Jammers are used to jam signals in the 2.4 GHz band

Of course, you have thought about a tool that can block WiFi network signals in your area. At the security conference organized by Noilson Caio Teixeira de Araújo (Brazil), ESET and We Live Security provided special Spanish support. In one of the ekoparty seminars, we saw today how we can build to achieve this The target device can only have a few crystals, some resistors and some antennas.

In addition to all malicious applications that may occur, we will also find that in most cases, we can properly use this technology to protect ourselves. How to carry out interference attacks, first of all, it should be noted that these devices are called jammer devices, in very simple terms, it is a signal generator that interferes with wireless communication. There are two types of interference or interference attacks that may interfere with the data communication of the receiver. The first is the so-called speckle, whose purpose is to destroy a certain frequency. When it comes to affecting multiple channels at the same time, we will face barrage interference.

In both cases, the appropriate frequency must be found to make the attack effective and have enough power to replace the original signal. It should also be noted that the victims of these attacks are clients who cannot connect to the network. In any case, the AP can continue to operate normally, and only those devices that are close enough to the sending device can be lucky to connect.

What is the concept behind interference? These devices have an oscillator or signal generator, which allows us to amplify the signal through the antenna to achieve greater coverage. We need to look for a signal that resonates with the carrier frequency we want to interfere with, thereby preventing the transmission of information. Depending on the antenna used, the device may range from a few meters to several kilometers. The portable jammer  used during the demonstration was used to interfere with signals in the 2.4 GHz band. This band is called ISM and covers unprotected spectrum that can be used without permission. Protocols such as WiFi or Bluethoot actually work in this frequency band.

How do we use security issues? As we all know, WiFi uses 11 channels for operation. Each channel has a center frequency, so these jammers try to interfere with frequencies between 2402 GHz and 2483 GHz. Now, for security reasons, the interesting thing about using these devices is. Three points were analyzed in the dialogue:

1. It can be used to prevent Roguer AP in an enterprise environment. This is nothing more than preventing third parties (for example, from their mobile devices) from generating WiFi connection points via an Internet connection.

2. Avoid information leakage through wireless data transmission, so that data exchange can be carried out abroad.

3. Delete “malicious twins” on unauthenticated networks. In this way, we can only keep a few communication channels up and running, which limits the possibility of generating malicious networks to deceive our users.

It is very important to warn that these devices may be restricted or even prohibited in some countries. Therefore, advice must be sought in any case to avoid ignoring the applicable regulations in various countries.