When malware gets onto your system, one of the first things it may do is disable your antivirus scanner.
An EICAR test file will help you determine whether your antivirus scanner has been disabled. EICAR is a non-viral string of code that most antivirus software have included in their signature definition files specifically for this purpose.
An EICAR test file can be easily created using any text editor, such as Notepad. To create an EICAR test file, copy and paste the following line into a blank Notepad file:
Save the file as EICAR.COM. It is now ready for testing. In fact, if your active protection was working properly, the simple act of saving the file should have triggered an alert.