At least 2 million people received the email May 16 notifying them that an order they had just made on "Wallmart's" website was being processed, though none of them had done any such thing.
Sharing on social media helps hackers sharpen "spear phishing" attacks they use to trick their way into computers, security experts said Monday.
Revelations about the US government's vast data collection programs have already started hurting American technology firms, according to an industry survey released this week.
China and Indonesia headed the list of 177 countries named as sources of Internet attacks, a security survey said Tuesday.
Cybercrime costs the global economy between $100 billion and $500 billion annually, according to a study released Monday which acknowledged more data is needed for precise estimates.
The massive cyber attacks on South Korean banks and broadcasters earlier this year were part of a broad campaign of cyber espionage which dates back at least to 2009, a US security firm has concluded.
The special committee set up by Dell to evaluate options for the troubled computer giant warned Friday of "substantial downside risk" if shareholders reject a buyout plan led by founder Michael Dell.
IT hub Estonia on Wednesday urged the European Union to rely less on US firms for "cloud" data storage, amid tensions over claims of US spying and data surveillance.