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Found some time for another Bluetooth rant :) This time it's going to be about BlueZ , the Linux Bluetooth stack. Note that there are other Bluetooth stacks for Linux such as BTstack , but I didn't find the time to play around with these, and BlueZ is still what you get these days if you install a normal Linux distribution. This is my view on about BlueZ and a couple of things might be over-simplified. Feel free to add comments to this post if anything is wrong or is better explained elsewhere. However, I found that there is no good overview from a programming and hacking perspective, and often times I get questions about patching certain things within InternalBlue that have a root cause deep down in the Linux kernel. BlueZ is missing documentation. In fact, I ended up using dynamic debugging here and there to understand which functions are still called and which are deprecated. Otherwise, this blog post would not be needed for an open-source project m) Linux Bluetooth stack vs

The perfect Bluetooth research tooling doesn't exist ;) But since I'm maintaining InternalBlue I can provide you with an overview of compatible devices and the advantages or shortcomings of all of these. There is some open tooling for Bluetooth LE out there. Bluetooth LE is mostly used in IoT devices and modern gadgets. When it comes to Classic Bluetooth, which is still used a lot for audio devices and data transfer like tethering, you need to buy professional equipment or deal with very bad open-source implementations based on software-defined radios (SDRs). A brief overview of this can be found in my Bluetooth Hacking 101 talk from last year. Despite not using anything based on SDRs or microcontrollers, I have a huge variety of devices. All of them have Broadcom (or "Cypress") Bluetooth chips. So, here is a minimal (seriously!) selection required to do some meaningful Bluetooth research that includes a couple of generations of devices and the possibility to test v

When looking into the most recent Bluetooth patches of the Samsung Galaxy Note 20 5G, I found something interesting. Once again, it's about the Random Number Generator (RNG). Jörn, Felix and me already published a WOOT paper about this last year. But there were some updates since then, which will be covered in this blog post. Oh, and it also contains assembly for the curious reverse engineer, additional honest opinions (I hope reviewer 2 will never find my blog), rants, and explanations for people who are new to Bluetooth. If you already saw the talk or read the paper, you might want to skip forward to "The unexpected patch". But you will miss some ranting!!!11! Why should anyone look into a random number generator? A RNG is one of those dragons that live deep inside the firmware or even hardware. Just don't look at them. Otherwise, something might break :) The Bluetooth Core Specification , currently at version 5.2, specifies that a Bluetooth chip has to provide a F

Due to some vulnerabilities found recently, Broadcom started to see the "Bluetooth host -> Bluetooth controller" communication as an attack surface. In Bluetooth terminology, the host is the operating system with a Bluetooth daemon, e.g. iOS or Android, and the controller is Broadcom's Bluetooth chip. A lot of manufacturers see that as attack surface - to protect their intellectual property or to prevent that people use their smartphone as software-defined radio. Moreover, it raises the bar for initial exploit development. Other manufacturers protect their chips with secure boot. This means that they sign their firmware. The chip has a minimal bootloader, which loads the vendor's firmware for that chip, checks the signature, and then boots it. Thus, for a lot of chips, the first step is to find a secure boot bypass or to find a vendor/device that has secure boot disabled. Broadcom had an interesting idea on that, for both Bluetooth and Wi-Fi chips. They store their

A lot of people asked me about my OBS setup. So I'm releasing a few details here. Feel free to ask questions in case I forgot anything. Recording on a laptop Yes, I'm recording my videos on a laptop. Initially, I tried a 5 year old X1 Yoga running Linux. While this works okay-ish, once I used a dual camera setup, my recordings sometimes had very low frames per second and other weird effects. Using the cheapest MacBook Pro 2019 model (the 1.4 GHz variant with 8 GB RAM), recording works after a reboot and closing all other programs, even when running two OBS instances at once. Since upgrading to a MacBook Pro 2020 (2 GHz, 16 GB RAM) all these issues are gone. Always make a couple of test recordings that last longer than a minute to see if your laptop can handle the load. I had to re-record one of my talks that I recorded on the X1 Yoga because 5 frames per second and lagging audio didn't make me happy ;) Smartphone camera Webcams suck. Even the one in my MacBook Pro 2020. If