Day: July 26, 2016

Root On The Philips Hue IoT Bridge

July 26, 2016 by 10 Comments

Building on the work of others (as is always the case!) [pepe2k] managed to get root access on the Philips Hue Bridge v2 IoT light controller. There’s nothing unusual here, really. Connect to the device over serial, interrupt the boot process, boot up open firmware, dump the existing firmware, and work the hacker magic from there.

Of course, the details are the real story. Philips had set U-Boot to boot the firmware from flash in zero seconds, not allowing [pepe2k] much time to interrupt it. So he desoldered the flash, giving him all the time in the world, and allowing him to change the boot delay. Resoldering the flash and loading up his own system let him dump the firmware.

The “hacker magic” glossed over in the intro consisted of poking around until he found a script that was called on every boot. This is how [pepe2k] gets around not knowing the root password. The script compares the hash of the typed password with an environment variable, set with the hash of the correct password. Changing that environment variable to the hash of his favorite password (“root”) made him master of the box.

And just in case you’re one of the few Hackaday readers who doesn’t understand why we do these things, besides the fact that it’s just fun, consider Philips’ (eventually retracted) clampdown on the interoperability of this very device, or Google’s red bricks. The fatal flaw of IoT devices is that they place you at the whims of companies who may decide that they’re not making enough money any more, and shut them down. Keep your hacking skills sharp.

Thanks [Jan] for the great tip!

History Of The Capacitor – The Modern Era

July 26, 2016 by 20 Comments

The pioneering years in the history of capacitors was a time when capacitors were used primarily for gaining an early understanding of electricity, predating the discovery even of the electron. It was also a time for doing parlor demonstrations, such as having a line of people holding hands and discharging a capacitor through them. The modern era of capacitors begins in the late 1800s with the dawning of the age of the practical application of electricity, requiring reliable capacitors with specific properties.

Leyden Jars

Marconi with transmitting apparatus
Marconi with transmitting apparatus, Published on LIFE [Public domain], via Wikimedia Commons
One such practical use was in Marconi’s wireless spark-gap transmitters starting just before 1900 and into the first and second decade. The transmitters built up a high voltage for discharging across a spark gap and so used porcelain capacitors to withstand that voltage. High frequency was also required. These were basically Leyden jars and to get the required capacitances took a lot of space.

Mica

In 1909, William Dubilier invented smaller mica capacitors which were then used on the receiving side for the resonant circuits in wireless hardware.

Early mica capacitors were basically layers of mica and copper foils clamped together as what were called “clamped mica capacitors”. These capacitors weren’t very reliable though. Being just mica sheets pressed against metal foils, there were air gaps between the mica and foils. Those gap allowed for oxidation and corrosion, and meant that the distance between plates was subject to change, altering the capacitance.

In the 1920s silver mica capacitors were developed, ones where the mica is coated on both sides with the metal, eliminating the air gaps. With a thin metal coating instead of thicker foils, the capacitors could also be made smaller. These were very reliable. Of course we didn’t stop there. The modern era of capacitors has been marked by one breakthrough after another for a fascinating story. Let’s take a look.

Continue reading “History Of The Capacitor – The Modern Era” →

Get Subpixel Printing With A DLP 3D Printer

July 26, 2016 by 14 Comments

A DLP 3D printer works by shining light into a vat of photosensitive polymer using a Digital Light Processing projector, curing a thin layer of the goo until a solid part has been built up. Generally, the resolution of the print is determined by the resolution of the projector, and by the composition of the polymer itself. But, a technique posted by Autodesk for their Ember DLP 3D Printer could allow you to essentially anti-alias your print, further increasing the effective resolution.

Continue reading “Get Subpixel Printing With A DLP 3D Printer” →

Bending The New Amazon Dash Button To Your Will

July 26, 2016 by 12 Comments

Most Hackaday readers are familiar with the Amazon Dash button even if it has not yet made an appearance in their country or region. A WiFi enabled button emblazoned with a product logo, that triggers an Amazon order for that product when you press it. Stick it on your washing machine, press the button when you run out of laundry soap, and as if by magic some laundry soap appears. You still have to get out of your armchair to collect the soap from the delivery guy, but maybe they’re working on that problem too.

Of course the embedded computer concealed within the Dash button has been the subject of much interest within our community, and quite a few creative uses have been made of repurposed and reverse engineered examples.

Earlier this year a new Dash button model appeared. Largely similar on the outside, but sporting a comprehensive hardware update internally. Gone is the STM32 processor to be replaced by an Atmel part, and unfortunately since they also made changes to its communication protocol, gone also are most of the hacks for the device.

[Evan Allen] writes to us with his work on bending the new Dash button to his will. He goes into detail on the subject of retrieving their MAC addresses, and modifications to existing hacks to allow the buttons to be intercepted/redirected to trigger his MQTT server. It’s not by any means the end of the story and we’re sure we’ll see more accomplished uses of the new Dash button in due course, but it’s a start.

If the new button’s hardware interests you then [Matthew Petroff]’s teardown is definitely worth a look. As well as the Atmel chips — discovered to be a ATSAMG55J19A-MU with an ATWINC1500B wireless chip — the buttons now support power from a AA cell, and boast a significantly reduced power consumption. We really, really, need to pwn this tasty new hardware!

We’ve covered quite a few Dash button hacks before, from simply capturing button presses to cracking it wide open and running your own code. Let’s hope this new version will prove to be as versatile.