Hackaday Links: February 16, 2014

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[Moogle] wrote in to see if anyone can figure out why his unused electrolytic capacitors are popping. This is the behavior you see in populated caps whose electrolyte dries out. But these are still in his parts bin. Anyone know why they would pop when going unused?

We see a lot of BIOS flashing hacks; but it’s always a handy thing to know about when you get in a bind. Here [Adan] shows us how to reflash a corrupt BIOS using a Tiva C Launchpad board.

Wanting to hack together her own blow gun [Carlyn] scrapped a handheld vacuum cleaner. When she discovered the pump could not easily be converted from suck to blow she made a handheld suction manipulator which picks up paper plates and a few slightly heavier objects.

Unfortunately a drill press is not one of the tools we have in our lair right now. If we did, this tip about using it to help tap threads in a hole would come in really hand.

Retro computing fans will appreciate this Z80 computer build (translated). It’s a fairly large mainboard with plenty of chips, resistors, buttons, and seven segment displays. Excellent. [Thanks Daniel]

We start to drool a little bit when we see a teardown post that shows off a piece of equipment really well. We’ve already reached for a bib to catch the slobber from pawing our way through [David's] teardown of an HP 6010A bench supply.

Arduino Uno BIOS flasher

We’ve seen the Arduino used to flash BIOS chips several times now. But these hacks are almost always the result of a bad flash. This time around [GNUtoo] is interested in putting a tool in your hands which can be used to flash Coreboot to your motherboard. His offering uses the Arduino Uno, but there are several other hardware options covered as well.

The firmware makes use of the serprog-duino library which was crafted at writing to flash memory chips. On the computer side of things the flashrom package pushes the BIOS image to the Arduino. The nice thing is the flashrom is a common packge in Linux repositories so it’s probably just an apt-get away.

The process isn’t fast, taking about ten minutes to program a 1 Mb chip. But if you’re just interested in loading an open source BIOS alternative this is easy to set up.

Brute Force BIOS Hacking Using the Arduino

This clever hack uses an Arduino to do a brute force attack on a computer’s BIOS. In theory, this technique could be used for other programs, but it’s use would be limited since there’s no way to account for too many wrong passwords.

The Arduino generates and outputs the possible password emulating a USB keyboard. When this is done, the pixel in the middle of the screen is read. This is done by reading the analog red signal synced up with the corresponding horizontal and vertical pulses. As with any hack, there were some programming issues that had to be overcome (including one that locked up the keyboard emulator), but this was resolved, and the code is available if you wan to build your own.

Hardware for this build is simple, involving a LCD output, a button to stop everything, and a couple diodes to get the USB keyboard working correctly. This hack turned out quite nicely, and the code and schematics are included!

Recovering a corrupted EEE PC BIOS

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[Jeremy] had an ASUS EEE PC 1000HE netbook on his hands which had succumbed to a corrupted BIOS. In most situations, people replace a motherboard when the BIOS is damaged beyond repair, but considering the price of motherboards, especially those built for portable devices, he simply refused to go that route.

Instead, he took it apart and did a little investigation to find out what SPI flash chip ASUS used in the netbook. With that information in hand, he put together an SPI flash programmer using a breadboard and a DLP-USB1232H USB to UART module. He couldn’t program the flash chip in-circuit, so he had to desolder it and deadbugged it onto his programmer. Using a few Linux-based flashing tools, he was able to reprogram the chip with a functioning BIOS in short order, saving him from a costly motherboard replacement.

While some motherboard manufacturers have built in secondary BIOS chips to prevent the need for this sort of recovery, it’s nice to know that the process is relatively straightforward, provided you have some basic soldering and Linux skills.

This also isn’t the first time we’ve seen someone recover an EEE PC from the brink – if you’re looking for an Arduino-based alternative, be sure to check this out.

Laptop BIOS password recovery using a simple dongle

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In his line of work, Instructables user [Harrymatic] sees a lot of Toshiba laptops come across his desk, some of which are protected with a BIOS password. Typically, in order to make it past the BIOS lockout and get access to the computer,  he would have to open the laptop case and short the CMOS reset pins or pull the CMOS battery. The process is quite tedious, so he prefers to use a simpler method, a parallel loopback plug.

The plug itself is pretty easy to build. After soldering a handful of wires to the back of a standard male D-sub 25 connector in the arrangement shown in his tutorial, he was good to go. When a laptop is powered on with the plug inserted, the BIOS password is cleared, and the computer can be used as normal.

It should be said that he is only positive that this works with the specific Toshiba laptop models he lists in his writeup. It would be interesting to see this tried with other laptop brands to see if they respond in the same way.
Since no laptops are manufactured with parallel ports these days, do you have some tips or tricks for recovering laptop BIOS passwords? Be sure to share them with us in the comments.

Grinding down your computer to just 8.5 watts

What can you do to make sure your system is running as efficiently as possible? Take a page out of [Mux's] book, who went to great lengths to measure and adjust his system for ultimate efficiency (translated). What he ended up with is 8.5 Watts of consumption at idle and about 50 Watts under load. Luckily he posted a six-part series with all of the details.

Some of the changes he made were in software, like reducing voltage to certain hardware by adjusting BIOS settings, and installing display drivers that put the screen into the proper sleep mode. Others were hardware changes like swapping out the power supply with a hacked PicoPSU and removing unnecessary parts from the motherboard like the MAX232 com-port chip. Looks like we need to audit our always-on MythTV box and see if we can apply any of these power-saving techniques.

[Thanks Gijs]

BIOS password cracking

[Dogbert] took a look at the security that goes into BIOS passwords on many laptops. He starts off with a little background about how the systems work. People are bound to forget their passwords, so when you enter a wrong one three times in a row you get a message similar to the one above that locks you out until all power is removed from the system (then you get three more tries). But check out that five-digit number in the picture. That’s a checksum of the password. Some BIOS versions display it automatically, some require you to hold down a certain key during POST, but it’s the pivotal data needed to crack the password.

[Dogbert's] post doesn’t go into verbose detail about the algorithms he uses to brute force the passwords. But he has posted the Python scripts he uses to do so. Learning how to generate the passwords based on the checksum is as simple as studying the code, which is often the best way to learn.