Depending on just how difficult of a world we're playing in, I've seen this go down in three basic ways.
Big Happy Family Worlds: Corps share lots of data fairly freely. They keep secrets, sure, but "common" data like criminal, personnel and medical files are easily accessible. These are nightmare worlds for Runners, since they can't play off Corp A against Corp B when it comes to establishing credentials, such data is freely available with the touch of a few keys.
Modern World Different Reasons: Corps share some information freely, but it's typically incomplete thanks to the corp's natural need for secrecy and sometimes outright stubbornness to give away information. There work a lot like it is today for different reasons. The local cops will have your criminal record, but not your medical ones and the hospital won't have a clue you're wanted in 5 states. Corp A may be willing to share information on personnel files, but not medical, or give up half your medical records without having your name attached to it.
Like I'd Tell You Worlds: Corps won't give up anything but scant information on anything to each other and that's only every fifth thursday of a month ending in "Q." If your ID has medical information from the Azzies and the cops are KE the odds of them being able to actually verify it are so remote you'll be old a grey before the Azzies even bother to reply with "we don't share that sort of thing." When it comes to ID and security checks, these are runner paradises.
In any of the worlds, all you really need to get through a security check is a good reason to have what you have, it's just a matter of how good it has to be since the databases get smaller and smaller from world to world. In the first, you'd need a set of top notch fakes from several places, in the last, you'd just need two or three fair ones indicating you work for different corporations and just do a little homework on who own the security firm you're against.