BOSTON -- The single biggest global ransomware attack yet continued to bite Monday as details emerged on how the Russia-linked gang responsible breached the company whose software was the conduit. In essence, the criminals used a tool that helps protect against malware to spread it widely.
An affiliate of the notorious REvil gang, best known for extorting $11 million from the meat-processor JBS in a Memorial Day attack, infected thousands of victims in at least 17 countries Friday, largely through firms that remotely manage IT infrastructure for multiple customers, cybersecurity researchers said.
REvil was demanding ransoms of up to $5 million. But late Sunday it offered in a posting on its dark web site a universal decryptor software key that would unscramble all affected machines in exchange for $70 million in cryptocurrency. It wasn't clear who they expected might pay that amount.
Sweden may have been hardest hit by the attack -- or at least most transparent about it. Its defense minister, Peter Hultqvist, on Monday bemoaned "a serious attack on basic functions in Swedish society."
"It shows how fragile the system is when it comes to IT security and that you must constantly work to develop your ability to defend yourself," he said in a TV interview.
Most of the Swedish grocery chain Coop's 800 stores were closed all weekend because their cash register software supplier was crippled. They remained closed Monday. A Swedish pharmacy chain, a gas station chain, the state railway and public broadcaster SVT were also hit.
A broad array of businesses and public agencies were affected, including in financial services, travel and leisure and the public sector -- though few large companies, the cybersecurity firm Sophos reported. The cybersecurity firm ESET identified victims in countries including the United Kingdom, South Africa, Canada, Argentina, Mexico, Indonesia, New Zealand and Kenya.
Ransomware criminals infiltrate networks and sow malware that cripples them by scrambling all their data. Victims get a decoder key when they pay up.
In Germany, an unnamed IT services company told authorities several thousand of its customers were compromised, the news agency dpa reported. Also among reported victims were two big Dutch IT services companies -- VelzArt and Hoppenbrouwer Techniek. Most ransomware victims don't publicly report attacks or disclose if they've paid ransoms.
On Sunday, the FBI said in a statement that while it was investigating the attack, its scale "may make it so that we are unable to respond to each victim individually." Deputy National Security Advisor Anne Neuberger later issued a statement saying President Joe Biden had "directed the full resources of the government to investigate this incident" and urged all who believed they were compromised to alert the FBI.
Biden suggested Saturday the U.S. would respond if it was determined that the Kremlin is at all involved. Less than a month ago, Biden pressed Russian President Vladimir Putin to stop giving safe haven to REvil and other ransomware gangs whose unrelenting extortionary attacks the U.S. deems a national security threat.
On Monday, Putin spokesman Dmitry Peskov was asked if Russia was aware of the attack or had looked into it. He said no, but suggested it could be discussed by the U.S. and Russia in consultations on cybersecurity issues for which no timeline has been specified.
Experts say it was no coincidence that REvil launched the attack at the start of the Fourth of July holiday weekend, knowing U.S. offices would be lightly staffed and many victims might not learn of it until back at work Monday or Tuesday.
Information for this article was contributed by Jim Heintz, Jan Olsen, Kirsten Grieshaber, Jari Tanner and Sylvie Corbet of The Associated Press.