Hacks have become a common occurrence in the cryptoworld. This year alone, leading cryptocurrency exchanges including ShapeShift, Gatecoin and Bitfinex have been the victims of massive security breaches. The list is incomplete without the DAO hack that resulted in a reported $60 million ether theft.

A new study conducted by Tyler Moore, assistant professor of cyber security at the University of Tulsa's Tandy School of Computer Science, on the vulnerability of bitcoin exchanges reveals that since bitcoin's inception in 2009 to March 2015, 33 percent of all bitcoin exchanges operational during that period were hacked, Reuters reported.

The figure is quite alarming and highlights the security risk faced by cryptocurrency investors. Moore said the risk of losing funds stored in exchanges is real.

"I am skeptical there's going to be any technological silver bullet that's going to solve security breach problems. No technology, crypto-currency, or financial mechanism can be made safe from hacks," Moore told Reuters.

In addition, Moore’s research also found that the rate of closure for bitcoin exchanges was around 48 percent among those operating from 2009 to March 2015. Notably, these closures were not driven by hacks in each case.

"A 48 percent closure is not acceptable, but not surprising given that bitcoin is a new technology," Richard Johnson, vice president of market structure and technology at Greenwich Associates, told Reuters.

In case of a hack of customers' checking accounts, there is always a third party at the bank to deal with the theft. Darin Stanchfield, chief executive officer at KeepKey, told Reuters that the digital currency ecosystem lacks this feature, adding that he expects more of these attacks to happen.

"Unfortunately because of its irreversible nature, bitcoin requires near perfect security”, Stanchfield said.

The study, funded by the U.S. Department of Homeland Security, will be published soon. Moore has collaborated on the research with Nicolas Christin, associate research professor at Carnegie Mellon University and Janos Szurdi, a Ph.D. student also at Carnegie.

In 2013, Moore and Christin collaborated on a research paper entitled “Beware of the Middleman: Empirical Analysis of Bitcoin Exchange Risk” in which they examined the track record of 40 Bitcoin exchanges established over three years preceding 2013, and found that 18 exchanges closed, with customer account balances often wiped out.