A new variant of the Sober email worm is spreading rapidly across the internet today. Sober-I (AKA Sober-J) worm is mass mailing worm which sends itself to email addresses harvested from an infected computer. It uses variety of subject lines, message bodies and file attachment names, both in English and in German. There are 150 variants the most common of which are explained here.

Opening unsolicited on a Windows PC results in infection. Mac and Linux boxes are immune. Sober-I is the latest in a series of email worms dating back to Autumn 2003 but the Windows community remains as vulnerable as ever to this kind of attack. Anti-virus firm McAfee reports that it has received approximately 100 reports of the virus being stopped or infecting users from the field, from both the virus itself as well as customer submissions. Most of these reports have arrived from Europe, with a majority coming from Germany. Security firms generally rate Sober as a medium risk nuisance.

Standard defence precautions against viral attacks apply: corporates should consider blocking executables at the gateway and update anti-virus signature definition files to detect the virus. Home users should also update anti-virus tools and resist the temptation to open suspicious-looking emails. ®

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