CryptoLocker was particularly successful , procuring an estimated US $3 million before it was taken down by authorities .
CryptoWall was estimated by the US Federal Bureau of Investigation ( FBI ) to have accrued over US $18 m by June 2015 .
CryptoLocker was particularly successful , procuring an estimated US $3 million before it was taken down by authorities , and CryptoWall was estimated by the US Federal Bureau of Investigation ( FBI ) to have accrued over US $18 m by June 2015 .