The month of August has been a challenge for computer networks, with two large viruses causing widespread damage, despite a drop in hacker attacks. In recent months, hack attacks had been a significant problem, largely politically motivated by the situation in the Middle East and the war in Iraq specifically. But this month has been characterized by “malware” or worm and virus attacks. MSblast, also called LoveSan, hit in mid-August, causing an estimated US$525 million in economic damage, according to international digital risk firm mi2g. But overshadowing this has been the latest strain of the Sobig virus, which hit later in the month. Overall, Sobig has caused an estimated US$7.09 billion in economic damage, ranking it the third most damaging virus ever. It follows Klez malware at US$13.94 billion, and Love Bug at US$8.75 billion.Economic damage is calculated based on productivity loss data samples and estimates of the number of machines affected and bandwidth lost. In just two days, between Wednesday and Thursday this week, the malware’s damage estimate rose from US$5.59 billion to US$7.05 billion. Mi2g notes that people have been returning from holidays and opening email, contributing to the perpetuation of Sobig. As well, “clean” machines are even beeing choked by the virus, receiving continuous “returned mail messages”.