A new variant of the Bagle email worm is spreading rapidly across the internet today. Email filtering firm BlackSpider Technologies reports that it was blocking 2000 copies of Bagle-AT an hour since its first appearance earlier this morning.

Bagle-AT is one of three new variants of the long-running email worm series released over the last 24 hours but the only variant to cause a significant problem. Emails infected with Bagle-AT come with one of several executable attachments (COM, EXE, SCR) and attachment names such as Price or Joke. Typical subject lines of infected emails include 'Re: Hello' or 'Re: Thank you!'.

Like previous variants, Bagle-AT is also capable of copying itself into shared folders of infected machines, thereby allowing it to spread across file-sharing networks. Also in common with its siblings, Bagle-AT contains a backdoor that enables virus writers or their associates to control infected machines. The worm also tries to disable a range of security applications, along with any instances of the NetSky worm it finds on infected machines. Anti-virus vendors rate Bagle-AT as a medium to high risk threat.

Google-bashing worm makes modest debut

In other viral news, a new email worm which launches a denial of service attack from infected PCs against Microsoft, Google and the Hungarian Prime Minister's website is spreading (modestly) across the Internet. The Zafi-C worm is far less widespread than the earlier variants of the worm. Most AV vendors rate it as a low risk.

Nonetheless Windows users would be well advised to be on the look-out for emails with subject lines such as "Re: Hey buddy!" and "Re: very sick little girl!" that fit the profile of Zafi-infected emails. If users run the attached file, it can launch a distributed denial of service attack against the website of the newly-appointed Prime Minister of Hungary, the millionaire businessman Ferenc Gyurcsány, as well as attacking the websites of Google and Microsoft. All three of the targeted sites are readily available at the time of writing.

The previous version of the Zafi worm, Zafi-B, has continued to spread widely since June with a message calling for the death penalty to be introduced in Hungary.

All the email worms discussed above only infected Windows machines, as is the local custom. ®

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