[VadeRetro]

Whether or not viruses meet all definitions of "life," they evolve. Their reproduction is typically less passive than that of the hypothesized earliest self-replicators on Earth. For instance, viruses often have some kind of protective husk with little booby-trap mechanisms to inject the nucleic acid payload into a cell upon proper triggering.

What you've stated is the most popular view of the origin of viruses but there is at least one other interesting idea. Cellular life may have arisen as "parasites" upon something called RNA-world, a whole ecosystem acting as one big organism. Viruses might be the remnants of the RNA-world "host," now parasitizing the former cellular parasites.

[King Prout]

entirely possible, and fits in with my suspicion that common descent from ONE common cellular organism might be erroneous.

[King Prout]

and, of course, it may be both

some viruses might be remnants of RNA World
other viruses might be escapees from cellular DNA/RNA