Introducing - Computer worm

In computer terminology, a Worm is a self-replicating threat that travels
through a network and settles in a computer via a variety of online applications
like e-mails, chat clients, P2P clients, etc. A worm does not attach itself to any
program that explicitly needs to be executed for its spread. Instead, it travels
through networked applications and primarily replicates itself up to a point
where the network is clogged with its clones, preventing it from being used by
legitimate applications.

The different types of worms you could encounter are:



E-mail worm:

This type of worm uses e-mail as its vehicle. When an infected e-mail reaches
your inbox, it does nothing unless the e-mail is opened to be read. When you
open the mail, you may see an attachment or a link to a real or fictitious web site.
The moment you click on the link and visit the web site, the worm gets triggered.
Once activated, it starts searching your address book and sends e-mails to your
contacts. It can even fake the sender’s address, so that the recipient assumes that
the mail is not from someone he knows. Clearly, across an office network consisting
of tens or hundreds of users, the numbers of ficticious e-mails traversing the mail
servers grow exponentially over a short time. E-mail worms often bring down
mail servers and clog their functioning.

File sharing network worm:

This worm generally proliferates through a shared folder of a machine.
It creates a copy of itself and masks its intent by using a seemlingly harmless
and unassuming name. The moment you connect to a networking site like ‘kazaa.com’
and your sharing folder gets accessed, the copy of the worm moves from your computer
to other computers in the file sharing network. With millions of computers actively
being used to access files from peer-to-peer networks, these worms can proliferate
very quickly. Another popular type of worm is the instant messaging worm
(similar to the email worm, but uses an instant messenger service as its vehicle).

Trojan:

Trojans are malicious programs that pose as legitimate applications.
When users execute such programs, blissfully unaware of their real intent,
the host computer gets infected. Once on your computer, it may strike in a
variety of ways, ranging from capturing what you see on your screen to logging
what you type. The captured information is then sent to the author of that
malware through the Internet. You could therefore stand to lose precious data,
bank passwords and the like. The different types of Trojans include remote access
Trojans, where others can gain access to and even take over your machine,
data sending Trojans that scan your computer and send data to the author, and
destructive Trojans that simply delete files on the host computer. Trojans can also
infect your computer and you may face denial of service (unavailability of data).
Trojans even have the potential to counter anti-virus software by changing their
coding DNA (a process known as polymorphism), making it harder to detect.
Some Trojans are developed such that they will only be activated on particular
dates, or when certain pre-defined conditions are met by the computer.
These Trojans are known as ‘Time bombs’ and ‘Logic bombs’ respectively.
Spyware Like Trojans, Spyware is also a type of computer application, developed
with the intention of stealing information from your computer. These applications
can steal data including the history of web sites you have visited, passwords that
you have used to access online secure services, etc . However, unlike Trojans and
worms, spyware cannot replicate but it does exploit the host computer for
commercial gain. These include everything from throwing unsolicited
pop-up advertisements, capturing your web browser’s home page and
directing it elsewhere. This type of application cannot spread by itself,
therefore its efficacy depends solely on whether you choose to install the
software. Since users wouldn’t intentionally install applications that are
detrimental to their interest, spyware represents itself as a utility application,
for example, a web accelerator, a free image utility, etc. Spyware often piggy-backs
on to shareware applications found on download web sites or application CDs.

Adware:

Adware is more of an annoyance than a threat. Typically found in applications
downloaded from questionable web sites, it infects the host computer by
downloading and installing other advertising material and displaying it on
your computer via annoying popups that appear while you use Internet applications.
This is where adware generally gets confused with advertising-supported software.
The latter is not malicious and only displays an advertisement within the window of
the application program (such as trial or shareware versions of software). Adware,
on the other hand, displays advertisements randomly, often when you least expect it.

The last call:

This new breed of Internet threats may or may not be harmful to users,
but they do hamper the performance of computers. To protect computers
from today’s digital threats, an anti-virus program is a good place to start.
for application suites that specifically offer protection against all of these
threats and not just ones that offer plain vanilla virus protection. In today’s
world, data security requires blanket protection systems that do it all.
You can also install anti-spyware and adware application like NoAdware,
ErrorDoctor, Spynukke, AdAware, etc. Secondly, it is important to exercise
caution on what applications and fi les are downloaded. This includes your
mail attachments.
Chain mails with attachments (such as .exe, .com, .scr, .bat, or .pif),
download sites that contain links of questionable web sites, applications
that aren’t from trusted sources should all raise a user’s alarm bells.
Most of the time, the battle against malware can be won before
it even begins—all it takes is a bit of vigilance.