Possibly in some countries...
But at least in the US, it is a DMCA violation.
DMCA gets a little weird; Basically unless you're distributing it is a civil penalty (which, I could be wrong but would mean you'd get a Jury trial, even assuming it ever came up) and I doubt you would ever run into legal issues so long as you were only backing up for personal use.
It's where you get into distribution that anyone starts to care, and it's when you do distribution on a large scale that criminal penalties come into play.
However there may be countries where possession of an 'illegal number' or 'DRM Breaking software' is considered legal for personal use.