https://en.wikipedia.org/wiki/Welchia
Welchia, also known as the "Nachi worm", is a computer worm that exploits a vulnerability in the Microsoft remote procedure call (RPC) service similar to the Blaster worm. However, unlike Blaster, it first searches for and deletes Blaster if it exists, then tries to download and install security patches from Microsoft that would prevent further infection by Blaster, so it is classified as a helpful worm. Welchia was successful in deleting Blaster, but Microsoft claimed that it was not always successful in applying their security patch.[
Woah, I've only ever seen 'retrovirus' in reference to things like "scientists find retrovirus in ice!" So I totally thought it meant retro virus. I was wrong lol
Truly ‘retro’ viruses are too cool to use the term! It’s such an annoying hipster vibe they give off
HIV is the most famous retrovirus. The reason it's hard to cure is basically once it goes from bloodstream to the host cells, it adds itself to the host DNA and RNA, then it just replicates with our cells and that our cell will produce more of it.