Although there are many things that need protection, the main ones are those that appear on the Internet. Many harmful programs instal themselves surreptitiously on the user’s computer and their infiltration cannot be influenced without proper protection. When this happens, it is usually too late and a thorough inspection of the whole computer is needed. Many viruses and hackers on many mobile devices are becoming an increasing problem in today’s protection of personal information. Viruses for mobile phones have been known for a long time, yet the majority of users of these devices infected with malware are not aware of the infection because they do not know for the existence of security vulnerabilities of their operating systems. This paper presents an overview of the corresponding operating systems that support encryption in relation to the selected mobile phone, which can lead to a greater level of security of the device. There are many different types of harmful software that affect the security of mobile devices as well as personal computer systems of users, such as viruses, Trojans, malware, bootkits and others. Master boot sector, the first sector of the hard disk in a computer system which contains the code needed to run the operating system is often the target of specific types of viruses called bootkits or rootkits. Since they are invisible to the operating system it is very difficult to remove them from an infected computer. Therefore the review of the existence of vulnerabilities in operating systems offered in this paper is an attempt at drawing attention to their possible attacks.