Web Wallet online rentan sekali diretas baik itu oleh hacker atau pemilik web itu sendiri jadi gak ada jaminan keamanan yang mutlak di sini.
Baca mengenai blockchain.com di sini :
https://bitcointalksearch.org/topic/blockchaincom-scam-lost-funds-5157460
https://bitcointalksearch.org/topic/urgent-a-2nd-hack-into-our-blockchain-wallet-5078190
https://bitcointalksearch.org/topic/is-this-a-blockchaininfo-scam-2410394
https://bitcointalksearch.org/topic/blockchain-com-5158020
https://www.coindesk.com/good-samaritan-blockchain-hacker-returned-255-btc-speaks