Ransomware first became popular in Russia. Now the use of ransomware scams has grown internationally. In June 2013, McAfee said it had collected over 250,000 unique samples of ransomware in the first three months of 2013. This is more than double the number of the previous year. CryptoLocker, a ransomware worm that surfaced in late-2013, had collected an estimated $3 million USD before it was taken down by authorities.