The change comes after new US regulations restricting technology and other exports, meant to curb Beijing's acquisition of technology under civilian pretenses.
The Guardicore researchers informed Comcast of the breach and worked with them to fix the problem.
With roughly a billion monthly users, the possible damage a security breach in the popular social media application might cause is enormous.
A spokesman for the Trump campaign did not respond to a request for comment. The Biden campaign declined to comment on its work with Cloudflare or any attacks on its websites.
The US, Israel and many other countries are planning on relying heavily on Zoom for all or part of children’s schooling starting in early September.
In a statement, Twitter said it appreciated the "swift actions of law enforcement."
The hackers were after specific employees who had access to account support tools used by Twitter's support teams.
An activist claimed Hong Kong police used Israeli-made Cellebrite to hack his phone.
Beijing has repeatedly denied hacking the United States and other rival powers.