Anyway, Klez was destructive because of the manner in which it executes the infection. Klez is another virus that spreads through email (seeing a pattern here?). Unlike Mydoom, it didn’t have specific targets, and its indiscriminate nature made it all the more destructive.Īt the peak of its transmission, which was during the spread of the Sobig.F variant, it clogged and took down the email system at MIT - yes, the Massachusetts Institute of Technology, whose largest and most popular undergraduate program is the Electrical Engineering and Computer Science program.Īnd that’s the thing about Sobig: It’s not complicated and it doesn’t damage files and computers directly, but the sheer rate at which it spreads and its ability to infect a computer multiple times is enough to clog networks and disrupt processes. Just like Mydoom, Sobig spread through spam emails.

SobigĪt $30 billion, the damage caused by Sobig was - please excuse the pun - so big. The effect of the attack on Microsoft was minimal, but for The SCO Group, the threat forced it to preemptively shut down its site, costing the company a large amount of its fortune. The second variant targeted Microsoft’s website two days later. For some reason, the first variant of Mydoom contained a payload scheduled to execute a distributed denial of service (DDoS) attack on The SCO Group’s website on February 1, 2004. The biggest losses came from two companies in particular: The SCO Group and Microsoft. The sheer amount of spam emails was enough to overload computers and even force businesses to close for days to repair their systems. It’s even said that 16 to 25 percent of all emails sent in 2004 were generated by this virus.

In January 2004, Mydoom spread like wildfire through emails. “Mydoom” has such an ominous ring to it, and the virus lived up to its name. That’s how the following viruses cost their targets billions. They targeted businesses, disrupted business operations, stole corporate secrets, and leaked company data. But the costliest computer viruses didn’t just target individuals. Unless you’re a crypto trader or you have a working design for a time machine, the contents of your computer probably won’t amount to millions, let alone billions, of dollars.

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