The fourth Pwnium hacking competition will be held in March, and this year Google is offering some major prizes for anyone who can subvert its Chrome OS.

And, for the first time, it's not as picky about its hardware.

"Past Pwnium competitions have focused on Intel-based Chrome OS devices, but this year researchers can choose between an ARM-based Chromebook, the HP Chromebook 11 (WiFi), or the Acer C720 Chromebook (2GB WiFi) that is based on the Intel Haswell microarchitecture," said Google security engineer Jorge Lucángeli Obes.

Crackers will get $150,000 for a successful webpage-based attack on a Chromebook that installs persistent malware against a guest or logged-in user. To bag $110,000, an attacker must compromise the browser or the entire system from a guest user account on Chrome OS, with "significant bonuses" for other interesting attacks, up to a limit of $2.71828m.

That figure's not random by the way, just Google geekery in action again. It's the value of the natural logarithm to the base e, although there's been some rounding in Mountain View's interpretation of the figure.

The attack has to be made against the latest build of Chrome OS running default software only and, based on Google's prior form, the Chocolate Factory's engineers will be updating the operating system right up to the last moment.

The contest will take place at the annual CanSecWest security conference in Vancouver on March 15, and Google will be writing checks on the day and afterwards. Successful hackers will also get to keep the hardware they pwn. ®