Three of the most virulent malware threats attacking PCs this month can run on Microsoft's Vista OS, launched today.
Internet security software firm Sophos said Stratio-Zip, Netsky-D and MyDoom-O were able to bypass Vista's defences when accessed via a third-party web e-mail client.
This represents a serious issue for businesses who allow employees to access their personal e-mail at work, as well as for companies that are considering adopting an alternative e-mail client.
"There has been much speculation about whether Vista would render existing malware extinct, and the news is now in - it won't," said Carole Theriault, senior security consultant at Sophos.
"While Microsoft should be commended for the huge security improvements it has made in Vista, running separate security software is still essential to eliminate the risk of infection. On top of this, cyber criminals will already be looking at creating Vista-specific malware," she said.
Sophos tested each piece of malware in the top ten on the Vista operating system to establish whether users running Vista without any third-party security software would avoid infection.
The results showed that while the Windows Mail e-mail client (Vista's upgrade of Outlook) was able to identify and halt all of the threats, third party webmail software let three of them in.
Sophos said that the Stratio-Zip worm overtook the Netsky-P threat as the most widely circulated piece of malware in November, accounting for one third of the total number of reports.
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