Google doubled its top bounty - to $100,000 - "for the persistent compromise of a Chromebook in guest mode," the company said, in an effort to attract more researchers.
“Since we introduced the $50,000 reward, we haven't had a successful submission,” researchers wrote in a Monday blog post.
The compromise, delivered via an online form (a link can be found on Google's rewards page), must remain in the device even after it has been rebooted.
Guest mode allows the user to share their device without divulging personal information and is reportedly the mode the when Chromebook uses its highest defensive measures.
The reward will be available year round with no quotas and no maximum reward pool restrictions.
The tech giant is also added a downloading protection bypass bounty for methods that bypass Chrome's Safe Browsing download protection features, which flag potentially malicious urls, the post said.