FOXNews.com reports that hackers were able to alter a portable traffic sign in Austin, Texas to read, "Zombies Ahead."

The hack occurred during the early hours of Jan. 19, but reverted back to the original message within hours. While it may seem like a harmless prank, tampering with portable road signs is illegal. It's considered a misdemeanor in Texas, with penalties ranging from fines to potential jail time.

Computerworld blogger Michael Farnum says the problem lies with default passwords in that they are rarely changed. Farnum doubts anything will be done by manufacturers to make signs more secure because it is a low-risk problem.

"Of course, if someone gets hurt or killed because of this and families sue, then things will change. But like always, it takes a serious incident to get anyone to do anything."