HackTheBox Shattered Tablet Writeup

Explore the basics of cybersecurity in the Shattered Tablet Challenge on Hack The Box. This very-easy-level Challenge introduces encryption reversal and file handling concepts in a clear and accessible way, perfect for beginners.

I decompiled the program using Ghidra and created a buildable version. The main function checks each character in the array, enabling us to sort the characters and uncover the expected string.

#include <stdio.h>
#include <string.h>

int main(void) {
    char input[64] = {0};
    printf("Hmmmm... I think the tablet says: ");
    fgets(input, sizeof(input), stdin);
    input[strcspn(input, "\n")] = 0;
    if (
        (input[34] == '4') && (input[20] == '3') && (input[36] == 'r') &&
        (input[1]  == 'T') && (input[21] == 'v') && (input[6]  == '0') &&
        (input[39] == '}') && (input[38] == 'd') && (input[31] == 'r') &&
        (input[29] == '3') && (input[8]  == '3') && (input[22] == 'e') &&
        (input[35] == '1') && (input[5]  == 'r') && (input[0]  == 'H') &&
        (input[32] == '3') && (input[18] == '.') && (input[13] == '4') &&
        (input[3]  == '{') && (input[10] == '_') && (input[16] == '.') &&
        (input[4]  == 'b') && (input[7]  == 'k') && (input[15] == 't') &&
        (input[14] == 'r') && (input[19] == 'n') && (input[25] == 't') &&
        (input[17] == '.') && (input[9]  == 'n') && (input[30] == '_') &&
        (input[26] == '0') && (input[24] == '_') && (input[12] == 'p') &&
        (input[23] == 'r') && (input[28] == 'b') && (input[33] == 'p') &&
        (input[2]  == 'B') && (input[27] == '_') && (input[11] == '4') &&
        (input[37] == '3')
    ) {
        puts("Yes! That's right!");
    } else {
        puts("No... not that");
    }
    return 0;
}

The code to print the flag is as follows:

#include <stdio.h>
#include <string.h>

typedef struct {
    int index;
    char expected_char;
} Check;

int main(void) {
    char flag[41] = {0};
    Check checks[] = {
        {0, 'H'}, {1, 'T'}, {2, 'B'}, {3, '{'}, {4, 'b'}, {5, 'r'}, {6, '0'}, {7, 'k'},
        {8, '3'}, {9, 'n'}, {10, '_'}, {11, '4'}, {12, 'p'}, {13, '4'}, {14, 'r'}, {15, 't'},
        {16, '.'}, {17, '.'}, {18, '.'}, {19, 'n'}, {20, '3'}, {21, 'v'}, {22, 'e'}, {23, 'r'},
        {24, '_'}, {25, 't'}, {26, '0'}, {27, '_'}, {28, 'b'}, {29, '3'}, {30, '_'}, {31, 'r'},
        {32, '3'}, {33, 'p'}, {34, '4'}, {35, '1'}, {36, 'r'}, {37, '3'}, {38, 'd'}, {39, '}'}
    };
    int num_checks = sizeof(checks) / sizeof(Check);
    for (int i = 0; i < num_checks; i++) {
        flag[checks[i].index] = checks[i].expected_char;
    }
    flag[num_checks] = '\0';
    printf("The flag is: %s\n", flag);
    return 0;
}

gcc main.c && ./a.out