First, the thief took all the BTC in my wallet. This was the transaction:
https://blockchain.info/tx/d6c75c6914c598d19fd6c0f73da0b009786e6585c57c6023ffbebdd6d7d0fecfI used the Bitcoin-QT wallet, but I used it without any password protection. Could that be the entering gate of the thief? The thing is that the machine is a newly installed windows and I did not download anything special to it.
As a consequence, I opened an online wallet on blockchain.info with mobile 2FA and including all the security options they provide. I imported the old private key from Bitcoin-QT, where my miner sent some minor BTC:
https://blockchain.info/tx/fee2c98ead5078127b3cbb8812332f1fa110f7326d65f0f577fa0e6ee38fe861Can this cause any risk to the new private key of the new BTC address? I will wait another week and the I delete this address from this wallet since my miner has still some immature BTC.
Thx for your advise and best regards
No, running bitcoin core does not make you vulnerable. No matter if your wallet is encrypted or not.
Importing a compromised private key is a bad idea. Someone else also has that key, using it is not advised. Change the payout address on your pool.
The compromised private key can not compromise any other keys in your new wallet.
Finally: what do you consider "nothing special"? Some Altcoin wallets have trojans in them...