Sophos has become the first security vendor to give a standard anti-virus client the ability to block a range of risky applications, including VoIP, instant messaging, and P2P programs.

The new feature comes in the form of a free signature upgrade to the company’s Anti-Virus 6.0 software, and can stop a named list of programs from running on any PC on which the software is installed.

Notable on this list are Skype and Google Talk, IM clients such as AIM, MSN Messenger, Windows Live and ICQ, and traditional "plague" applications such as the file-sharing BitTorrent.

Previously, companies wanting to block troublesome applications of this ilk would have had to buy special software to do the job, usually at considerable expense. This approach also beats network traffic filtering approaches because by simply stopping named executables from loading; it can also control software on machines taken out of the network.

"In consumer environments these are legitimate applications," said Sophos' Graham Cluley, referring to the inherent security risks posed by many of this class of unauthorised applications. "But for too long the lunatics have been running asylum... the users have been deciding what runs."

Once installed as a low-impact signature upgrade to the standard client, admins can set policies for applications using the same console used to manage the anti-virus client. "Clearly enterprises want to stop employees from running unauthorised programs that eat up bandwidth, violate security policies or result in data leakage," said Sophos CEO Steve Munford.

"Sophos gives companies the tools to combat a growing problem without having to roll out new software or learn how to use a new management console. Our goal is to provide enterprises with a single management console and universal client for both security and general desktop management."

Adding application control to standard anti-virus will be compelling for many corporates already using Sophos software. It costs nothing, and allows them to control the rising tide of unauthorised applications without having to buy a new security product to gain the feature. It will likely become a standard feature of many other security clients in the months ahead, undercutting the market for standalone application control software.

Even legitimate applications in this category - especially Skype - have become highly controversial in recent times, as the security implications of allowing them to run in an unmonitored way have dawned on admins. Only this week, Skype announced plans to offer a corporate-friendly version of its software to address these concerns.

Sophos Anti-Virus can be configured to allow applications such as Skype to run for users where it is judged to be of benefit, but now it will be at the admin’s discretion, and not the user’s.

The software is available for Windows 2000/XP from today from the Sophos website. New users can deploy the anti-virus client either with or without the application control feature.