Only the IT security team should attempt a reboot.Ĭentral to your response is whether to pay the ransom. If possible, they should physically take the computer they’ve been using to their IT department.

Stuxnet: This worm is reported to have destroyed Iranian nuclear centrifuges by sending damaging instructions.Once your users detect a ransomware demand or virus, they should immediately disconnect from the network.Conficker: This 2009 virus still infects many legacy systems and could do significant damage if it ever activates.In 2020, there’s now more malware on Macs than on PCs. Flashback: A Mac-only virus, Flashback infected over 600,000 Macs in 2012 and even infected Apple’s home base in Cupertino, Calif.

FBI estimated cleanup and repair costs at $80 million.

Melissa: The most dangerous computer virus in 1999, Melissa sent copies of itself that looked like NSFW pics.

Explorezip: This worm used fake emails to spread to every machine on thousands of local networks.

Sircam: A computer worm from 2001 that used counterfeit emails with the subject line, “I send you this file in order to have your advice.”.

Tanatos/Bugbear: A 2002 keylogger virus that targeted financial institutions and spread to 150 countries.

Storm Worm: This worm showed up in 2007 and attacked millions of computers with an email about approaching bad weather.

Its financial cost has been pegged at $10.4 billion, but not reliably.

Swen: Written in C++, the Swen computer worm disguised itself to look like a 2003 OS update.

Yaha: Yet another worm with several variants, thought to be the result of a cyber-war between Pakistan and India.

Mimail: This worm tried to harvest data from infected machines to launch a string of DDoS attacks, but was relatively easy to remove.Here are just a few more viruses that have wreaked havoc over the years: With a million new malware programs popping up every 3 years, we may miss the forest for a few outstanding trees. The top 10 worst computer viruses above are just the ugly tip of a gargantuan digital iceberg.

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