Viruses
Viruses are programs that have been written to copy their code into other programs, meaning they 'spread' by themselves. Viruses can affect your computer system in many different ways:
- Deleting and altering files
- Displaying unwanted sounds and messages (pop ups)
- Redirecting web links to web sites you don't intend to visit
- Copying themselves and using up resources on your computer system
There are many different ways in which a virus can find its way onto your computer system:
- Downloading movies/games from pirate websites
- Using infected CDs/USB flash drives
- Opening links in emails from untrustworthy sources
- Downloading infected files in email attachments
Trojan horse
This type of malicious software pretends to be a useful program while secretly performing another function, like spying on your activities. Examples of Trojans might be:
- 'Free' online games that you can download. You can play them for free but they may be tracking your activity.
- Browser 'helper' toolbars. These appear to add features to your web browser but in reality are usually tracking your online browsing habits.
- Display as antivirus software - the Trojan may download other malware onto your computer system.
Worms
Worms are a type of malicious software that target networks. Most worms are designed to decrease available bandwidth by copying themselves multiple times before moving from port to port on a network. This reduces the chances of legitimate traffic being able to move from system to system as the worm continually replicates itself across the network.
Sometimes worms also contain what is known as a ‘payload’. Payloads are additional actions that extend beyond constant copying and can include things like deleting important files, encrypting files and installing code that can give a hacker access to a computer system.
Hacking
When someone gains unauthorised access to a computer system, they are ‘hacking’. Hackers are at work on a daily basis and attack systems for a variety of reasons. Some hackers do so for fun, as they like to try to find security faults that exist on large commercial systems. People hacking for this reason will often notify organisations if they find security flaws.
Governments also employ staff to hack into systems owned by rival nations and for this reason there are now University courses on Ethical Hacking. These courses aim to teach students how to bypass systems in the interests of security.
There are malicious hackers or hacking groups who are motivated by financial, social or political reasons and will work tirelessly to attack systems and organisations of their choice.
Sometimes they will steal data or will be paid to hack into a system. On other occasions they publicise their hacking to deliver political or social messages. In the UK, hacking is an offence under the terms of the Computer Misuse Act.
