The rarely-used Messenger Service -- not to be confused with the Redmond, Wash. software vendor's Windows XP instant messaging client of the same name -- is intended to exchange "net send" and "Alerter" service messages between computers. Those can include updates from print jobs, a broadcast announcement by a system admin, or an alert following the activation of an uninterruptible power supply.
For that reason, the Messenger Service (which also relies on Remote Procedure Call services, or RPC) has been enabled by default on Windows operating systems since the mid-1990s, and launches automatically when a user boots up his or her personal computer. In its default configuration, Microsoft Windows also opens the NetBIOS TCP ports necessary to receive messages.
While it has provided instructions for users to disable the service on their own, Microsoft has said in the past that if turned off or blocked, applications that depend on the service could malfunction.
But last year, some ISPs, like AT&T Broadband and America Online, took the initiative to block the open ports on their subscribers computers. That's because spammers have taken advantage of the existence and accessibility of RPC and most users' open ports to send deluges of spam.
Making the problem more frustrating for end-users is that the recipient of NetBIOS messages (either legitimate or spammed) sees a dialog box that bears the title "Messenger Service." That bears a similarity to Microsoft's Windows Messenger IM client, which has led some users to wrongly conclude they were being spammed from the company's IM network.
Spokespeople from Microsoft's MSN service said last year that it would look into the matter, and that abusers of the service weren't actually capable of harming users' computers -- just of being annoying.
That changed in recent weeks, however. A virus, which some consultants dubbed the "Son of MSBlaster," has been circulating that takes advantage of a flaw in the service that causes Windows-based computers to crash. The service also created a hole that allowed for another vulnerability -- a buffer overrun flaw that could throw a machine at the mercy of a malicious user.
In response to the lingering privacy concerns and more recent security worries, AOL this month began implementing a script that deactivates the service entirely -- rather than simply blocking the ports, as it had attempted last year. The script runs when users log on to its service.
Microsoft said this week that it, too, now has plans to switch off the service as well.
Company executives announced the deactivation at the Microsoft Professional Developer's Conference on Tuesday. Specifically, Microsoft opted to turn off the services in Windows XP Service Pack 2, which is due in the first half of 2004.
Microsoft executives also said the company would activate Internet Connection Firewall (ICF) by default on XP boxes. ICF, a firewall built into XP, is normally turned off by default. Security experts said ICF could have blocked MSBlaster if it had been enabled.
Turning on ICF demonstrates a proactive approach to securing the desktop, said Gartner security analyst John Pescatore.
"Microsoft is definitely doing the right thing, and should do much, much more of it," Pescatore told our colleagues at internetnews.com. "One of the fundamental principles of security is 'Deny everything except that which is expressly permitted.' That translates to having all dangerous services (like Messenger) off by default and requiring the user to take explicit actions to choose to enable those dangerous services."
Microsoft, he added, is trying to break a lifetime habit.
"In desktop products they have had a corporate blind spot in the past -- Microsoft became the world's biggest software company by putting all the control in the hands of the PC user," Pescatore said. "They didn't consider safety a key requirement -- making Messenger and other things (like telnet or FTP services and the like) off by default is another important step."
Microsoft, of course, also is busily working to make good on its company-wide Trustworthy Computing pledge to stave off security problems by minimizing vulnerabilities.
The disabling of the Messenger Service comes amid proclamations from company executives that Microsoft is looking at ways to fortify the security of Windows in the face of computer viruses, worms and hackers.
In addition to terminating the Messenger Service, Microsoft said it would roll out a new API that makes the RPC services more secure.
Christopher Saunders is managing editor of InstantMessagingPlanet.com. internetnews.com assistant editor Clint Boulton is contributed to this story.