A cyberattack is wreaking computer havoc around the globe. Analysts say it's struck 150 countries, affecting everything from corporations to hospitals.
Tom Bossert, a Homeland Security advisor to President Donald Trump, told ABC's "Good Morning America" that the virus is an "extremely serious threat" that could lead to copycat attacks.
He added "for right now, we've got it under control" in the U.S.
The attack began Friday and has hit more than 200,000 victims, including companies like FedEx in the U.S., Britain's hospital network, Germany's national railway and Chinese universities.
Security expert and Redlock CEO Varun Badhwar said the attack is unprecedented.
"We've never seen something spread this quickly in a 24-hour period across these many countries and continents," he said.
How It Works
The malware virus is known as "WannaCry." Ben Rapp, CEO of the tech security firm Managed Networks, says it starts with a simple email.
"A user will receive an email and that email will have a document attached to it and the email will be what we call socially engineered, so it will name the person," he explained. "It will give an impression that there is a really good reason why they should open that document -- it's an invoice they haven't paid. It's a lottery they've won, something like that."
The virus has afflicted almost 30,000 institutions in China. In the United Kingdom, hospitals have been forced to delay surgeries and turn away patients in the National Health Service (NHS).
Experts say there's no political agenda behind the attacks -- just old-fashioned blackmail. The virus assailants issue a ransom note to those crippled by their attack, asking for $300. If there's no response, the attackers raise the amount to $600 and ultimately threaten to destroy files.
The virus attacks a loophole in the widely-used Microsoft Windows operating system that runs computers. Microsoft, however, is pointing the finger at U.S. intelligence agencies for "stockpiling" software code that hackers can obtain.
Installing a Microsoft patch is one way to protect computers against the virus. It's also possible to disable a type of software that connects computers to printers and faxes which the virus can exploit.
The president has reportedly called an emergency meeting to assess the threat the virus poses to the U.S. Just last week, he issued an executive order on cyber security which won early support on Capitol Hill.