90% e-mails are spam: Report

Armies of hijacked computers are flooding the world with spam as hackers devise slicker ways to take over unwitting people's machines, according to a report released on Monday.

Virus-infected computers are woven into "botnets" used to attack more machines and to send sales pitches to e-mail addresses in low-cost quests to bilk readers out of cash.

"Every year we see threats evolve as criminals discover new ways to exploit people, networks and the Internet," said Cisco chief security researcher Patrick Peterson, who was involved in drafting the report.