Dutch cybersecurity companies have issued warnings to thousands of companies about a global ransomware attack. The attackers, known as the Cactus Gang, are from Eastern Europe and have been active since the end of last year. The gang penetrated the companies' networks because the companies used a Qlik Sense server. The Dutch experts said they discovered that many of these servers are vulnerable to ransomware attacks. The experts work for Delft security company Fox-IT, Northwave from Utrecht, Responders from Amsterdam, and ESET from Sliedrecht.