In principle, all electronic devices that are either connected to the Internet or have a removable medium, such as USB, CD-ROM, and external hard drive, can become infected with malware. Criminals take a variety of approaches when attempting to plant malware on users. The following options are particularly popular:
Malware in email attachment
You receive an e-mail that supposedly comes from a trusted provider, such as your bank. Attached to the email is a file containing malware. Beware of file formats such as .exe or .scr or double file extensions such as pdf.exe. If you open such a file, it would be like opening the front door for a burglar and inviting him in. Links in the text of an e-mail that appear harmless can also lead to infected websites, which automatically run malicious software in the browser when they are called up.
For example, another common method used by criminals is to make PDFs or Office documents an entry point into your system via dynamic content and macros. A macro is a sequence of commands and instructions to perform a task automatically. To avoid unnecessary risks, macros should be disabled for untrustworthy documents.
Drive by download
The infection occurs by accessing a manipulated website. But even reputable websites can be contaminated with malicious code through manipulated advertising banners. The malicious program is installed without your interaction simply by calling up the page, with the perpetrators exploiting security gaps that have not yet been closed. An open security gap is like a slanted window through which burglars can get into the house.
It is therefore particularly important to constantly install new updates of the operating system. In this way, security gaps are continuously closed. You can find the update settings under Windows, for example, if you open the system settings and search for Windows update there.
Malspam and social networks
You can receive harmful links and file attachments either by email or as a message on social networks. For example, someone you think you know sends you a bill or a photo, or recommends an interesting website. Sometimes it can even happen that you receive suspicious messages from the e-mail addresses of real friends and acquaintances. In this case, perpetrators may have hacked and taken over their accounts or the devices are infected with malware. The mail accounts are now being misused to send malware. Opening the file or clicking the link installs the malware program.
Devices such as USB sticks or external hard drives can contain infected files. If you now transfer data between two devices for the purpose of data exchange, for example using a USB stick, malware can be transferred from one infected device to the other previously uninfected device.
They are another source of danger, including public WLAN, because you cannot know whether and how they are secured. In hotels, when using hotspots, but also with the computers and mobile devices of friends and acquaintances, you should therefore be careful and avoid third-party networks and devices if possible.
At the same time, you should be sparing with access to your own WLAN at home. External devices can also introduce infections. It is therefore better to set up a guest WLAN for guests. You can usually find instructions on how to do this on the website of your router manufacturer. Likewise, it is strongly recommended to use such a separate WLAN if you want to set up and use smart home devices in your home.