Viruses and other Malware
A computer virus is code that can replicate. Viruses are usually designed to damage or delete information on the target machine, but can be little more than a piece of executable code that simply replicates itself.
Other damage that can result fom Malware are monitoring activity such as logging keystrokes or viewing someone's desktop, extracting financial and personal data, moving or destroying data including entire files.
These days the threats include DOS or Denial of Service attacks; where large numbers of controlled computer 'ping' or the target website or computer Even more worrisome is examples Fifth Domain Warfare such as the Stuxnet attack on the Iranian's Busheir nuclear reactor.
E-Mail Viruses -
to emails and
replicates by posting itself to names found in the
victim's e-mail address book.
A worm is any
self-replicating software that
inserts itself in a computer by exploiting vulnerabilities
in a system, invading the system one machine at a
A malicious or nuisance
masquerades as another type of programme, for example
a game or utility.
Once a Trojan is established there are numerous activities that can then be performed; spambotting, data theft, damage etc.
Named after the wooden horse given by the Athenians to the citizens of Troy but hiding several men who emerged at nightfall to open the city gates to allow the Greek army to enter.
Macro Virus -
This can only be
spread via applications
such as Word and Excel which have Macro capabilities.
Distribution can be via e-mail
attachments, from a
modified programme, a malicious cracker or social
engineer, as a macro.
Defences include firewalls, soft
and preferably hard
and anti virus software such as Kaspersky, Mcaffee and Norton.
A virus can be tranferred via removable media and in the early days almost all of the infections were carried about on floppy disks. Nowadays, emails and downloading software, videos and music are the common vectors.
Spyware and Adware programmes are not capable of reproduction and, strictly speaking are not viruses - even though they may be equally difficult to eradicate.
For the ordinary internet browser having a good virus installed is the most important protective measure, A hardware firewall is a feature of a broadband router and is effective but you can also invest in software firewall software for extra security. If you are a business with an internal network then you can also invest in a range of measures including boxes that check all devices on a network for vulnerabilities.