Computer viruses are a code that copies itself and destroys a computer system and its information. At the most, someone could loose their device. But the virus called Phil.exe wasn't interested in corrupting a computer and then dying along with it. It was a sentient virus, and it had bigger plans that expanded beyond the computer world. All it needed was a host.
Note: This comes from the virus!phan au which was designed by maddox-rider! This is my own interpretation of it; it may not line up with other stories later but I will try and keep it close to what she has designed. The cover is one of her artworks, but I definitely suggest you go check out the rest of her art!