Security threats Toolkit

Sober worm clogs Hotmail connections

Published: 05 Dec 2005 09:00 GMT

The pesky Sober worm is to blame for disrupting email traffic between Comcast account holders and users of Microsoft-based email, Redmond said on Friday.

A variant of Sober known as Win32/Sober.Z@mm is pummelling servers at Hotmail and MSN with "unusually high mail load", causing delays in email delivery to Hotmail and MSN customers, said Brooke Richardson, MSN's lead product manager. Richardson also indicated that ISPs besides Comcast may be having problems directing email to Hotmail and MSN servers.

"We are working with Comcast and other ISPs to address [the] issues," Richardson said. "We're actively working to take the appropriate steps to remedy the situation as rapidly as possible. We sincerely apologize for any inconvenience."

Blog reports say that some Comcast subscribers, when sending email to a Hotmail or MSN account, have received an error message saying their message was not received. However, Microsoft says that all emails, while some may be delayed, are eventually getting through.

A Microsoft spokesperson other than Richardson said that the problem began earlier this week but would not give a timetable for when it might be fixed.

The Sober worm first appeared in 2003 and can hijack a Windows-based computer and force it to repeatedly send spam e-mails. The continuous e-mailing can lead to overloaded servers and reduced network performance. Last month, a variant of the Sober worm was spread as an attachment that claimed to be an old class photo sent by a schoolmate.