Approximately 20 percent of machines have yet to patch for the Microsoft Windows Server service vulnerability (MS08-067) that is being exploited to spread the insidious Conficker worm, according to findings from vulnerability management firm Qualys. But the company said that, based on more than 300,000 scans of customers' Windows machines, the number of unpatched machines fell from around 35 percent just before April 1, when Conficker was activated to receive additional updates from preselected domains. — DK