Threats to Computer Security (Virus)
The words Trojan,
worm and virus are often used interchangeably, though they are
not exactly the same thing. Viruses, worms and Trojan horses are all malicious
programs that can cause damage to our computer.
Virus
It
is a malicious computer program and attaches itself to a program or file,
enabling it to spread from one computer to another. Like a human virus, some
computer viruses may cause only mildly annoying effects while others can damage
your hardware, software or files. Almost all viruses are attached to an
executable file, which means the virus may exist on your computer but it
actually cannot infect your computer unless
you run or open the malicious program. It
is important to note that a virus cannot be spread without a human action (such
as running an infected program) to keep it going. As a virus is spread by human
action people will unknowingly continue the spread of a computer virus by
sharing infecting files or sending emails with viruses as attachments in the
email.
Worm
It
is similar to a virus by design and is considered to be a sub-class of a virus.
Worms spread
from computer to computer, but, unlike a virus, it has the capability to travel without any human action. A worm takes advantage of file or information transport
features on your system, which is what allows it to travel unaided. The biggest
danger with a worm is its capability to
replicate itself on your system, so rather
than your computer sending out a single worm, it could send out hundreds or
thousands of copies of itself, creating a huge devastating effect. One example
would be for a worm to send a copy of itself to everyone listed in your e-mail
address book. Then, the worm replicates and sends itself out to everyone listed
in each of the receiver’s address book, and the manifest continues on down the
line.
Due to the copying
nature of a worm and its capability to travel across networks, the end result
in most cases is that the worm consumes too much system memory (or network
bandwidth), causing Web servers, network servers and individual computers to
stop responding.
Trojan horse
It
is as tricky as the mythological Trojan horse it was named after. At first
glance it will appear to be useful software but will actually do damage once
installed or run on your computer. Those on the receiving end of a Trojan horse
are usually tricked into opening them because they appear to be receiving
legitimate software or files from a legitimate source. Some Trojans are designed to be more annoying
than malicious (like changing your desktop, adding silly active desktop icons)
or they can cause serious damage by deleting files and destroying information
on your system. Trojans are also known to
create a backdoor on your computer that gives
malicious users access to your system, possibly allowing confidential or
personal information to be compromised. Unlike viruses and worms, Trojans do not reproduce by
infecting other files; nor do they
self-replicate.
Blended Threats
A
blended threat is a more sophisticated attack that bundles some of the worst
aspects of viruses, worms, Trojan horses and malicious code into one single
threat. Blended threats can use server and Internet vulnerabilities to
initiate, then transmit and also spread an attack. Characteristics of blended
threats are that they cause harm to the infected system or network, they
propagate using multiple methods, the attack can come from multiple points, and
blended threats also exploit vulnerabilities. While a worm may travel and
spread through e-mail, a single blended threat could use multiple routes,
including e-mail, IRC and file-sharing networks. Blended threats are considered
to be the worst risk to security since the inception of viruses, as most
blended threats also require no human intervention to propagate.
Combating Viruses, Worms and Trojan Horses
The
first step in protecting your computer from any malicious programme is to
ensure that your operating system (OS) is up to date. Secondly, you need to
have anti-virus software installed on your system and ensure you download
updates frequently to ensure your software has the latest fixes for new
viruses, worms, and Trojan horses. Additionally, you want to make sure your
anti-virus program has the capability to scan e-mail and files as they are
downloaded from the Internet, and you also need to run full disk scans
periodically. This will help prevent malicious programs from even reaching your
computer.
Firewall
A
firewall is a system that prevents unauthorised use and access to your
computer. A firewall can be either hardware or software. Hardware firewalls
provide a strong degree of protection from most forms of attack coming from the
outside world and can be purchased as a stand-alone product or in broadband
routers. Unfortunately, when battling viruses, worms and Trojans, a hardware
firewall may be less effective than a software firewall, as it could possibly
ignore embedded worms in outgoing e-mails and see this as regular network
traffic.
For individual home
users, the most popular firewall choice is a software firewall. The downside to
software firewalls is that they will only protect the computer they are
installed on, not a network.
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