however. its complicated as the block will have to pass the difficulty threshold to pass one of the security checks. (blockhash needs to have certain amount of 0000's .. which means alot of hashpower to achieve such. meaning its expensive to achieve
so yes its possible. but not cheap.
And would it be possible for the attacker to fake the hashpower? As he has all the nodes he can modify the bitcoind in order to drop the difficulty and to mine with a CPU, but to communicate to "blockchain" the hashpower multiplied by let say 10
whatever?
And another thought. What if the attacker performs the same attack without inviting his victim to a physical place, just by knowing the victims IP and isolating from him the right net and offering only connections to the fake nodes?
where it is definetly possible and practical to do. is the lite wallets that dont involve validating blocks at client/user level where the lite wallet only gets UTXO data which can easily be faked on a closed internet
So should the attacker be certain his victim only uses a lite wallet he can invite his victim to his home to receive the payment?
And again I'd like to make it clear what is the purpose of this question. People are often ask and speak about wide BTC adoption here. But should this issue exist it can be the cause of many scams in the places like Africa, for instance, where many people have a mobile phone and also a free internet connection, but only... enabled to use Facebook and Whatsapp. So with a high degree of probability the sender's home wi-fi would be used in the above described transaction.
The BTC blockchain is becoming more and more heavy, so more and more people are switching to lite wallets. I don't know whether a 10% of people are using a full wallet anymore. Does it mean that this kind of attack is something to consider?