Zone Labs, makers of the popular ZoneAlarm firewall, is extending its security expertise to instant messaging with the release this week of IMsecure Pro, software designed to block invaders from the most widely-used messaging programs.

IMsecure Pro 1.0 runs on a desktop system and protects against inbound threats like malicious code and spam, says Frederick Felman, Zone Labs vice president of marketing. Users can also choose to block certain IM features, such as file transfers and voice and video chats. The program also supports encryption for messages sent between IMsecure users. It can even stop you from inadvertently releasing private data.

Available as a US$19.95 download from Zone Labs, the program includes one year of security updates. After that, the fee is $10 yearly. Zone Labs is also introducing a 15-day trial version of the Pro version and a bare-bones IMsecure 1.0 as a free download for personal and nonprofit use. Both programs run on all recent Windows operating systems.

IMsecure Pro applies Zone Labs' "guilty until proven innocent" security philosophy by blocking favorite hacker tricks like spam, IM-borne scripts, and buffer overflow attacks (such as was used by the Slammer worm). It also protects outbound data with 56-bit DES encryption when users at both ends are employing IMsecure Pro.

It's intended to thwart identity thieves who coerce people into revealing information, Felman said. "It's confidence fraud," he explains. The casual nature of instant messaging causes people to forget they don't really know the correspondent, he said. "And they give them more information than they should. MyVault reminds people that you shouldn't do that. If you start to type in certain information you've called confidential, it warns you and blocks it on the other side."

Spammers have clued into IM as a tool to gather data, Felman says; so IMSecure includes a Spam-Blocker function.

"They realize that mail names correspond with account names," and check for a valid e-mail address by sending an instant message, Felman says. Spam-Blocker keeps the unwelcome messages from appearing on your screen, protecting you not only from IM spam, but possibly from e-mail spam, too.

IMSecure Pro works with AOL Instant Messenger (AIM), Microsoft's MSN Messenger, and Yahoo Messenger, which, combined, are the choice of over 90 percent of IM users, according to Zone Labs. It also supports those IM programs when used through an aggregator application, such as Trillian. However, it does not support IM services other than those three, such as ICQ, even when it is running through an aggregator, said Felman.