The offer or Gemma, what's the difference? Today we are taking a look at it and explore how they work and whether or not they are safe to use. So, a Gemma works by creating a lot of noise to make others unable to understand any signals. Depending on the frequency of these signals, a Gemma can target a specific communication protocol like GPS. Upon activation, a Gemma will effectively block anyone in its physical and frequency range. Imagine you're talking to someone and suddenly there's music so loud your ears heard. Now go. Only when you get out of range, the music isn't as loud anymore and you start to hear the surroundings again. That's essentially what a Gemma does, just on different frequencies, depending on the protocol or device you're trying to target. There are a variety of Gemmas available for all kinds of frequency ranges and they are probably all equally illegal to sell and use where you live. A Gemma doesn't differentiate between devices. It affects anyone and anything in its range. They don't care if you want to access the internet or make an emergency protocol. They don't differentiate between the firefighters trying to communicate and a person just calling their friend. They just attack everything, which is why they are so illegal. As our world becomes more and more connected, we rely more and more on a variety of wireless communications. So disrupting these systems can cause huge irreversible damage. So given these circumstances, it probably isn't a surprise that the FCC even has a dedicated page about Gemmas, where they state the following. Signal-jamming devices can prevent you and others from making 911 and other emergency calls and pose serious risks to public safety communications as well as interfere with other forms of day-to-day communications. The use of a phone Gemma GPS blocker or other signal-jamming device designed to intentionally block Gemma interfere with authorized radio communications is a violation of federal law. There are no exemptions for use within a business classroom residence or vehicle. It is also unlawful to advertise, sell, distribute, import or otherwise market gemming devices to consumers in the United States. The use or marketing of a Gemma in the United States may subject you to substantial monetary penalties, seizure of the unlawful equipment and criminal sanctions including imprisonment. So Wi-Fi has a service called the authentication. It is used to terminate the authentication of a client or in other words, to disconnect the device from the network. It works by sending out a notification to the device that is to be disconnected. The device cannot refuse this packet. The D-Off attack exploits this feature by continuously sending these the authentication frames to a selected target. This way you can effectively block a connection. The target device is still able to reconnect but it will only be able to establish a connection until it receives orders to disconnect again. So it's basically like going shopping and every time you try to enter the building someone commands you to leave. Luckily Wi-Fi also has a solution for this exploit. It's called protected management frames or PMF foreshort. They were already introduced back in 2009 with the iTriplee 802.11W standouts. When this feature is active, the authentication frames and other management frames will be checked for integrity and the receiver will ignore them if this check fails which means you can't simply send such a packet because the receiver realizes that it comes from an unverified source. I wouldn't say it's impossible to break this security feature but it makes the whole attack a lot harder. I created this project back in 2017. Back then it was meant as a proof of concept for showcasing how easy it is to attack Wi-Fi networks using the E-D-Offentication exploit. It runs on the ESP8266. A small, affordable, Arduino-compatible microcontroller that comes with 2.4 GHz Wi-Fi built-in. Since version 3 of this project it has evolved into a capable tool for Wi-Fi security research that can do much more than just simply D-Off devices. If you want to learn more about the tool be sure to check the video description. We will link everything. We also have a bunch of videos about this project on our YouTube channel. So be sure to check those out. While a very illegal Gemma, as we just learned, works by emitting noise. A D-Offent doesn't allow you to simply attack all networks in range because of the authentication packet which by the way is part of the official standard is always addressed to certain device or network which means you have to first scan for nearby devices and select the targets and then start the attack. Basically you need to find out the addresses of the devices you're trying to attack. So if you choose to attack critical infrastructure you are responsible for that and you may have to face the consequences. But you can still use this to test the security of your own devices and networks, learn about Wi-Fi security and teach others about the topic without ever risking to unintentionally block someone else's communication. If however you build a device to automatically find and de-authenticate all connections in range, you would end up with something that is very close to Gemma and you can expect the same penalties for using such a device. So in short, a Gemma attacks everything in its range without giving you control over which devices you attack. But a tool like our ESP8266D offer attacks only those you tell it to for a maximum of five minutes and is furthermore unable to attack everything at once. So as long as you're used for pen testing, research, and educational purposes and don't cause any harm to others, you are fine. We plan to continue our work towards educating about hacking with microcontrollers. And this video is part of that. If you want to do your own research on this matter, we have linked our sources below. And if you have any further questions, feel free to join our Discord community server. If you like to support our work, visit spaceon.store where you can get a de-offer of your own and maybe some dope merch in the future. Thank you so much for watching. As I said, this is part of a series where we try to educate about things like this. And yeah, I see you in the next video.