AT&T today announced a new managed security service, offering businesses large and small network-based protection from Web threats, including viruses, worms and other malware.

AT&T Web Security uses policy management to enable employers to filter and screen Web content and instant messaging that are an increasingly important part of doing business, said Stan Quintana, AT&T security services vice president. The service uses security built into different layers of the network to screen all non-encrypted HTTP traffic into and out of a business.

“Many corporations are starting to do business through the Web,” Quintana said. “As employees access sites, they are bringing back substantial numbers of infections, worms, malware, spyware and other things that cause considerable damage. A lot of companies are aware of this, the question is how do you take care of it and how do you do it on a cost-effective basis.”

AT&T Web Security enables employees to manage Web access down to the individual employee level and restrict access to some Web sites or content, using policy management. The service is billed on a per-seat basis and enables even small businesses to have more secure Web access, Quintana said, while saving the cost of hardware and software for companies thinking of providing their own security.

The Web Security is the latest in a series of managed security offerings that AT&T has announced over the last year. Earlier this month, rival Verizon Business announced new tools to help businesses ward off spyware and phishing attempts.

AT&T’s service monitors Web traffic at the network level or down to the individual PC, if preferred, using client software on the user’s PC. Customers get a Web-based portal for administration and reporting that includes customized alerts and automated reports. AT&T Web Security does near real-time scanning of requested sites and files and filters IMs as well.

Many of those sites don’t realize they contain spyware or malware,” Quintana said. “We can do content scanning and filtering for various types of anomalous behavior.”