how can a keylogger in windows read unbutu OS when i am running windows? becuz i can only run 1 os at a time with dual boot.. whats the risk like? 1%? or 0.00000001%? (if i scan my usb stick with a virus scanner if i wanna sign files)
If you were very unlucky, and your online OS was compromised, someone could write code to read uninitialized RAM. When you use "reboot" the 1s and 0s on the RAM can stick around, and it could be possible someone could read that from your Ubuntu session and look for your seed. (though this would be VERY unlikely, and could be easily solved by turning off your computer, unplugging it and waiting 10 seconds, then plugging it back in an turning it on.)
However, the far more likely problem you will most likely run into is:
1. you "reboot" into Ubuntu.
2. You leave the LAN cable plugged in, because you think Ubuntu is set to disable Network adapter.
3. For some reason, when you boot, Ubuntu has activated the network adapter and is trying to connect to the net.
Which is why I recommend unplugging the physical LAN cable itself whenever you boot your cold storage, and when you switch back to online boot, unplug the electricity for 10 seconds. (this wipes the 1s from the RAM)
