Achieving information security is a key aspect of any information system, and is manifested in the protection of the basic elements of information security: confidentiality, integrity and availability. With the progress of mobile technology and applications, more and more threats are developing, and the aforementioned elements of information security are being breached. Breaches are caused by malicious attackers that come in various forms such as malware, hacking, physical and APT attacks. This final paper provides insight into a particular type of information threat and itsimpact on system security. There are many types of malware, and some of the most common are viruses, Trojan horses, worms and spyware. A few sentences have been written about each type of attack in order to get a comprehensive impression of the risks and harmful consequences that occur when a device is infected by these types of attacks. Since the topic of the work is based on mobile device systems and applications, after researching a lot of literature, an analysis of malicious attacks on Android and iOS devices was performed. The analysis led to the conclusion that mobile operating systems provide a high level of protection for the system, as well as for their users. The final paper also includes measures to protect the device from malicious attacks, which are implemented in case of an existing infection or to prevent malicious attacks. Proper analysis, identification of system vulnerabilities, but also compliance and application of appropriate security measures will reduce the risk of potential attacks and allow users to preserve their security and privacy in the mobile environment.