Going through old files, I found this printout from Nov, 9, 1988 — an account and analysis of the Morris worm [1]. I and others received it by email at Apollo Computer. I'm not bothering to reproduce more than the first page of the email, because this report is available in usable form in many places around the net, e.g. here [2].
Robert Tappan Morris wrote the first internet worm. Within 15 hours of its release to the wild it had infected (and disabled) a few thousand Unix machines, amounting probably to a single-digit percentage of the machines then online.
[1] https://en.wikipedia.org/wiki/Morris_worm
[2] https://www.ecb.torontomu.ca/~elf/hack/iworm.html