A new Windows worm called Sober is starting to spread widely online. The virus is said to be multiplying because so many versions of Windows are vulnerable.
Many people are thought to be falling victim to this new virus because one version poses as an security update from anti-virus firms. It also tries to hide by using many different subject lines in both German and English and by changing the name of the payload holding the virus.
Other subject lines used by Sober try to trick people into opening the message by looking like a warning that they are sending out e-mail messages infected with a virus.
Sober also re-uses subject lines seen in older viruses but again tries to fool users by adding comments that make messages bearing them look harmless.
The virus travels with its own e-mail appliance so it can send itself to any addresses it picks up from computers it has infected.
Having spread widely in Germany, Sober is now starting to turn up in the UK, with Windows 2000, 95, 98, Me, NT, Server 2003, and XP all vulnerable to infection. Like many other e-mail viruses Sober must be opened and its attachment clicked on to cause infection.
Once installed it displays a false error message that can con people into thinking they have avoided infection. Hidden inside the body of the virus is text that praises the creator of the Sobig worm that in August became the fastest spreading worm ever.
Security firms urge people to keep their anti-virus software up to date and be wary of unsolicited or unexpected e-mail messages.