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　　An old Internet scam is getting some new attention lately. It is called "ransomware."

　　Ransomware is a term used for a specific type of software that locks up files or access to a computer until money is paid.

　　Earlier this year, the Federal Bureau of Investigation, or FBI, issued a warning about an increase in the spread of ransomware in the U.S.

　　Two of the most widespread ransomware are CryptoLocker and CryptoWall. The two computer bugs are thought to have taken millions of dollars from people. The Internet security company Websense says it has found about two million cases of Cryptolocker. More than 60 percent of the cases were in Australia.

　　A man using a computer keyboard to enter data in Warsaw, Poland.
　　Symantec is another Internet security company. It says a newer ransomware is quickly spreading around the world. The bug fools people with information on the popular television series "Breaking Bad."

　　The bug secretly searches out certain types of files in computers and encrypts them. Computer users will not be able to open those encrypted files without the decryption key. And only the person or persons responsible for the bug have the key.

　　Users then receive messages that their files are now unavailable. They are told their files will remain unavailable unless the user pays a fee in exchange for the decryption key to unlock their documents.

　　John Shier is a security expert at the cybersecurity company Sophos. He says ransomware looks for "user-generated content – word documents, spreadsheets, pictures. These could be pictures of your child's first birthday, videos of your honeymoon, financial spreadsheets of your small business; files that you really care about."

　　The price to have those files returned is usually between $300 and $600. Once the payment is made, the user is given the decryption key.

　　Ransomware bugs have a relatively simple design. But they often have a complex encryption standard. That makes them almost impossible to break without the decryption key.

　　Ransomware targets all types of computer systems - personal, business and government.

　　But Mr. Shier says "the most success the bad guys are seeing" is from personal computer systems.

　　Little can be done once a device has been infected. But there are ways to protect against ransomware or limit the damage done once infected. John Shier says the best way is to make many copies of all of your files and save them in different locations.

　　I'm Jonathan Evans.

　　Doug Bernard reported this story from Washington. Jonathan Evans adapted it for Learning English. Hai Do was the editor.

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