Trojans

When spending time online you can often be bombarded with requests for you to download files such as desktop wallpapers, screensavers and widgets. However, if you decide to download anything such as pictures or files you could be downloading a trojan.

What is a trojan

A trojan, as the name suggests, is a malicious computer programme pretending to be something it’s not. A trojan will try to trick you into entering your personal details online.

A trojan can cause different levels of harm to your computer for example:

Erase or overwrite data on your computer
Record keystrokes to get your personal information
De-activate your firewall and your anti-virus software
Install other viruses

Since trojans come in so many different forms there is no one foolproof way of getting rid of them and they can be very hard to remove. Using anti-virus software and ensuring it's kept up to date is the best defence against trojans.

How to recognise a trojan

Some Trojans are invisible, but if your computer is running slowly it could be a sign that something is wrong.

Some trojans change your home page or toolbars; others display a dialogue box when you visit certain websites such as online banking sites. The dialogue box pops up in front of the website, asking you to enter your sign in details.

It could look like you are signing in to a legitimate site, when in fact you could be sending your confidential information to the fraudsters.

Remember, we never ask for your sign in details in a pop-up window or dialogue box. This could also be part of an email scam.

How to avoid trojans

If you are going to download a file try to make sure it is from a legitimate source
Scan attachments you receive by email before downloading
Use anti-virus software on your computer

High Profile trojans

There have been many notorious trojan viruses over the years:

ProRat allowed logging keystrokes, stealing passwords and gave full control over files amongst other things
Spy Sheriff disguised itself as an anti spyware programme then interfered with internet connectivity and caused computers to crash
Zlob trojan installed adware on users computers bombarding them with pop up ads