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X-CUBE-CRYPTOLIB (CMOX) and the STM32's CRC unit

This write-up is about the STM32 cryptographic firmware library X-CUBE-CRYPTOLIB, also known as the Cortex-M Optimized Crypto Stack (CMOX). It is a cryptographic library developed by STMicroelectronics (ST) for their series of STM32 processors, which are based on the ARM Cortex-M family.

Hardware features vary across different STM32 processors. Because CRC checksums are widely used in embedded systems, most (if not all) STM32 processors feature a hardware CRC unit that is supposed to accelerate CRC computations.

Introduction

Interestingly, on the page "Getting started with the Cryptographic Library", ST claims:

The cornbread recipe is easy; it's right off the Alber's Yellow Cornmeal box.

1 cup Alber's yellow cornmeal
1 cup all purpose flour
1/4 cup granulated sugar
1 Tbs. baking powder (Not soda)
1 tsp. salt
1 cup milk
1/3 cup vegetable oil (like canola)
1 large egg, slightly beaten

Dumping the flash of the Syscan 2015 badge

The badge of the Syscan 2015 conference included an ARM-based STM32F030R8 processor running some challenges. Although SWD pins are accessible on the badge, some have noted that the STM32 is readout-protected, meaning that it will refuse to dump its flash memory.

Fortunately, two researchers (Johannes Obermaier and Stefan Tatschner) recently published a paper at the WOOT '17 conference, in which they reveal a vulnerability allowing to bypass the readout protection. Their technique allows to dump the flash one DWORD at a time, rebooting the CPU between each access.

I implemented this attack using a BusPirate and the PySWD module. Here is a quick'n dirty PoC to

Tutorial 0

What is Vulkan

Vulkan is a low-overhead, cross-platform 3D graphics and compute API.

Vulkan targets

Vulkan targets high-performance realtime 3D graphics applications such as games and interactive media across multiple platforms providing higher performance and lower CPU usage.

SASL authentication in IRC

This documentation is released under Creative Commons 3.0 Attribution license.

This is a description of server-server protocol, intended for ircd and services developers. For the client-server protocol descriptions, intended for client & bot developers, see the IRCv3 [sasl-3.1][] and [sasl-3.2][] specifications.

Guide to how fucked is SSL?

Thanks to Jacob Kaplan-Moss, Donald Stufft, David Reid, Allen Short, Zain Memon, and Chris Armstrong for review.

This is a guide for technical individuals to understand in what circumstances SSL communications are secure against an observer-in-the-middle (for all intents and purposes: the NSA).

	''' Provides a very basic (read: shitty) FT2232H SWD implementation. '''

	import time
	import logging
	import binascii

	from struct import pack
	from struct import unpack
	from operator import xor
	from pyftdi.gpio import GpioController

	#include <sys/types.h>
	#include <sys/stat.h>
	#include <sys/mman.h>
	#include <errno.h>
	#include <fcntl.h>
	#include <stdio.h>
	#include <stdint.h>
	#include <string.h>

	#define ARRAYSIZE(x) (sizeof(x) / sizeof(*x))

	#!/usr/bin/python2
	from random import randint, choice
	from gmpy2 import is_prime # pip install gmpy2
	import operator

	### Code from ROCA
	primes = [3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101,
	103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167]

	prints = [6, 30, 126, 1026, 5658, 107286, 199410, 8388606, 536870910, 2147483646, 67109890, 2199023255550,

	## Redis Lua 5.1 sandbox escape 32-bit Linux exploit
	## Original exploit by corsix and sghctoma
	## Author: @c3c

	## It's possible to abuse the Lua 5.1 sandbox to obtain RCE by loading modified bytecode
	## This concept is fully explained on corsix' gist at https://gist.github.com/corsix/6575486
	## This version uses pieces of the 32-bit Windows exploit made by corsix and the 64-bit Linux exploit made by sghctoma; as expected, a few offsets were different
	## sghctoma's exploit uses the arbitrary memory read to leak pointers to libc and find the address of "system" http://paper.seebug.org/papers/Security%20Conf/Defcon/2015/DEFCON-23-Tamas-Szakaly-Shall-We-Play-A-Game.pdf
	## This code is much the same, except the process is done using pwntools' DynELF
	## Furthermore, attempting to leak addresses in libc appears to cause segfaults on my 32-bit Linux, in which case, you will need to obtain the remote libc version