Washington: The malicious "ransomware" attacks that seized computers worldwide Friday and held those systems hostage are likely to worsen this week as millions of people return to work - forcing them to discover the hard way whether they have been affected, security analysts said.
With much of the world still reeling from the digital breach that prevented people from receiving hospital care, a second wave of what European officials have called "the biggest ransomware attack ever" could be devastating, according to Washington Times.
"They're going to turn on their computers in the morning and find out if they were protected or not," said James Barnett, a security expert at Venable and retired Navy rear admiral.
Among those waking up Monday to a nasty surprise could be government officials, some analysts said. Many public computers still have Windows XP installed, and they could be susceptible to the malware if IT administrators have not downloaded the appropriate security patches.
Some federal agencies have moved more quickly than others to stamp out Windows XP, said R. David Edelman, an Obama administration official who advised the White House on technology matters. How adept each agency has been at upgrading its systems has largely to do with available resources.
Cyber security experts rushed to restore systems on Saturday after an unprecedented global wave of cyber attacks that struck targets ranging from Russia's banks to British hospitals and a French carmaker's factories.
The hunt was on for the culprits behind the assault, which was being described as the biggest cyber ransom attack ever.
State agencies and major companies around the world were left reeling by the attacks which blocked access to files and demanded ransom money, forcing them to shut down their computer systems.
"The recent attack is at an unprecedented level and will require a complex international investigation to identify the culprits," said Europol, Europe's policing agency.
The attacks, which experts said affected dozens of countries, used a technique known as ransomware that locks users' files unless they pay the attackers a designated sum in the virtual Bitcoin currency.
Mikko Hypponen, chief research officer at the Helsinki-based cyber security company F-Secure, told AFP that the attack was "the biggest ransomware outbreak in history", saying that 130,000 systems in more than 100 countries had been affected.
He said that Russia and India were hit particularly hard, in large part because the older Windows XP operating software is still widely used in the countries.
The attacks apparently exploited a flaw exposed in documents leaked from the US National Security Agency (NSA).
The attacks hit a whole range of organisations and businesses worldwide.