Messenger Service window that contains an Internet advertisement appears

You may receive an Internet advertisement in a Messenger service window. The advertisement contains text that is similar to the following text: These messages are also known as "messenger spam."

This issue may occur if you receive a net send message from someone who is using the Messenger service in Windows. The Messenger service is a Windows service that transmits net send messages and messages that are sent through the Alerter service between client computers and servers. For example, network administrators use Messenger service to send administrative alerts to network users. Windows and other software programs can also use the Messenger service. For example, Windows may use it to inform you when a print job is completed or when you lose power to your computer and switch to an uninterruptible power supply (UPS). Your antivirus program may use the Messenger service to send you notifications. The Messenger service is not related to your Web browser, e-mail program, Windows Messenger, or MSN Messenger. This issue may occur if the following conditions exist:

• The Messenger service is started.
• The Remote Procedure Call service is started.
• Inbound NetBIOS (NetBIOS over TCP/IP) and UDP broadcast traffic is turned on for your Internet connection.

To resolve this issue, install or turn on a firewall that blocks inbound NetBIOS and UDP broadcast traffic. The method that you use to resolve this issue depends on your operating system and how you connect to the Internet. The following sections provide examples of several different configurations and possible methods of resolution.

You connect to the Internet directly

If you use a single computer that is connected to the Internet directly (by using a cable modem, a DSL modem, or a dial-up modem, for example), install a firewall and block inbound NetBIOS and UDPbroadcast traffic on your computer.

You are running Windows XP

If you are running Windows XP and connect to the Internet directly (by using a cable modem, a DSL modem, or a dial-up modem, for example), install Windows XP Service Pack 1 (SP1) and turn on Internet Connection Firewall (ICF). By default, the installation of Windows XP SP1 permits Internet Connection Firewall (ICF) to block all incoming traffic (unicast, multicast, and broadcast). By default, if you have installed Windows XP Service Pack 2 (SP2), Windows Firewall (WF) is turned on.

For additional information about this change in ICF blocking behavior in Windows XP SP1, click the following article number to view the article in the Microsoft Knowledge Base: For additional information about how to obtain Windows XP SP1, click the following article number to view the article in the Microsoft Knowledge Base: For additional information about how to turn on ICF, click the following article number to view the article in the Microsoft Knowledge Base:

You are running Windows 2000

If you are running Windows 2000 and connect to the Internet directly (by using a cable modem, a DSL modem, or a dial-up modem, for example), obtain and install a third-party firewall product that blocks inbound NetBIOS and UDP broadcast traffic. For additional information about firewalls, visit the following Microsoft Web site:

You connect to the Internet through a small network that you manage

If your network uses connection sharing to provide Internet access to multiple computers, install or enable the firewall only on the shared Internet connection.

You are running Windows XP with Internet Connection Sharing

If you use Internet Connection Sharing in Windows XP to provide Internet access to multiple computers, install Windows XP SP1 on the Internet Connection Sharing host computer and turn on ICF only on the Internet Connection Sharing host computer.

You are running Windows with a hardware Internet Connection Sharing device

If you use a router or other hardware device to provide Internet access to multiple computers, configure the connection sharing device to block inbound NetBIOS and UDP broadcast traffic. Contact the manufacturer of your third-party connection sharing device for more information.

You connect to the Internet though a network that you do not manage

If you connect to the Internet by using a corporate network, or if your Internet service provider (ISP) uses a firewall, ask the network administrator to configure the firewall to block inbound NetBIOS and UDP traffic. Contact your network administrator or ISP for more information.

To work around this issue, turn off the Messenger service. To do this, follow these steps:

1. Click Start, and then click Control Panel (or point to Settings, and then click Control Panel).
2. Double-click Administrative Tools.
3. Double-click Services.
4. Double-click Messenger.
5. In the Startup type list, click Disabled.
6. Click Stop, and then click OK.

Note If the Messenger service is stopped, messages from the Alerter service (notifications from your antivirus software, for example) are not transmitted. If the Messenger service is turned off, any services that explicitly depend on the Messenger service do not start, and an error message is logged in the system event log. Therefore, Microsoft recommends that you install a firewall and configure it to block NetBIOS and RPC traffic instead of turning off the Messenger service.

The Messenger service uses UDP ports 135, 137, and 138; TCP ports 135, 139, and 445; and an ephemeral (that is, short-lived) port number greater than 1024.

Firewalls help prevent net send messages and help protect your computer from other malicious attacks over the Internet. These attacks can be designed to perform the following tasks:

• Access your private information
• Distribute software illegally by appropriating space on your hard disk

For additional information about this issue, visit the following Microsoft Web site: