The Storm worm is now more streamline and stable after malware authors ditched some key functions from the malicious code, according to researchers from Symantec.

The worm no longer infects other legitimate drivers on the system, instead relying on its own proprietary components to "do its dirty work". It also no longer injects itself into processes such as Explorer.exe, according to a blog post by Symantec security researcher Thomas Parsons.

"The sustained development of the Storm worm (incorporating review cycles) indicates that we will continue to see solid infection rates going forward," wrote Parsons. "So, unlike the natural phenomenon, this storm continues to huff and puff and it doesn't look like it is petering out anytime soon."

The Storm botnet was initially created at the beginning of 2007, when the Storm worm was sent out via spam, hiding in e-mail attachments with a subject line of "230 dead as storm batters Europe".