Report: Yahoo customized surveillance software for NSA

Yahoo built custom software for U.S. intelligence agencies last year so the agencies could scan customers' incoming email for specific information.

According to an Oct. 4 report from Reuters, two former employees of the company and a third person familiar with the activity said Yahoo built the program in response to a request from either the FBI or the National Security Agency to comply with a classified U.S. government directive sent to the company's legal team.

The report states that the software scanned "hundreds of millions of emails" in what it called the first known case of a U.S. internet provider agreeing to conduct surveillance on all arriving email instead of looking at bulk stored messages or a handful of messages in real time.

The former Yahoo employees told Reuters that CEO Marissa Mayer's decision to obey the government directive split its top management and led to Chief Information Security Officer Alex Stamos' departure from the company in June 2015.

The object of the surveillance is not clear. The Reuters report states that intelligence agencies were seeking a "set of characters," which could mean a word or phrase but also an encryption key or some other piece of code. The same request was probably sent to other Internet providers, according to the report.

"If true, the government's directive to Yahoo to write a software program and search all of its customers' incoming emails for certain content is a gross abuse of federal power," said Rep. Ted Lieu (D-Calif.) in a statement. "Private-sector companies and private citizens are not an arm of law enforcement or an extension of our intelligence agencies."

A June 14, 2015, report in the New York Times based on documents provided by Edward Snowden offers the clue that cybersecurity might be an issue. That article revealed that a 2012 directive by the Obama administration expanded warrantless monitoring on international internet lines with to the goal of identifying suspicious internet addresses and malware with signatures traceable to foreign governments.

The surveillance described in the Reuters report took place before passage of the Cybersecurity Act of 2015, which was included in the fiscal 2016 appropriations package. That law provides for the sharing of classified cybersecurity threat indicators between government and industry and could facilitate the scanning of commercial network traffic for malware.