i have a question: in the web wallets(hosted wallets)when user want to make a transaction and send the information to the wallet server , can a one change the information(man in the middle attack)?
This is maybe not the correct place for such security questions but I'll try to answer.
It depends on the connection between you and the web wallet server. If the connection is secured (https) then there shouldn't be a possibility for a MITM attack unless the certificate is compromised as the data is encrypted end-to-end. If the connection is not secured (http) then MITM is possible - but in any case you should never use a non-secured wallet.