Reverse Engineering

201 Articles

Diagram from the blog post, showing how GATT communication capture works

Hacking BLE To Liberate Your Exercise Equipment

January 4, 2024 by 17 Comments

It’s a story we’ve heard many times before: if you want to get your data from the Domyos EL500 elliptical trainer, you need to use a proprietary smartphone application that talks to the device over Bluetooth Low-Energy (BLE). To add insult to injury, the only way to the software will export your workout information is by producing a JPG image of a graph. This just won’t do, so [Juan Carlos Jiménez] gives us yet another extensive write-up, which provides an excellent introduction to practical BLE hacking.

He walks us through BLE GATT (Generic Attribute Profile), the most common way such devices work, different stages of the connection process, and the tools you can use for sniffing an active connection. Then [Juan] shows us a few captured messages, how to figure out packet types, and moves into the tastiest part — using an ESP32 to man-in-the-middle (MITM) the connection.

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Current-Based Side-Channel Attacks, Two Ways

January 4, 2024 by 9 Comments

Funny things can happen when a security researcher and an electronics engineer specializing in high-speed circuits get together. At least they did when [Limpkin] met [Roman], which resulted in two interesting hardware solutions for side-channel attacks.

As [Limpkin] relates it, the tale began when he shared an office with [Roman Korkikian], a security researcher looking into current-based attacks on the crypto engine inside ESP32s. The idea goes that by monitoring the current consumption of the processor during cryptographic operations, you can derive enough data to figure out how it works. It’s difficult to tease a useful signal from the noise, though, and [Roman]’s setup with long wire runs and a noisy current probe wasn’t helping at all. So [Limpkin] decided to pitch in.

The first board he designed was based on a balun, which he used to isolate the device under test from the amplification stage. He found a 1:8 balun, normally used to match impedances in RF circuits, and used its primary as a shunt resistance between the power supply — a CR1220 coin cell — and the DUT. The amplifier stage is a pair of low-noise RF amps; a variable attenuator was added between the amp stages on a second version of the board.

Board number two took a different tack; rather than use a balun, [Limpkin] chose a simple shunt resistor with a few twists. To measure the low-current signal on top of the ESP32’s baseline draw would require such a large shunt resistor that the microcontroller wouldn’t even boot, so he instead used an OPA855 wideband low-noise op-amp as an amplified shunt. The output of that stage goes through the same variable attenuator as the first board, and then to another OPA855 gain stage. The board is entirely battery-powered, relying on nice, quiet 18650s to power both the DUT and the shunt.

How well does it work? We’ll let you watch the talk below and make up your own mind, but since they’ve used these simple circuits to break a range of different chips, we’d say this approach a winner.

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The controller after the rebuild, looking just like the stock controller but with an external antenna attached

An Extensive Walkthrough On Building Your Own KSP Controller

January 3, 2024 by 10 Comments

Having a game-tailored controller is a level-up in more ways than one, letting you perform in-game actions quickly and intuitively, instead of trying to map your actions to a clunky combination of keyboard and mouse movements. [abzman] took the Pelco KBD300A, a DVR-intended camera controller panel with a joystick, reverse-engineered it, and then rebuilt it into a Kerbal Space Program controller. What’s more, he documented every detail along the way!

The write-up is so extensive, it’s four separate posts — all of them worth reading without a doubt. In the first post, he describes the original hardware, the process of reverse-engineering it, and a few tips for your own RE journeys. Next, he covers about making his own board, showing all the small decisions he’s had to make, with plenty of KiCad screenshots. If you are on the lookout for designing such a board, there’s plenty to learn!

The original hardware didn’t go down without a fight — the third post talks about taming the seven-segment displays, the onboard joystick, and fighting with the key matrix wired in exactly the way you wouldn’t want. In the end, he shows us how you could tie a controller easily into Kerbal Space Program.

One more piece of hardware liberated, one more win for the hacker world. Whether it’s a Macintosh SE, a classic ThinkPad, or even a generic rotary tool, these upgrades are always a joy to see. If you wanted to learn to do such an upgrade yourself, here’s us showing how you can pull this off with a classic Sony Vaio!

37C3: When Apple Ditches Lightning, Hack USB-C

December 30, 2023 by 11 Comments

[Thomas Roth], aka [Ghidraninja], and author of the [Stacksmashing] YouTube channel, investigated Apple’s Lightning port and created a cool debugging tool that allowed one to get JTAG on the device. Then, Apple went to USB-C for their new phones, and all his work went to waste. Oh well, start again — and take a look at USB-C.

Turns out, though, that the iPhone 15 uses the vendor-defined messages (VDM) capability of USB-PD to get all sorts of fun features out. Others had explored the VDM capabilities on Mac notebooks, and it turns out that the VDM messages on the phone are the same. Some more fiddling, and he got a serial port and JTAG up and running. But JTAG is locked down in the production devices, so that will have to wait for an iPhone 15 jailbreak. So he went poking around elsewhere.

He found some other funny signals that turned out to be System Power Management Interface (SPMI), one of the horribly closed and NDA-documented dialects owned by the MIPI Alliance. Digging around on the Interwebs, he found enough documentation to build an open-source SPMI plugin that he said should be out on his GitHub soon.

The end result? He reworked his old Lightning hardware tool for USB-C and poked around enough in the various available protocols to get a foothold on serial, JTAG, and SPMI. This is just the beginning, but if you’re interested in playing with the new iPhone, this talk is a great place to start. Want to know all about USB-C? We’ve got plenty of reading for you.

Unbricking Trains, Uncovering Shady Behavior

December 28, 2023 by 48 Comments

The first clue was that a number of locomotives started malfunctioning with exactly 1,000,000 km on the odometer. And when the company with the contract for servicing them couldn’t figure out why, they typed “Polish hackers” into a search engine, and found our heroes [Redford], [q3k], and [MrTick]. What follows is a story of industrial skullduggery, CAN bus sniffing, obscure reverse engineering, and heavy rolling stock, and a fantastically entertaining talk.

Cutting straight to the punchline, the manufacturer of the engines in question apparently also makes a lot of money on the service contracts, and included logic bombs in the firmware that would ensure that revenue stream while thwarting independent repair shops. They also included “cheat codes” that simply unlocked the conditions, which the Polish hackers uncovered as well. Perhaps the most blatant evidence of malfeasance, though, was that there were actually checks in some versions of the firmware that geofenced out the competitors’ repair shops.

We shouldn’t spoil too much more of the talk, and there’s active investigation and legal action pending, but the smoking guns are incredibly smoky. The theme of this year’s Chaos Communication Congress is “Unlocked”, and you couldn’t ask for a better demonstration of why it’s absolutely in the public interest that hackers gotta hack. Of course, [Daniel Lange] and [Felix Domke]’s reverse engineering of the VW Dieselgate ECU shenanigans, another all-time favorite, also comes to mind.

Reverse-Engineering The Stadia Controller Bluetooth Switching Procedure

December 19, 2023 by 11 Comments

Ever since the demise of Google’s Stadia game streaming service, the associated Stadia controllers have found themselves in limbo, with the only way to switch them from the proprietary WiFi mode to Bluetooth by connecting to a special Google website. Yet as [Gary] found out, all this website does is flash a firmware file via WebUSB and WebHID over the original Stadia firmware with a generic Bluetooth controller firmware image. This is the reason why it’s a one-way process, but this wasn’t to [Gary]’s liking, so he figured out how to flash the controller himself, with the option to flash the original Stadia firmware or something else on it later, too.

[Gary]’s stadiatool follows the same procedure as the Google Stadia website, just implemented in Python and outside the control of Google. Although Google has recently announced that it will keep the Bluetooth switching website online one year longer – until December 31st 2024 – at some point this service will go away and only projects like [Gary]’s together with squirreled away firmware images can still save any stray Stadia controllers that will inevitably discovered in the back of a warehouse in the future.

Although we reported on the demise of Stadia when it happened in January of 2023, as Ars Technica notes it was common in 2022 to buy into Stadia and get a controller manufactured in the 2019 launch year, suggesting massive overproduction.

Hacking An NFC E-Paper Display From Waveshare With Mystery MCU

December 18, 2023 by 15 Comments

These days e-paper (eInk) displays are everywhere, with stores being one of the largest users of smaller, monochrome versions of these persistent displays. This has also made them a solid target of hackers who seek to not only reverse-engineer and reuse discarded ones, but also ones sold to consumers, with [Aaron Christophel] recently reverse-engineering and flashing custom firmware (GitHub source) to a Waveshare 2.13″ NFC-Powered E-Paper display.

What’s perhaps most notable is how locked-down and devoid of documentation these devices are. The board [Aaron] looked at did not have any markings on the main IC, and Waveshare did not provide more information other than the Android and iOS apps. This led to some matching of various NFC-enabled MCUs with the pinout, with the Chivotech TN2115S2 rolling out as the most likely candidate. This is an 8 MHz Cortex-M0 MCU with not only NFC, but also an energy harvesting feature (up to 300 mW), which is why this e-paper tag can update the display without external power or a battery.

With the Chivotech datasheet being rather sparse, more reverse-engineering needed to be done, which included dumping the firmware and exploring it with Ghidra. During this, the secret key was discovered to make the Flash writeable along with how to control the peripherals and display. With this knowledge it’s now possible to make this tag display update without being limited by manufacturer-supplied tools and software, making it infinitely more useful.

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