__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ TECHNICAL BULLETIN Spamming using the Windows Messenger Service October 29, 2002 24:00 GMT Number CIACTech03-001 ______________________________________________________________________________ PROBLEM: A spam engine has been released that uses the Windows Messenger Service (not the MSN Messenger instant messaging program) to send spam messages to users. The Messenger service is active on must Windows platforms. PLATFORM: Windows platforms with the Messenger service active. ABSTRACT: The Messenger service (not to be confused with MSN Messenger) is used by applications to send messages to the user and by system managers to send messages to users within a network. A spam (unauthorized commercial mail) engine has been devised that uses this service to send messages to systems that cause a dialog box to open on a user’s desktop. The dialog boxes open without any user interaction with the system. The Messenger service should not be turned off as many programs, such as antivirus scanners, use this service to send messages to the user. Messenger dialog boxes can only hold text, cannot have links to other websites, and cannot start applications. This spam starts with a connection to port 135 so sites with firewalls that block incoming connections to the Microsoft networking ports (135, 137-139, and 445) are immune from this spam. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/techbull/CIACTech03-001.shtml OTHER LINKS: CNN News article: http://www.cnn.com/2002/TECH/internet/10/21/ pop.upspam.ap/index.html Cnet News article: http://news.com.com/2100-1001-962483.html Wired News article: http://www.wired.com/news/technology/0,1282,55795,00.html ______________________________________________________________________________ It has been reported by online news services that a new spamming method and engine has been devised and is being made available over the Internet. The new method uses the Windows Messaging service, which should not be confused with MSN Messenger instant messaging, to send spam (unauthorized commercial mail) messages to computer systems. The Messenger service on Windows systems is provided for sending messages to the user of the system. The message window pops up in front of everything on a user’s desktop and displays the message to him. The message box will not go away until the user clicks Ok. The messenger service was designed to be used by application programs who need to send an alert to the user of the system and by system managers to send messages to everyone in a domain. It turns out that if a system is accessible from the Internet that someone can send a message to the Messenger service on a particular machine and that machine will display the message. The message can only be text as there are no provisions within the messaging service to send pictures, active links to websites, or to execute code as is done with e-mail generated spam. However, the message appears on a user’s system without any user intervention in front of whatever the user is working on. The user does not need to have an e-mail reader or a web browser open to receive and display these messages. Sites that have a firewall that blocks the Windows networking ports (135, 137-139, and 445) are already protected from this spam. This particular spam engine starts with a connection to port 135 rather than the NetBIOS ports (137-139 and 445) and then connects to a port above 1024 but future spam engines could use the NetBIOS ports as well. The Messenger service generally should not be disabled or shut down because different programs use it to pass messages to a user. System managers also use it to warn of impending network actions such as server shutdowns. It is possible to use the IP Filtering feature of Windows to block the incoming connections at the machine but the filter’s options are “Permit All” or “Permit Only ”. To make the filter work, you must use the “Permit Only ” option and supply the list of all allowed open ports. TCP Filtering is part of the Advanced Properties of the TCP/IP Protocol in the Networking control panel. Note also that blocking incoming connections to ports (TCP and UDP) 135, 137-139, and 445 at a machine may prevent that machine from participating in Windows Networking. We have seen one company (www.coffeecup.com) that is offering a filter for these ports that keeps the ports open for network communications but blocks the spam messages. ______________________________________________________________________________ CIAC, the Computer Incident Advisory Capability, is the computer security incident response team for the U.S. Department of Energy (DOE) and the emergency backup response team for the National Institutes of Health (NIH). CIAC is located at the Lawrence Livermore National Laboratory in Livermore, California. CIAC is also a founding member of FIRST, the Forum of Incident Response and Security Teams, a global organization established to foster cooperation and coordination among computer security teams worldwide. CIAC services are available to DOE, DOE contractors, and the NIH. CIAC can be contacted at: Voice: +1 925-422-8193 (7x24) FAX: +1 925-423-8002 STU-III: +1 925-423-2604 E-mail: ciac@ciac.org Previous CIAC notices, anti-virus software, and other information are available from the CIAC Computer Security Archive. World Wide Web: http://www.ciac.org/ Anonymous FTP: ftp.ciac.org PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing communities receive CIAC bulletins. If you are not part of these communities, please contact your agency's response team to report incidents. Your agency's team will coordinate with CIAC. The Forum of Incident Response and Security Teams (FIRST) is a world-wide organization. A list of FIRST member organizations and their constituencies can be obtained via WWW at http://www.first.org/. This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. 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