"Time to organize collective readings of Snowden book everywhere," the hackers' email reads, claiming to have a copy of the bestselling book in a booby-trapped Microsoft Word document.
Last month, Twitter took down almost 200,000 China-linked accounts that were trying to undermine the protests in Hong Kong.
The ruling is meant to help cut down on spam and robotexts.
Twitter: "We're testing new measures to challenge accounts that use terms commonly associated with spam."
The culprits—who threaten to release footage to the victims' contacts—have made around $125,000 from the scheme.
A malicious spam campaign seeks to capitalize on fears surrounding the Zika virus.