Rustock attacks peaked over the summer, accounting for 21 percent of all threat events recorded by Cisco over the quarter.

According to Cisco, the Rustock botnet topped security issues encountered by the company's Remote Operations Services over the past three months, reports V3.co.uk. The malware peaked over the summer, accounting for 21 percent of all threat events recorded by Cisco over the quarter.

Cisco also noted that despite the security problems that have plagued Adobe software, overall attacks targeting the Adobe platform dropped in recent months. Just one percent of attacks exploited Reader and Acrobat flaws in September. That's down from 3 percent in July.

Other findings: Java attacks became increasingly popular over the quarter, jumping to 7 percent of all Web malware in September. That's up from 5 percent in July. This falls in line with a Microsoft warning issued in October of an "unprecedented wave" of attacks exploiting vulnerabilities in Oracle's Java software.