Someone has developed software to "hack into" RFID tags and change the data stored on them.

A German software consultant developed the software, called RFDump, and released it at the recent BlackHat Security Conference.

Forbes magazine had this report about how the hack would work:

"A would-be scofflaw heads into a grocery store where all the products have RFID tags on them. Rather than paying $7 for a bottle of shampoo, he'd rather pay $3. To make that happen, he whips out a PDA equipped with an RFID reader and scans the tag on the shampoo. He replaces that information with data from the tag on a $3 carton of milk and uploads it to the shampoo bottle tag. When he reaches the check-out stand--which just happens to be automated--he gets charged $3 instead of $7, with the store's computer systems none the wiser."

But, there's more to this story.

I first learned about this story via this post over at the MIT Technology Review blog. Now the really interesting point is in the comments section. A number of commenters suggest the tags are probably going to be read-only (versus read-write) and therefore could not be hacked. Anyone have additional thoughts on this point?

UPDATE AUGUST 6: Anders pointed me to a good collection of links he's assembled over at RFID Buzz.