When connecting to a unknown public hotspot, I know that the data transmitted can be captured and, if unencrypted, easily analyzed. But that's not the question here.
I want to know whether the information saved on the computers (company computers running Windows 7 - 8 or some Linux installations, some smartphones, Androids and iPhones), which is not being transmitted, is also at risk? Can a computer be cracked just because it's connected to the hotspot?
If the answer is yes, what would be an appropriate security policy to deal with it? Prohibiting connecting would be a more extreme measure, is there anything else?