Experts are warning that hackers have yet to activate the payload of the Conficker virus.
The worm is spreading through low security networks, memory sticks, and PCs without current security updates.
The malicious program - also known as Downadup or Kido - was first discovered in October 2008.
Although the spread of the worm appears to be levelling off, there are fears someone could easily take control of any and all of the 9.5m infected PCs.
Speaking to the BBC, F-Secure's chief research officer, Mikko Hypponen, said there was still a real risk to users.
"Total infections appear to be peaking. That said, a full count is hard, because we also don't know how many machines are being cleaned. But we estimate there are still more than 9m infected PCs world wide.

full story: BBC NEWS | Technology | Clock ticking on worm attack code