The number of exploited vulnerabilities jumped dramatically last month, with more than 60 percent of new vulnerabilities being exploited, a new report says.

Exploit activity is typically at a rate of 30 to 40 percent, according to Fortinet's newly released January 2011 Threat Landscape report. Close to half of "critical" vulnerabilities were exploited by attackers, the report found.

"It is no secret that software vulnerabilities continue to be disclosed in large numbers on an ongoing basis -- especially critically rated ones," said Derek Manky, senior security strategist at Fortinet's FortiGuard Labs. "Hackers are sinking their teeth into unprotected systems, thanks to readily available exploit code and attack frameworks that support these new vulnerabilities. Since they are freshly disclosed, not everyone may have up-to-date signatures or proper patches in place."

At the top of the list of malware detected by Fortinet were the Feebs, Buzus, and Virut families. "These are not new threats, yet they remain quite persistent and active. Feebs is a mass mailer that uses Javascript to infect systems: the mail will contain a password protected archive, along with the information in the mail body. Buzus continues to be active in the spam scene, sending infected attachments of itself using a variety of spam campaigns linked to Twitter, Facebook, Google, Hallmark and Hi5. They’re clearly putting more effort into their social engineering tactics by leveraging well known names," Manky blogged.

Virut is especially difficult because it contains a bot component, he said in his post. "FortiGuard Labs observed Virut downloading other botnets (VBCF) -- meaning an infected system would soon have multiple pieces of malware in place. Virut is one of the most persistent botnets we see today, since it is tough to remove from an infected system, uses a public IRC domain (has not been taken offline during its four-year run), and has hybrid spreading capabilities."

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