Obviously, fraudsters can influence the price of ETH because they always sell the crypto collected during the ICO phase in exchange for legal tender, which will cause the price of Ethereum to fall.
Not just ETH but I think the whole market. Hackers are one of the problem of cryptomarket and its hard to stop them from doing that, because of this the trust of investors on cryptocurrency is declining and that can lead to a price drop of ETH, BTC and other altcoins. ICOs are still suffering from this trust issue, but hopefully they can survive in 2019, so they can have more technologies to offer great services to us.