TechCrunch is reporting that North Korean hackers are targeting bitcoin, and crypto coin exchanges in particular, with its hacking teams.

The tech news website cites a new report from cybersecurity firm FireEye, which claims to have tracked at least five attacks on bitcoin exchanges, or individual bitcoin wallets, within the past six months. The targets reportedly include South Korea-based exchange Yapizon, and two others that were not named.

Korea’s top crypto exchange Bithumb, the world’s fourth largest exchange, is said to have been hacked in late June, while the country’s top Ethereum exchange reportedly lost over US$1 million via a breach earlier this month. But TechCrunch says it isn’t clear whether North Korea was involved in either heist.