Recently, I began to receive spam messages that simply pop up on my computer screen. After a little research, I discovered that this spamming technique uses Windows built-in Messenger service, which sends messages in a broadcast across a network. The way to block these annoying messages is to disable the Messenger service. In Windows XP, you can do this through the Control Panel. Navigate to Administrative Tools | Services. Double-click on Messenger and click on Stop. Then set the Startup Type to Manual or Disable. Click on OK and the pop-up spam will be blocked.
Network administrators have used the Messenger service (not to be confused with the MSN Messenger instant-messaging clients) to broadcast notices to all network users, but these days theyre much more likely to use e-mail. On most networks, the Messenger service is simply not needed, and its certainly useless when your system is not connected to a network.
In Windows NT 4.0, 2000, and XP, the Messenger service receives messages from other computers on the network, typically transmitted using NET SEND at the command line. For example, the command NET SEND * Wanna buy a duck? sends the message Wanna buy a duck? to all users (see Figure 2). For more details on using this command, enter NET HELP SEND at any command prompt.
The type of spam described here subverts the same service, causing it to pop up unwanted commercial messages. Windows 95, 98, and Me do not have this problem, as they receive such Net messages only when the WinPopup applet is running.
If youre running Windows XP or 2000, the instructions above will turn Messenger off. With Windows NT 4.0, it may be difficult to locate the Services applet. In this case, launch Help, select Services in the index, and select enabling/disabling below Services. The resulting help topic provides a link that launches the Services applet.
If you dont want to disable the Messenger service, you can prevent its misuse by configuring your firewall to block inbound UDP and NetBIOS.