An attacker can use a jammer to interrupt the radio connection. Suppressing or preventing radio transmission may, for example, interrupt the image of the surveillance camera. These attacks must be considered protection.
The signal jammer sends a signal of the same frequency (noise or pulse) with a certain strength on a certain frequency, thereby superimposing the original transmission. If jammers are used exclusively, they are called strategic jammers. These devices are also called jammers, and the process is called noise interference.
The jammer can be used in various radio protocols, such as Bluetooth, WiFi, GSM, UMTS, LTE and GPS. Therefore, the specific frequency of the radio protocol is interfered. There are very simple and small devices that can only interfere with radio signals within a limited radius. For example, there is a small adapter for car cigarette lighters that has the function of interfering with GPS signals. A portable device with a battery can reach a maximum distance of 20 meters under optimal conditions, depending on the model. Usually, they interfere with the signal in the room. Powerful fixed equipment can reach a range of 80 meters.
In Germany, the use of jammers is illegal. They are mainly used by investigative agencies and military departments. Some of them are used in prisons to prevent prisoners from making illegal communications. The challenge here is that no outside signals are blocked, such as mobile phone signals for emergency calls. In foreign countries, jammers are sometimes used in movie theaters and theaters so that the incident will not be interrupted by mobile phone signals. Another use is, for example, to block control signals from drones.
If an attacker uses this interference transmitter, it can be used to block the radio link of the surveillance camera or the window sensor of the alarm system. Therefore, a broken connection must always be equivalent to an alarm. In addition, interference can be detected by continuously testing the radio connection between two components using a cable connection. If the connection is interrupted, the jammer is active. Alternatively, but also technically more difficult to solve, you can test the signal level, the strength of the radio signal. If a new strong radiation source is detected here, it may be an interfering transmitter.
