The company said in its quarterly threat report on Tuesday that over the first quarter of 2009, the number of IP addresses connected to botnet use soared to more than twelve million. That figure eclipses the previous high, set in the third quarter of 2008.
The US and China accounted for more than a fifth of the new infections with 18 and 13 per cent respectively. Australia was third on the list with 6.3 per cent, followed by Germany with 5.3 per cent and the UK with 4.7 per cent.
The increase in botnet recruitment comes despite spam levels that are down from the same period last year. McAfee researchers suggested that a major increase may be on the horizon, however.
"The third quarter of 2008 also posted a record number of new zombies, but it was exceeded this quarter by one million," the company said.
"And although the spam volume levels have not yet recovered from the McColo shutdown, the activity level of new zombies indicates that the spammers are working hard to regain the infrastructure lost and that volumes will return to previous levels soon."
Aside from leading in infection levels, the US was also top in sending spam. Machines from within the US were responsible for more than one third of the global spam load.
"US automakers may be struggling with manufacturing and sales problems, but spam production from the United States continues to lead the world, accounting for 35 percent of global spam output," the company noted.
"Although spam command-and-control operations are an international infrastructure, spammers still favor using computers from the United States to manufacture spam."