Last October, security researcher HD Moore's scanned about 3% of addressable Internet space looking for high-end videoconferencing systems--the type of systems present in many corporate boardrooms and meeting spaces.

The scan, which took about two hours using a handful of computers, discovered a quarter of a million systems that understood the H.323 protocol, widely used by Internet protocol (IP) communication systems. Using that list, Moore, the chief security officer for vulnerability-management firm Rapid7, used a module for the popular Metasploit framework to "dial" each server, connect long enough to grab the public handshake packets, and then dropped the connection.

"Any machine that accepted a call was set to autoanswer," Moore says. "It was fairly easy to figure out who was vulnerable, because if they weren't vulnerable, then they would not have picked up the call."

Using the information, Moore and Rapid7 CEO Mike Tuchen identified 5,000 videoconferencing systems that were set to automatically answer incoming calls, allowing a knowledgeable attacker to essentially gain a front-row seat inside corporate meetings. Videoconferencing systems that automatically answer incoming calls can be turned on externally by an attacker without attracting the attention of people in the boardroom. In tests on systems in Rapid7's lab, the researchers found that the system could listen into nearby conversations and record video of the surrounding environment--even read e-mail from a laptop screen and passwords off of a sticky note that was 20 feet away.

While the number of vulnerable systems may be small--about 150,000 across the Internet, Moore estimates--the technique returned an interesting set of targets, he says.

"What made this interesting is that you are only going to find places that can afford $25,000 videoconferencing systems, so it's a pretty self-selecting set of targets," Moore says.

The lion's share of the videoconferencing systems found by Moore's experiment were made by Polycom, a leading manufacturer of the systems that mostly ship with their autoanswering functionality enabled. Companies using equipment from other manufacturers likely turned on the feature to make videoconferencing as problem free as possible.

Yet using such systems securely requires only a few, if not always simple, steps, says Joshua Talbot, security intelligence manager at Symantec.