This information provides an introduction to viruses and ways to avoid them.
frequently asked questions
- what is a virus?
- what do viruses do?
- what is a worm?
- what is a horse Trojan virus?
- Can I get a virus by reading my email messages?
- How can I prevent an email virus infection?
- What are some general tips to avoid viruses and reduce their impact?
for more information
us-cert offers many resources to help you create a more secure home computing environment. These documents may be of particular interest if you have questions about viruses and Trojans:
- Understanding antivirus software
- Caution with email attachments
- Good security habits
- Recovering from a Trojan or virus
frequently asked questions
what is a virus?a computer virus is a program that spreads by first infecting files or system areas of a computer’s hard drive or network router and then making copies of itself same. some viruses are harmless, some can damage data files, and some can destroy files. Viruses used to spread when people shared floppy disks and other portable media, now viruses spread primarily through email messages.
Unlike worms, viruses often require some kind of user action (for example, opening an email attachment or visiting a malicious web page) to spread.
What do viruses do?A virus is simply a computer program: it can do anything that any other program running on your computer can do. some viruses are designed to deliberately damage files, and others can simply spread to other computers.
what is a worm?a worm is a type of virus that can spread without human interaction. Worms often spread from one computer to another, consuming valuable memory and network bandwidth, which can cause a computer to stop responding. worms can also allow attackers to gain access to your computer remotely.
what is a trojan horse?a trojan horse is a computer program that hides a virus or other potentially harmful program. A Trojan horse can be a program that pretends to perform an action when, in fact, it is performing a malicious action on your computer. Trojan horses can be included in software you download for free or as attachments in email messages.
Can I get a virus from reading my emails? Most viruses, Trojans, and worms are triggered when you open an attachment or click on a link in an email message. email. if your email client allows scripting, then it’s possible to get a virus just by opening a message. it is better to limit what html is available in your emails. the safest way to view email messages is in plain text.
How can I prevent an email virus infection? Most users get viruses by opening and executing unknown email attachments. never open anything attached to an email message unless you know the contents of the file. If you receive an attachment from a familiar email address but didn’t expect anything, you should contact the sender before opening the attachment. If you receive a message with an attachment and you don’t recognize the sender, you should delete the message.
Selecting the option to view your email messages in plain text, not html, will also help you avoid a virus.
What are some tips to avoid viruses and reduce their impact?
- Install antivirus software from a trusted vendor. update and use it regularly.
- In addition to checking for viruses regularly, install an “on-access” scanner (included in most antivirus software packages) and set it to start every time you turn on your computer. this will protect your system by checking for viruses every time you run an executable file.
- use a virus scan before opening any new programs or files that may contain executable code. this includes packaged software you buy from the store, as well as any programs you may download from the Internet.
- If you are a member of an online community or chat room, be very careful when accepting files or making click links you find or that people send you within the community.
- be sure to back up your data (documents, bookmarks files, important emails, etc.) to a disk so that, in the event of a virus, infection, you do not lose valuable work.