Are there any protection againts heisting the "shell builtin"s?

[jim hook]

test$ cd
rmplayer
test$
test$ type cd
cd is a function
test$
test$ tail -4 .profile
cd()
{
echo rmplayer
}
test$
test$ uname -mrs
OpenBSD 6.9 amd64
test$

Thinking of that home dirs could be on a shared storage, that can be accessed 
by others and maliciously modify the ".profile", etc. files of the targeted 
user.

ex.: "unset cd" would help, but any solution in general?

Thanks.