The National Security Agency has implanted software in nearly 100,000 computers around the world that allows the United States to conduct surveillance on those machines and can also create a digital highway for launching cyberattacks.
While most of the software is inserted by gaining access to computer networks, the N.S.A. has increasingly made use of a secret technology that enables it to enter and alter data in computers even if they are not connected to the Internet, according to N.S.A. documents, computer experts and American officials.
The technology, which the agency has used since at least 2008, relies on a covert channel of radio waves that can be transmitted from tiny circuit boards and USB cards inserted surreptitiously into the computers. In some cases, they are sent to a briefcase-size relay station that intelligence agencies can set up miles away from the target.
The N.S.A. calls its efforts more an act of “active defense” against foreign cyberattacks than a tool to go on the offensive. But when Chinese attackers place similar software on the computer systems of American companies or government agencies, American officials have protested, often at the presidential level.
Among the most frequent targets of the N.S.A. and its Pentagon partner, United States Cyber Command, have been units of the Chinese Army, which the United States has accused of launching regular digital probes and attacks on American industrial and military targets, usually to steal secrets or intellectual property. But the program, code-named Quantum, has also been successful in inserting software into Russian military networks and systems used by the Mexican police and drug cartels, trade institutions inside the European Union, and sometime partners against terrorism like Saudi Arabia, India and Pakistan, according to officials and an N.S.A. map that indicates sites of what the agency calls “computer network exploitation.”
“What’s new here is the scale and the sophistication of the intelligence agency’s ability to get into computers and networks to which no one has ever had access before,” said James Andrew Lewis, the cybersecurity expert at the Center for Strategic and International Studies in Washington. “Some of these capabilities have been around for a while, but the combination of learning how to penetrate systems to insert software and learning how to do that using radio frequencies has given the U.S. a window it’s never had before.”