Security vendors are issuing warnings about a virulent new worm, which took down Ministry of Health systems for 15 days.

Conficker – also known as Downadup or Kido – is a uniquely pestilent species of worm, infecting PCs via the internet or “manually” via USB thumb drives. Once it has infected a computer, Conficker “phones home” to a malicious server, which delivers a payload of malware (which could be any malware, such as a programme that sniffs out personal details).