Hackers doubled their cryptocurrency loot in the first half of the year, according to data from blockchain research firm TRM Labs.

Based on the research, $1.38 billion worth of cryptocurrencies. were stolen between January 1 and June 24, more than double the $657 million stolen during the same period in 2023. Like last year, a small number of large-scale attacks led to an increase in stolen cryptocurrencies, with 70% of the total loot coming from just 5 attacks.

The most common forms of attack include breaching “private keys” (the most important factor in cryptocurrency security) but also passphrases (a sequence of random words that stores the information needed to access or retrieve a crypto wallet) said the TRM Labs.

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The hackers used stolen “private keys”, or the method of “address poisoning” (the hacker sends a small amount of cryptocurrency from a digital wallet with a fake address, which has “mimicked” the first and last six characters of the real wallet address with aimed at tricking the victim into sending money to the fake wallet).

Cryptocurrency addresses consist of long, complex strings of characters that are difficult to remember.

According to TRM Labs there have been no substantial changes in the cryptocurrency security ecosystem that have led to an increase in attacks. As he explained, the number of attacks does not vary significantly from year to year. However, he pointed out that what has changed is the prices of cryptocurrencies which were, on average, higher in the first half of the year, which may have contributed to the increase in the value of the stolen coins.