If you come up with a blank stare when reading the words "DRM", or "rootkit", the following post may not be for you. If you are a concerned customer and value freedom, I suggest you keep reading.
Everyone knows record publishers have been pulling all kinds of strings to keep their CD's from being copied and pirated. To a certain level, I agree that no one benefits from listening to copied audio CD's, however I believe that most people will still go out and buy the original CD if they like the work and artists featured on it. A nice cover, extended leaflets and such just provide more incentive to do so. What I hate is people telling me what I can or can't do with goods I purchase. It has the same reaction on me as saying "you have to...". I don't have to do anything, period.
Likewise, if I buy a brand new audio CD and want to listen to it in my car, I should be able to do so. If I want to listen to it on my computer, I don't want to install extra software, players or listen to crippled audio tracks. It's my CD, so I decide what to do with it.
Enough for the subjective ranting, off to the technical side of things. DRM is a tool that prevents (or limits) the things you can do with you recently purchased CD. It won't prevent you from smashing it up, using it as a frisbee, or having your dog chew on it. I will however attempt to only play it on one cd player, prevent you from copying it, or even access the data on it without using vendor approved software. So much for a short intro on DRM. If you want to know more, check out wikipedia on DRM, or the collection of links and articles at EFF on DRM.
Rootkits... Usually connected to "evil", rootkits are receiving an increasing attention in the media, although most non-techies haven't picked up on them yet. A rootkit is software that will hide certain things from the user and the system itself. It's often used to install and hide malware, spy or adware onto a system. It's also used to create and maintain backdoors into computers without the knowledge from the owner. In short : rootkits hide things. Things that are hidden from you (the user/owner) make it hard to remove, or even analyse the possible implications. Does that explain in very simple wording what rootkits are? More (technical and specific) information can be found at Rootkits (wikipedia) or rootkit.com.
So... where were we? Aha, yes, rootkits and DRM. Let's just combine the two, will we? You unsuspectedly pop your newly purchased audio CD into the CD player of your computer - you are reading this on your computer, right? - and an installer screen pops up. You click next and get the legal mumbo jumbo, next, next, next, back, up, next, cancel, next, OK. Now that was easy, wasn't it? Where's my damn music?!
Aaah... reboot, and there it is : a crappy player interface giving you access to your beloved new audiotracks. Wait, why can't I use my personal favorite audio player? Let's see... it doesn't even find the data on the CD, hm... Ah well, I gotta run so lets quickly make a copy of this CD so I can listen to it in my car. A place that's usually lethal for CD's, mind I say. What? No copy either? WTF!
You rip the CD from the player, throw it back in the jewelcase and head off to do more important things. When you get back home, you try using your own favorite music player again, and you fail. A copy still ain't possible, so you get annoyed and uninstall whatever crap was installed on your computer in the first place. Reboot, done! Enough of it, and that CD will probably end up somewhere at the bottom of your pile, because it could have been so much, but is so little.
End of story? Not if that was a Sony/BMG DRM CD, my friend. When you uninstall, the rootkit used to hide the DRM from the user, remains installed. And that same rootkit can - and will - be abused by other programs like spy and adware or viruses to hide themselves from the system. An up to date virusscanner? No good, as the virus is hidden from the system itself. Can you remove the rootkit yourself? Yes, but only if you ask the Sony/BMG techies for instructions*. (updated on 02/11/2005 to reflect new link)
Also see Removing Sony's CD 'rootkit' kills Windows (The Register) and Mark's Sysinternals Blog : Sony, Rootkits and Digital Rights Management Gone Too Far.