Is it possible that all current blockchain-based cryptocurrencies (like Bitcoin) can be hacked in just a matter of seconds? It indeed seems possible, based on the statements made by Dr. Joseph Liu, Associate Professor at Monash University.
Dr. Lius qualifications add allot of weight to his statements. He is the Head Researcher at Monash Blockchain Research Lab, the Chief Scientist of HCash and he is also the co-creator of the Moreno cryptocurrency. In other words, his statements about cryptocurrency development should be taken seriously...
https://www.bitcrypt.co/every-cryptocurrency-hacked-in-seconds/When someone hacker has access to the wallet, it is very possible to be able to do hacking against the wallet. So basically that as long as we can keep the wallets we have safely we will get a sense of security too. Take care of all information relating to the wallet and when we use web-based wallets such as exchange, then choose an exchange that does have the best reputation.