Let's look at some of the
possible security problems contained within your computer, the web browser
specifically. This section assumes you are using Microsoft's Internet Explorer,
but many of the points are generally applicable to other browsers such as
Netscape and Mozilla. Cookies
Cookies are small text files created on your computer (commonly
in the c:\documents and settings\(username)\cookies folder) by websites you have visited that enable these
sites to identify you and your computer, and customize their content the next
time you visit them.
For example, a site using cookies could be set up to greet
you by name on each successive visit after you provide it with
your information. To accomplish this, a cookie with your name and an identification number
would be saved on your hard drive and passed to the website each
time you visit it.
Cookies are also commonly used to identify users automatically for access
to secure portions of the site, or to automatically pre-fill login information. Cookies
are endemic to the Internet. Just about every major site uses them,
and many websites (notably Microsoft) will refuse you access to portions of their website
if you have cookies disabled on your browser. Their use does carry a
few security concerns however.
For one thing, cookies often contain personal information
that you have given previously to the website, such as bank card numbers in
the case of many online banking systems, names and IP addresses, and potentially
even credit card numbers.
using your computer could have your login information for a web-email service, to
use just one example, automatically filled in for them because a cookie exists
on your computer containing this information. While cookies are unavailable to remote
websites and to remote users unless the security of your system is already compromised,
they are available to anyone with access to your PC who cared to
browse the cookies folder.
Incidentally, they also give a pretty clear picture of your online
activities to anyone checking up on you. Many websites that contain advertising,
of tracking customer (or potential customer) activities. This is accomplished by means of
tracking, or 'third-party' cookies.
The idea of these is that
an advertising company will rent space on a website for its ads, and
the content from these ads comes from their own web servers, so when a surfer views
the website, he also views information from the ad company's servers, and can
thus receive a cookie from them without having deliberately visited their website. Assuming
the ad company has placed banner ads on several sites, they will
be able to track your surfing habits to a degree based on the exchange
of cookies between you and their ad-servers that occurs when you visit a
website they advertise on.
Many advertising companies partner with peer 2 peer
sharing software providers such as Kazaa or makers of other popular "free"
software in order to gain access to names and email addresses to match the
internet addresses they derive from cookies, enabling them to put a 'face' to
users they are tracking.