• The most widespread are phishing emails. All of us will have happened to receive emails from couriers, or with fake bills attached: opening attachments or links in the email allows malware infiltration.
• through browsing compromised sites. Within fake or hacker-infected sites, banner ads or buttons are placed that invite us to click. At that point, we will be directed to malicious sites, different from the original, where the download of the malware will take place.
• using a removable medium, for example, a USB stick containing the malicious software inside other software that is downloaded. For example, free programs that promise us to “crack” expensive software to use them without paying, inside which malware may reside.
• direct intrusions into local networks through security holes in the virtual perimeter.
• through exploitation of vulnerabilities in the operating system or applications installed on victims’ devices.

Typically, a malware is unable to physically damage affected hardware or network devices with its malicious code. Therefore, the only way to detect the presence of malware in a computer system is by analyzing any abnormal and suspicious behavior, such as decreasing computer performance, unauthorized modification of the browser’s home page, and continuous crashing of the operating system.

To remove all possible malicious code from a device, it is advisable to rely on an antimalware program. Even though efficient, antimalware alone may not be enough to defend against and prevent. Once the “physical” cleaning of malware is finished, it is then advisable to change the passwords of the PC, smartphone, or tablet, as well as the one used for e-mail and various e-commerce sites.

Trojans or “trojan horses” are a particular type of malware that criminals can use to take complete control of our device, mobile or stationary, and perform almost any type of operation: blocking, modifying, deleting data, or knocking out the computer system.
This virus presents itself as a seemingly useful file: it hides inside formally harmless programs that prompt the user to install them. Once downloaded, it acts silently, without the computer owner knowing its nature, thus enabling criminals to perform various actions:

• create backdoors, suitable for allowing the entry of other malware or a hacker
• spy on the actions of the computer owner, in order to take confidential data and information;
• turn the computer into a tool at the complete service of the hacker.

Trojans do not spread on their own but must be downloaded by the user who has an active role in propagating the malicious program.