Trojans can try to spread themselves using your email address book which can be very embarrassing for you so don’t open anything you are not expecting.

Windows as well as Macs normally hides the last extension of a file which makes it hard to spot executable files. Trojans might stick .jpg in the title so the filename you see might be filename.jpg but the files is actually filename.jpg.exe. You can normally right click on the file to look at its properties and this will reveal the true identity.

Disable the preview mode in Outlook and other email programs.

But you, personally, need to act as the first line of defence.

August 2004

Masquerading as an order-acknowledgement, a Trojan was slipped into an unprotected system when you, quite responsibly, query the wrong order. The code in the Trojan then captures password and PINs for use by fraudsters. Query false orders on any credit card with the card issuer direct rather than the 'supplier'. It helps them track the fraud.

Denial of Service (DOS) attacks

This stop people using their system by blocking the channels with multiple emails. To achieve this, the attackers invade innocent users with a Trojan or Worm and then use their computer to block the target's service. This often involves using a Trojan to send a blizzard of emails.

Most DOS attacks exploit bugs in an operating system. When these are identified they are patched. Windows users should regularly visit Microsoft's Windows Update Site to ensure that they do not become an unwilling accomplice.