braille is a system of raised dots that can be felt with the fingertips and used to represent letters, numbers, punctuation, and other symbols. It was invented by Louis Braille, a Frenchman who was blind, in 1824. The Braille system uses a grid of 6 dots, with each dot being either raised or not raised, to represent a character. Each character is made up of a unique combination of raised dots within the grid and can be recognized by a person's sense of touch.

This is how Braille works

The note tells us to move down the left column first. We can simply decrypt the flag by matching each bold dot to 1 and the other to 0 to find the flag.

You can decode using this C++ code as well:

#include <iostream>
#include <unordered_map>
using namespace std;

unordered_map<string, char> braille_map = {
    {"000000", ' '},
    {"100000", 'a'},
    {"110000", 'b'},
    {"100100", 'c'},
    {"100110", 'd'},
    {"100010", 'e'},
    {"110100", 'f'},
    {"110110", 'g'},
    {"110010", 'h'},
    {"010100", 'i'},
    {"010110", 'j'},
    {"101000", 'k'},
    {"111000", 'l'},
    {"101100", 'm'},
    {"101110", 'n'},
    {"101010", 'o'},
    {"111100", 'p'},
    {"111110", 'q'},
    {"111010", 'r'},
    {"011100", 's'},
    {"011110", 't'},
    {"101001", 'u'},
    {"111001", 'v'},
    {"010111", 'w'},
    {"101011", 'x'},
    {"101111", 'y'},
    {"101101", 'z'}};

string braille_to_text(const string &braille)
{
    string result;
    for (int i = 0; i < braille.size(); i += 6)
    {
        string braille_cell = braille.substr(i, 6);
        if (braille_map.count(braille_cell))
        {
            result += braille_map[braille_cell];
        }
        else
        {
            result += "?";
        }
    }
    return result;
}

int main()
{
    string braille = "INSERT ENCODED TEXT HERE";
    cout << braille_to_text(braille) << endl;
    return 0;
}

Or use dcode.org to find Braille Decoder:

So we have our first part:

blind_man_can_judge_no_colors

To find the first part, simply decode using Base64 and you will find AOF

So the final flag becomes:

AOF{blind_man_can_judge_no_colors}