Recently DDoS (distributed denial of service) attacks have become increasingly popular, with large companies such as PayPal, Hotmail and several high street banks having their websites taken offline.
DDoS attacks can now be illegally purchased online by companies wishing to cause disruption to their competitors’ websites and online services.
DoS (denial of service) attacks were historically an issue; they made multiple requests (enquiries) to a website in order to ‘overwhelm’ the servers eventually causing them to crash. These are relatively simple to block as the originating requests can be sourced and then blocked.
DDoS attacks are harder to resolve. They use Trojans to infect PCs around the world, and on instruction these PCs each make requests to a single website or online service. Due to the sheer number of PCs involved this means the attack can be catastrophic, and due to the PCs being distributed around the Internet, there is no single source and so the requests are not easily blocked.
It is very hard for a web server to differentiate between regular traffic and a PC working as part of a DDoS attack.
Users can protect their own PCs from these Trojans by using anti-virus software, but for the websites being targeted there is little protection and it can be an expensive task to resolve.
Quite literally a website can be taken offline for a few pounds, and unfortunately this is becoming far more common.