komen205

var hexToAscii = function(input){
    var hex = input.toString();
    var str = '';
    for (var i = 0; i < hex.length; i += 2)
      str += String.fromCharCode(parseInt(hex.substr(i, 2), 16));
    return str;
  }
  

komen205

```
Create removed.txt file
5F 39
33 5F 
F8 99 
53 34 
F8 83 
9A F7 
DD EE 
5C 6F 

komen205

emoji hunt:
flag{emojis_more_like_free_cloud_storage}
step 1. Copy all images https://squarectf.slack.com/customize/emoji?utm_source=in-prod&utm_medium=inprod-customize_link-slack_menu-click
step 2. follow https://gist.github.com/tobek/a17fa9101d7e28ddad26
step 3. use tab save and download all images
step 4. and you get the flag exiftool . | grep -i "fl "
Fl 1                            : ag
Fl 1                            : ag
Fl 7                            : re
Fl 7                            : re

komen205

By connecting to the server we see that it requires one or more inputs, when the input is something like 1 then 1. We encounter a door which requires a password. Now we can look at the binary file.

I used Ghidra to decompile the file at first, then only later used IDA. First, by looking at the strings we can see some strings that we saw on the server output.	I traced them back and found this method.

https://imgur.com/AijEsVe

It is interesting that the function call has an unusual name “fnv_1a_32”. If we search this on google the first search is a wikipedia page “Fowler–Noll–Vo hash function”.

https://imgur.com/NYkjCRm

komen205

#!/usr/bin/env python
# -*- coding: utf-8 -*-

# Brute-force string generation
# Copyright (C) 2011 Radek Pazdera

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.