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EXPOSURE

65,535—that identifies the type of service the connection is seeking. The IP address is like a phone number, and a port is akin to a telephone extension you read off to the switchboard operator so he can send your call to the right desk.

Port numbers are standardized and published online. E-mail software knows to connect to port 25 to send a message; Web browsers connect to port 80 to retrieve a website. If a connection on the specified port is refused, it's like an unanswered extension; the service you're looking for isn't available at that IP address.

Max was interested in port 5900—the standard port for a VNC server. He set his machines sweeping through broad swaths of Internet address space, sending to each a single sixty-four-byte synchronization packet that would test whether port 5900 was open for service.

The addresses that answered his sweep streamed into a PERL script Max wrote that connected to each machine and tried to log in through the RealVNC bug. If the exploit didn't work, the script would try some common passwords: “1234,”“vnc,” or an empty string.

If it got in, the program grabbed some preliminary information about the computer: the name of the machine and the resolution and color depth of the monitor. Max snubbed computers with low-quality displays, on the assumption that they were home PCs and not businesses. It was a high-speed operation: Max was running on five or six servers at once, each capable of zipping through a Class B network, over sixty-five thousand addresses, in a couple of seconds. His list of vulnerable VNC installations grew by about ten thousand every day.

The point-of-sale systems were needles in a massive haystack. He could spot some just from the name: “Aloha” meant the machine was likely an Aloha POS made by Atlanta-based Radiant Systems, his favorite target. “Maitre’D” was a competing product from Posera Software in Seattle. The rest of them took some guesswork. Any machine with a name like “Server,” “Admin,” or “Manager” needed a second look.

Slipping in over his VNC client, Max could see what was on the com-