Cybercriminals have stepped up efforts exploit the coronavirus crisis by locking hospitals out of their computers unless they pay large ransom payments, Interpol has warned. The international policing organisation said that it had identified a significant increase in attempted ransomware attacks against key organisations involved in the virus response. Ransomware is a form of malicious software that stops organisations from accessing vital files until they pay a ransom – usually in bitcoin – in return for a key to unblock their systems. Interpol has issued a warning notice to its 194 member nations warning of an increased threat from a virus that is believed to earn criminals more than $1 billion a year. One security company has said that it was tracking some 100 ransomware gangs, the majority from Russia and Ukraine. “As hospitals and medical organisations around the world are working non-stop to preserve the well-being of individuals stricken with the coronavirus, they have become targets for ruthless cybercriminals who are looking to make a profit at the expense of sick patients,” said the organisation’s secretary general Jürgen Stock. “Locking hospitals out of their critical systems will not only delay the swift medical response required during these unprecedented times, it could directly lead to deaths.” The ransomware appears to be spread via emails often falsely claiming to contain information from government agencies and encouraging the recipient to click on an infected link. Once a person connects to the link, the virus takes advantage of a flaw in software to replicate throughout a network and infect other vulnerable machines. The virus then encrypts files before informing the user what they have to pay to unlock them. Attacks on hospitals using ransomware are not unknown. A US hospital in California paid the equivalent of $17,000 in bitcoin in 2016 after being targeted by ransomware, the most widespread and financially damaging form of cyberattack. The European policing agency, Europol, said last year that the volume of ransomware attacks appears to have reduced, but attacks were more targeted against institutions with the ability to pay large ransoms. Some of the most serious cases have seen the US city of Atlanta was paralysed for several weeks, and criminal cases in the UK delayed after a large forensics provider to police was targeted. Interpol has previously warned of criminals taking advantage of the pandemic to make money. More than 120 people were arrested in an operation involving 90 countries last month connected to counterfeit facemasks, substandard sanitisers and unauthorised anti-viral medicines. Officials have also identified the sale of fake testing kits and fraudsters seeking to take advantage of the sharp rise in online trading to cheat the unwary and elderly.