If you get file with
img extension, don’t open them.
You may have in your computer viruses which are not active and then they are harmless. The virus is usually hiden in the software code and is activated by running the program. There are more methods how to do it but the most popular these days are emails with infected files. The file contain the virus or redirects you to a webpage where you download virus and it is activated automaticaly or you must click on the downloaded file.
The danger of
img files is in good psychological targeting. You get email where is written that you are getting image which contains invoice or whatever. So you see in the email file with
img extension and logicaly assume that it may be an image. Unfortunately
img files are Apple version of
iso files and they are used for creating disc images (copies of disc content). So in the
img file there are hidden other files which may even be activated automaticaly. The best solution is to block completely emails with
img files at the mail server. Then normal useres wouldn’t even have to think about this threat.