x0nu11byt3

Keybase proof

I hereby claim:

I am x0nu11byt3 on github.
I am x0nu11byt3 (https://keybase.io/x0nu11byt3) on keybase.
I have a public key whose fingerprint is 3611 378E 9F55 2535 7C14 C28E 7FB2 0695 50E8 9AF0

To claim this, I am signing this object:

Advent Calendar CTF 2014

Aditional note: This is a translated version of the original project gist.github.com/st98/memo.md

We participated as Bok Team omakase. The final score was 173 points and the team was ranked 24th (out of 505 teams). We solved the problems on days 1 to 14, 21 to 22 and 25.

1 warmup (misc)

'0x41444354465f57334c43304d335f37305f414443374632303134'.match(/[0-9a-f]{2}/g).map(function(c){return String.fromCharCode(parseInt(c, 16))}).join('');

ELF Format Cheatsheet

Introduction

Executable and Linkable Format (ELF), is the default binary format on Linux-based systems.

Compilation

I played Harekaze Mini CTF 2020 for about 3 hours this weekend. The pwn challenges were nice (I especially enjoyed nm-game-extreme). Here are some short writeups.

shellcode

The program just tells you to provide shellcode that will execute execve("/bin/sh", NULL, NULL). It gives you the address of the "/bin/sh" string, so you just create shellcode to do the job and send it:

#!/usr/bin/env python3

from pwn import *

	#include <stdio.h>
	#include <stdlib.h>

	int main ( int argc, char** argvs ) {
	int a = -127;
	int b = 4;
	int mod_ = a % b;
	int mod_alt_a = a - b * ( a / b );
	// mod_alt works as alternative to modulo
	int mod_alt = a & ( b - 1 );

	from z3 import *
	import struct

	# calculate e,f,d for a given input password
	def calc(m):
	e = 0
	f = 0
	d = 0
	for i in xrange(0, len(m)):
	c = ord(m[i])

	#include <stdio.h>
	#include <stdlib.h>
	#define MAX_SIZE 50

	typedef struct {
	int key;
	char name[MAX_SIZE];
	char departament[MAX_SIZE];
	char category[MAX_SIZE];
	float antiquity;

	#!/usr/bin/env python3

	import os
	import sys
	import paramiko

	class SSHClient:

	def __init__(self,hostname, port, username, password):
	self._port = port

	#!/usr/bin/env python3

	import numpy as np
	class error(Exception): pass

	class GaussJordan():
	def __init__(self,x,y):
	self.m = x
	self.n = y
	self.matrix = [[ 0 for i in range(x)] for j in range(y)]

	This is a collection of NFO templates from various PSP Crack / Warez Groups

	--- 4Fun

	▄▀ ▄▄█▓▄ ____________________ __________ ▄▓█▄▄ ▀▄
	▐█ ███▀██▓▄ / \| \_ _____/ \| \ \@TiLK ▄▓██▀███ █▌
	▓██▀ ░▐█▓▓ / \| \|\| __) \| \| / \| \ ▓▓█▌░ ▀██▓
	▀█▓ ░▐█▓▌ / ^ / \ \| \| / \| \ ▐▓█▌░ ▓█▀
	▀▀ ▄██▓ \____ \|\___ / \|______/\____\|__ / ▓██▄ ▀▀
	▄██▓▀ ▄▀ \|__\| \/ \/ ▀▄ ▀▓██▄