I have a legal CD of MS office 2007, I try make a backup copy CD of this.
In mac, with Disco, the burner say me, this CD are encryption.
In linux, with brasero, read and read many minutes but don't completed the copy of information.
To save a step of creating an ISO backup, the ISO for most Office versions are available from the microsoft site. Here's one that seems to allow a download if you have your office product key: