In 2010 botnets used to steal banking credentials and other purposes of cyber crooks affected more than 7 times as many victims as the previous year, according to a report by a security firm.

Damballa who released the report says that the increase was driven by improvements in DIY botnet construction kits using which criminals could construct new networks. Upgraded infection technology targets a hard drive's master boot record and changes the machine's boot options also played role.

“Throughout the year, the Top 10 largest botnets increased their total share of all bot infected victims,” the report (PDF) states. “At the beginning of the year approximately 22% of observed botnet victims were infected with malware attributed to just ten botnet operators. By the end of the year, this proportion had grown to nearly 57% - more than doubling their share of global botnet victims.”

Meanwhile, in the period prior to Christmas the overall number of unique botnet victims was 654 percent more than last year.

Apart from updated Zeus crimeware kit, other DIY kits available in underground forums are marketed under names such as Phoenix, Darkness, BlackEnergy, and Eleonore. The packages allow criminals to quickly build botnets without having to write the code from scratch.