Security vendor FaceTime Communications has released the only security product on the market allowed to look at encrypted instant messages sent between Skype users.

The upgrade to the company's Greynet Enterprise Manager (GEM) detects harmful URLs within instant messages.

Instant messages are one way a hacker can lure victims to a harmful Web site. Through a compromised instant-messaging account, a hacker may have access to a person's contact list. Those contacts may think they are being sent a link by a friend, but fall victim to a social engineering trick that puts their PCs at risk.

FaceTime is the only company that has an agreement to develop security software with Skype, which is owned by eBay.

Skype revealed to FaceTime part of an API that lets the company's product detect URLs but doesn't let it see the actual text of the messages, said Nick Sears, FaceTime's vice president for Europe, the Middle East, and Africa.

FaceTime detects malicious URLs by comparing those sent in instant messages to a database of known malicious links, Sears said. If a bad one is detected, the user is sent a warning message.

One of the most popular VoIP applications, Skype is known for its simplicity, convenience, and function. But it has posed a concern to companies due to its use of encryption for voice conversations and instant messages.

Skype constantly updates the protocol to ensure privacy for its users, but Skype's stealth is worrisome for security-minded IT managers tasked with ensuring sensitive company data doesn't leave their networks.

A year ago FaceTime released its first product for Skype, FaceTime Internet Security Edition for Skype. The product controls who is allowed to use Skype, as well as finer-grained controls, such as whether a user can use Skype's chat function or send files.

The latest upgrade is part of GEM, which is available as an add-on to FaceTime's USG (Unified Security Gateway), an appliance for instant messaging and VoIP security. Pricing for USG plus GEM's new Skype feature is about $9,000 for 100 users per year, which includes maintenance, Sears said.

The new Skype feature is also available for FaceTime's IM Auditor, an instant messaging management appliance.

This story was updated on March 25, 2008