Using an instant messaging (IM) program — such as Windows Live Messenger (formerly MSN Messenger), Windows Messenger, AOL Instant Messenger, Yahoo Messenger or others — you and a friend can type messages to each other and see the messages almost immediately.
Because IM is so popular, virus writers can use it to spread malicious programs.
Understanding IM viruses
Like email viruses, instant message viruses are malicious programs that are designed to travel through IM.
These viruses are spread, in most cases, when a person clicks a link or opens an infected file that was sent in an instant message that appeared to come from a friend.
When you open one of these files, your computer can become infected with a virus. Because of the virus, your computer may slow down or stop responding, or you may not notice any change at all.
But the virus might have installed a covert program on your computer that could damage software, hardware or important files, and that could contain spyware, which can track information entered on the computer.
A computer infected by a virus may continue to spread the infection by sending copies of the virus to everyone on your IM contact list — that is, the collection of IM names that you can store in your IM program.
5 steps to help avoid IM viruses
As with most threats on the Internet, you can help keep yourself safe by taking basic precautions. If you know how to avoid email viruses, you'll already be familiar with many of these steps.
- Be careful with links and files in IM. Never click a link or open, accept or download a file in IM from someone you don't know. If the link or file is in an IM from someone you do know, don't click the link or open the file unless you know what the link or file is and you were expecting it. Contact the sender by email, phone or some other method to confirm that what he or she sent was not a virus.
- Update your Windows software. Visit Microsoft Update to scan your computer and install any high-priority updates that are offered to you. If you use automatic updating, the updates are delivered to you when they are released, but you have to make sure you install them.
- Make sure you're using an updated version of your IM software. Using the most up-to-date version of your IM software can better protect your computer against viruses and spyware. If you're using MSN Messenger, upgrade to Windows Live Messenger, which will block attachments that might contain malware and allow you to scan attachments for viruses.
- Use antivirus and antispyware software and keep it updated. Antivirus and antispyware software, such as Microsoft Security Essentials, can help to detect and remove malicious programs from your computer, but only if you keep the software current. Microsoft Security Essentials works with Microsoft Update. Windows Defender will also help defend your computer against spyware. Windows Defender is part of Windows Vista and Windows 7. If you install Microsoft Security Essentials, it will automatically disable Windows Defender. This is because Microsoft Security Essentials provides real-time protection that guards against viruses, spyware and other malicious software while Windows Defender only helps protect against spyware and potentially unwanted software.
- Run your computer as a standard user, not an administrator. Windows Vista and Windows 7 both include User Account Control, a feature that lets you run your computer as a standard user, while also enjoying the benefits of an administrator when you need them. This helps you avoid viruses and other unwanted software.