Using little more than a Web search engine and some simple software, a computer-savvy criminal or terrorist could easily leap beyond the boundaries of cyberspace to wreak havoc in the physical world, a team of Internet security researchers has concluded.

Automated order forms on the Web could be exploited to send tens of thousands of unwanted catalogs to a business or an individual, which could also paralyze the local post office.

The researchers suggested several methods to deter the attacks.