Here are answers to some common questions about viruses, worms, and
Trojan horses.
What is a virus?
A virus is a program that replicates itself. It spreads by making
copies of itself on a computer or by inserting computer code into
program or operating system files. Viruses don't always damage files or
computers, but they usually affect a computer's performance and
stability. For a virus to infect a computer or to spread, you usually
have to do something, such as open an infected e-mail attachment.
Are all viruses harmful?
Yes, to varying degrees. Virus damage can range from slowing computer
performance to a loss of information and programs. In the worst case,
viruses delete or modify information and programs on your computer.
Some e-mail viruses send confidential information in messages when
spreading. Even when a virus is not directly damaging information, the
process of replication can slow your computer and Internet connection.
What is a worm?
A worm is computer code that spreads without user interaction. Most
worms begin as e-mail attachments that infect a computer when they're
opened. The worm scans the infected computer for files, such as address
books, or temporary webpages, that contain e-mail addresses. The worm
uses the addresses to send infected e-mail, and often mimics (or
spoofs) the "From" addresses in subsequent e-mail messages so that
those infected messages appear to be from someone you know. Worms then
spread automatically through e-mail, networks, or operating system
vulnerabilities, often overwhelming those systems before the cause is
known. Worms aren't always destructive to computers, but they usually
cause computer and network performance and stability problems.
What is a Trojan horse?
A Trojan horse is a malicious software program that hides inside other
programs. It enters a computer hidden inside a legitimate program, such
as a screen saver. It then puts code into the operating system, which
enables a hacker to access the infected computer. Trojan horses do not
usually spread by themselves; they are spread by viruses, worms, or
downloaded software.
What is a blended threat?
A blended threat is a combination of some or all of the malicious
programs discussed in the sections above. Blended threats often begin
when someone interacts with a virus (such as opening an unsafe e-mail
attachment). The virus automatically propagates using worm behavior,
and then installs a Trojan horse on the infected computer.
How do I prevent viruses?
Install an antivirus program. To be most effective, an antivirus
program should always be turned on, should scan incoming e-mail, and
should scan file access.
How do I know if my computer has a virus?
There is no single indicator of a virus infection, but some of the
more common effects include poor computer performance, pop-up ads
displaying (even when you have turned on a pop-up blocker or
disconnected from the Internet).
How do I check for and remove viruses?
To check for viruses and remove them from your computer, you need to
run antivirus software.
How to help prevent computer viruses
Nothing can guarantee the security of your computer 100 percent.
You can continue to improve your computer's security and decrease the
possibility of infection by using a firewall, keeping your system
up-to-date, maintaining a current antivirus software subscription, and
following a few best practices.
Tip: Because no security method is guaranteed, it's important to back
up critical files on a regular basis before you encounter a virus or
other problems.
Steps to help avoid viruses:
1.
Use an Internet firewall (Note: Windows XP with SP2 has a firewall
already built-in and turned on by default).
2.
Visit Microsoft Update and turn on Automatic Updates.
3.
Subscribe to industry standard antivirus software, such as Windows
Live OneCare and keep it current.
4.
Never open an e-mail attachment from someone you don't know.
5.
Avoid opening an e-mail attachment from someone you know, unless you
know exactly what the attachment is. The sender may be unaware that it
contains a virus.
What about spyware?
Although spyware programs are different from viruses, some can behave
like viruses and pose similar and other risks. Visit our spyware page
to learn more and to install Windows Defender at no charge.
Worm__elbasuer__WormA self-replicating program, similar to a virus. A
worm can make it possible for a malicious user to take over your
computer or can send out enough copies of itself to cause your computer
or a web or network server to stop responding. Virus__elbasuer__VirusA
program that attempts to spread from computer to computer and either
cause damage (by erasing or corrupting data) or annoy users (by
printing messages or altering what is displayed on the screen).
How can I tell if my computer has a virus?
If you can answer "yes" to any of the following questions, your
computer might have a virus.
Is your computer running very slowly? A common symptom of a virus is
much slower than normal computer performance. However, there can be
other reasons for slow performance, including a hard disk that needs
defragmenting, a computer that needs more memory (RAM), or the
existence of spyware or adware. For more information about spyware, see
How to tell if your computer is infected with spyware.
Are you getting unexpected messages, or are programs starting
automatically? Some viruses can cause damage to Windows or some of your
programs. The results of this damage might include messages appearing
unexpectedly, programs starting or closing automatically, or Windows
shutting down suddenly.
Is your modem or hard disk working overtime? An e-mail virus works by
sending many copies of itself by e-mail. One indicator of this is
that the activity light on your broadband or external modem is
constantly lit; another is the sound of your computer's hard disk
continually working. These are not always symptoms of a computer virus,
but when combined with other problems, can indicate a virus infection.
To check for viruses, scan your computer with an antivirus program. New
viruses appear every day, so keeping your antivirus program updated is
important. For more information about computer security, go to the
Security at Home page on the Microsoft website.
Signs of viruses: Are you infected?
After you open and run an infected program or attachment on your
computer, you might not realize that you've introduced a virus until
you notice something isn't quite right.
Here are a few primary indicators that your computer might be infected:
· Your computer runs more slowly than normal
· Your computer stops responding or locks up often
· Your computer crashes and restarts every few minutes
· Your computer restarts on its own and then fails to run normally
· Applications on your computer don't work correctly
· Disks or disk drives are inaccessible
· You can't print correctly
· You see unusual error messages
· You see distorted menus and dialog boxes
These are common signs of infection-but they might also indicate
hardware or software problems that have nothing to do with a virus.
Unless you run the Microsoft Malicious Software Removal Tool and
install industry-standard, up-to-date antivirus software on your
computer, there is no way to be certain if your computer is infected
with a virus or not. If you don't have current antivirus software
installed or if you're interested in installing a different brand, you
can try Windows Live OneCare free for 90 days or visit our Security
software downloads page for software from other companies.
Tip: Beware of messages warning you that you sent e-mail that contained
a virus. This can indicate that the virus has listed your e-mail
address as the sender of tainted e-mail. This does not necessarily mean
you have a virus. Some viruses have the ability to forge e-mail
addresses.
Articles taken from Microsoft.com
