leech onto vs attach

leech onto and attach both are verbs.

Word	Noun	Adjective	Verb	Adverb
leech onto	No	No	Yes	No
attach	No	No	Yes	No

As verbs, attach is a hypernym of leech onto; that is, attach is a word with a broader meaning than leech onto:

leech onto (verb)	attach (verb)
admire boundlessly and follow around	become attached
	cause to be attached
	be attached; be in contact with
	take temporary possession of as a security, by legal authority
	create social or emotional ties