[an error occurred while processing this directive]
BBC News
watch One-Minute World News
Last Updated: Wednesday, 1 September, 2004, 15:42 GMT 16:42 UK
Zombie PC
Computer servers
Is your computer slavishly following orders from a remote master?
Have you ever suspected your PC of doing stuff behind your back, talking to people it should not? Is it leading a double life?

It is tempting to think your "personal computer" should obey only your instructions. It should do exactly what you want it to, not what anyone else does, surely...

But there are many more ways into your computer than just the keyboard and mouse.

Most importantly, there is your internet connection. This is divided into thousands of ports - in effect, doorways to your PC.

There is one for e-mail, one for your browser, and about 65,000 others handling more boring, day-to-day stuff.

And with the advent of broadband and "always on" network connections, they can get very busy indeed.


It is through these ports that attacks are made against your PC.

Protecting it should be those firewalls that Click Online is always harping on about. They are the equivalent of guards, deciding who to let in - and what stuff to let back out of your computer.

If you do not have a firewall that is correctly configured, or even turned on, you could be allowing malicious programmes to run on your computer.

This malicious kind of software - or malware - might not actually do much at all.

It probably will not go berserk and crash your computer, or wipe your hard drive. It may just sit there, listening, waiting for further instructions to come in on one of those unguarded ports - until the inevitable happens.

It receives remote orders, which it immediately obeys. In other words, it has become what we call in the trade a zombie.

Armies for hire

An average zombie PC looks like any regular computer: it doesn't eat flesh, groan or have aspirations to appear in a Michael Jackson video.

But while you go about your business, your machine is slavishly following orders from a remote master... sending out spam worldwide, or trying to bring down websites.

Detective Inspector Chris Simpson
Organised crime groups may be trying to advertise illegal services
Detective Inspector Chris Simpson

One zombie pc doing this on its own would be bad enough. But there are hundreds of thousands of them, all working together in armies called botnets.

These can send out billions of spam e-mails: in fact 70 per cent of all spam is generated by botnets.

As Google and Microsoft recently found out, the botnets can also bring down websites - by bombarding them with thousands of requests every second.

These botnets are now up for hire. People with the right kind of money and contacts can rent such services to do their dirty work. But who would want to rent them and why?

To find out, we spoke to Detective Inspector Chris Simpson from Scotland Yard's computer crimes unit, and Paul Wood from internet security experts MessageLabs.

You can watch the interview - which also explains steps you can take if you are affected - by clicking the video link in the box above.

Click Online is broadcast on BBC News 24: Saturday at 0745, 2030, Sunday at 0430, 0645 and 1630, Monday at 0030. Also BBC Two: Saturday at 0745 and BBC One: Sunday at 0645. Also BBC World.

Other items in this programme were:

Home PCs hijacked to spread spam
03 Aug 04  |  Technology
New virus exploits MyDoom success
28 Jul 04  |  Technology
Parents 'underestimate' net risks
20 Jul 04  |  Technology
Spam reveals its darker side
14 Jul 04  |  Technology


News Front Page | Africa | Americas | Asia-Pacific | Europe | Middle East | South Asia
UK | Business | Entertainment | Science/Nature | Technology | Health
Have Your Say | In Pictures | Week at a Glance | Country Profiles | In Depth | Programmes
Americas Africa Europe Middle East South Asia Asia Pacific