FUD doesn’t always measure up to reality, says Sarah Jacobsson Purewal. Conficker worm was believed to be one of the largest computer infections since 2003. ILOVEYOU virus was particularly effective for two reasons: It was sent from “safe” senders (those already in the recipient’s address book) and the file resembled a text file. The Pentagon, the CIA, and the British Parliament all had to shut down their e-mail systems after the virus started spreading.”]
Source: https://www.csoonline.com/article/2134565/the-infosec-terror-train.html