The campaign, dubbed COATHANGER, has been linked to communist China and it exploited a zero-day vulnerability in the FortiGate firewall system used by the Netherlands and other nations on many government networks. Zero-day vulnerabilities exist when a software update is first deployed.
Dutch intelligence’s original report, released in February, said that damage from the breach was limited because of "network segmentation," which separates an affected system from the nation’s wider defense network.
The Netherlands’ National Cyber Security Center (NCSC) announced on June 10, however, that the Chinese cyber campaign is far larger than previously thought.
NCSC said that COATHANGER compromised 20,000 systems across dozens of Western governments, international organizations, and a large number of companies within the defense industry.