For years, North Korea’s stealthy hackers and scam IT workers have infiltrated companies, stealing corporate secrets and plundering billions in cryptocurrency to help fund the totalitarian regime and its weapons programs. Since Greece-based cybersecurity researcher Vangelis Stykas gained access to North Korean systems 22 months ago, he says, he has found evidence that 1,640 companies across 57 countries have been impacted by the country’s hacking operations. Among these, Stykas will detail at the Black Hat security conference in Las Vegas today, around 700 to 800 of the impacted organizations have had “really damaging” intrusions. In some cases, he notes, the hackers appeared to have infected themselves with their own malware—which, as a result, gave him access to the hackers’ workstations, too. Japan’s Computer Emergency Response Team says it confirmed the security researcher’s findings and worked with AEON Smart Technology on “remediation.”