Malicious code is a computer program put on your computer either without your knowledge (such as when you browse an infected website) or which you are tricked into installing.
Such code is called “malicious” because its creators want to use it to annoy, scam, or harm you or others, either through:
Malicious code can take many forms, such as:
These attempt to run on your computer when you visit an infected website. Most modern browsers will give you a warning that a website wants to run a script when it happens. There are in fact many legitimate reasons a website may try to run a script on your computer – for instance, some websites will try to put a little file on your computer that remembers your details for your next visit (such a file is called a “cookie”) so you do not have to enter them again, so it can be hard to tell when a script is malicious.
These are a kind of virus, sent through emails and increasingly also through instant messaging. They are often hidden in an instant message or email in the form of an attachment, and the email will try to persuade you to open it. Some worms can mimic the email address of a friend in your contact list, to make you more likely to open it.
These programs are spread through network links between computers. They work by installing themselves on the infected computer and giving it instructions, usually to interfere with the computer’s effectiveness or damage it, and also to distribute itself to as many other computers as possible.
These malicious downloads include code hidden in other programs which the user actually wants to download. For instance:
This way the user will be tricked into downloading the program. Once installed, it is under the control of another person and your computer is then vulnerable to them if you have insufficient security.
The best way to avoid malicious code of all kinds when using Skype is to ALWAYS have up-to-date security software. There are many different kinds on the market, some of them free.
They can include the following features:
Anti-virus software – this checks your computer for signs of viral activity and scans it against a database run by the anti-virus company. If a match is found, the program discovered will be disabled or deleted.
Browsing security – this scans websites you browse to and checks whether they are legitimate. If not, you will be advised of any problems. Additionally, scripts such as cookies cannot be run or downloaded without your express permission.
Firewall – this feature protects your computer from intrusion from the network. Only trusted connections will be made between your computer and the network.
To learn more about your online security, safety and privacy, visit our security center.