Sobig.F was the most prevalent virus during the past quarter, according to an Australian report.
The quarterly report, put together by software vendor Computer Associates (CA) found that viral activity had increased by 420 percent over the period.
Sobig.F topped the list, followed by Bugbear.B, with Klez.H ranked as the third most prevalent virus during the quarter.
Daniel Zatz, senior security consultant at CA, told iTnews that its Australian research and development centre had seen a huge spike from Sobig.F. The virus generated over 60 times as many samples as Bugbear.B, according to the vendor.
"In general, every quarter you're going to get one that stands out quite significantly," Zatz said.
The widespread propagation of Sobig.F was due to a flaw in its code, where the address log failed to register addresses, leading to the virus being sent to the same machines multiple times. However, Zatz said that despite the worm generating a huge surge in traffic samples, it was unlikely that the actual infections were much greater than Sobig.E.
He said that the statistics in the report were based on virus samples that were collected from users for analysis by its research and development centre.
Blaster, which CA described as "having the highest impact for the quarter", wasn't listed in the report because it didn't propagate by email. The report also recorded 1,390 new viruses during the quarter.