# Review of Smart-Home Security Using the Internet of Things
## 4 Analysis and Discussions of the IoT Setting
### Threats Faced by a Smart Home and Related Countermeasures
#### 4.2.4 Physical Layer Analysis  
The installation of an electric power supply in smart devices is a building block of the IoT system. Power failure is a factor that makes the system particularly vulnerable [167; 168]. There should be a mechanism that can protect the devices and the system from a power outage, which can be caused either due to extreme weather phenomena or due to the intervention of a third party to create fertile ground for attacks. An environmental attack is considered an attack that a device experiences due to a weather phenomenon [169; 170]. For example, a sensor can be damaged when exposed to heavy rain or falling snow. This may lead to its malfunction and consequently affect the efficiency of the entire system, causing many problems. Smart devices, most of the time, operate with a specific supply of electrical power, without the possibility of backup energy sources in case of exhaustion or interruption of the central supply. When these devices run out of power, they automatically go into low-power mode. This results in their limited operation, making them unable to meet 100% of the system's needs or sending incorrect information [171; 172]. These are hardware failures, leading to network and system failures, and it only takes one device to be underpowered due to low power for this to happen. A sensitive part of the system is the wireless connections between its devices, where they are targeted by attackers who bombard them with radio signals, known as jamming, in order to interfere with their communication. This can lead to total or partial network collapse, depending on signal strength [173]. However, even in the partial malfunction of the network, in order for the affected nodes to do the required filtering, they lose a large percentage of their power, since they are forced to transmit the data when they regain communication, causing many side-effects, as described above. Also, another attack is to inject malware through the debugging interface [169]. A malicious device can spoof the network by pretending to be an authenticated device and spread the malware to all nodes, thereby enabling a third party to intercept sensitive information or even shut down the entire system. One type of attack on the physical layer is a bombardment of the network with noise signals, i.e., unnecessary and useless information, interfering with the operation of the Radio Frequency Identification (RFID) part. The RFID is underpowered and cannot send information to the devices with the required power [33]. Finally, another attack on this layer is the creation of a clone device, with the same characteristics as a certified device, such as the manufacturer, software, and configurations, in order to trick the system, deceiving the RFID counterpart and copying the tags [174; 175]. The clone device, after entering the network, spreads malicious software to all nodes in the network, with the aim of intercepting or destroying it. The attacker aims to understand the security protocols and try to copy the tags [30], writing and sending data that will modify the behavior of the system [103; 106; 107]. The physical layer consists of the system hardware (i.e., the smart devices), but also the devices and components used to interface with each other and with the Internet. A vulnerable point on the physical level is the electricity supply mechanism, where during a power outage which can also be due to extreme weather conditions, the devices are deactivated and a huge hole in the system's security is created. Also, when devices run out of power, they go into low-power mode and start underperforming. Smart devices are vulnerable to attacks, as described above, before and when they are under conditions of extreme weather phenomena. A solution to this includes the deployment of devices in places that will not expose them to those natural phenomena. Cloning system devices by cloning RFID tags is also a popular attack method. A proposed solution is to hash double collisions with a vector of exact metrics.