REQUEST
Could the OP, or someone knowledgeable on this type of situation, speculate on the ACTUAL mechanism of this attack? What did the OP actually do, that gave away his private key? Was it stolen from the computer's clip board (copy/paste?)
Knowing HOW this kind of stuff happens will make it easier for other people to be more secure.
Thanks
I'm still investigating, I'll update when I find the exact mechanism.
I've also just realised that the attacker took 120 Litecoin from me on the 22nd of September, so my computer had been compromised for at least 18 days.
https://live.blockcypher.com/ltc/tx/852187add4e47fb1c25df7df7d6efd9c19f4ebf3bda0e4d1e5d7793bf1fc5e33/