[TUHS] Cool talk on Unix and Sendmail history, by Eric Allman

[Douglas McIlroy]

"Lessons learned" overlooked the Morris worm, which exploited not only
the unpardonable gets interface, but also the unpardonable back door
that Allman built into sendmail.

This reminds me of how I agonized over Mike Lesk's refusal to remove
remote execution from uucp. (Like Eric, Mike created the feature to
help fix the myriad trouble reports these communication facilities
stimulated.) It seemed irresponsible to distribute v7 with the feature
present, yet the rest of uucp provided an almost indispensable
service. The fig leaf for allowing uucp in the distribution was that
remote execution was described in the manual. If you didn't like it
you could delete or fix uucp. (Sendmail's Trojan horse was
undocumented, though visible in the code.)

Doug