China has been particularly active, the official said, part of a national strategy to target the U.S.
The foreign spy agencies use a massive database analysis to combine and cross-reference information obtained from cyberattacks on targets ranging from the Office of Personnel Management
to the cheating website Ashley Madison
to identify and potentially compromise operatives.
"Individually, the OPM breach and the Ashley Madison breach both present significant dangers to U.S. personnel, including intelligence personnel, but taken together, they really ratchet up the level of harm," said Marc Zwillinger, a lawyer handling data breach and privacy cases. "The OPM breach has confidential information about U.S. personnel and people that have applied for security clearances, and the Ashley Madison breach reveals people's most intimate secrets about the affairs they might be having, and together, it provides a lot of leverage that could be used to blackmail and possibly influence U.S. personnel."
Both Russia and China use non-government entities, including hacking groups and private companies, to infiltrate U.S. systems and analyze the collected data. The intention, the U.S. official says, is to hide the true source of the attacks. However, the U.S. official says both governments also carry out cyberattacks using their own assets and attempt to cover their tracks using other methods.
Such cyberattacks have been on a gradual upswing since the mid-2000s due in large part to their success, the official said. The Obama administration has repeatedly acknowledged the threat.
"We're confronting a persistent and dedicated adversary. The threat is ever-evolving. And it is critically important for us to make sure that our defensive measures that are intended to prevent these kinds of intrusions reflect that ever-evolving risk," White House press secretary Josh Earnest said in June.
U.S. government agencies not responding to threat
However, internal reports have repeatedly found that U.S. government systems remain vulnerable. Many U.S. government agencies still lack urgency in addressing the problem, leaving U.S. systems open to further attacks. The U.S. official described as "likely" the prospect of additional successful cyberattacks on sensitive U.S. government systems.
"What the OPM breach really revealed is that government cybersecurity isn't even up to the par of the private sector, and the private sector suffers security breaches all the time," said Zwillinger. "So it's a wake-up call both for the government networks and commercial networks."
Some lawmakers, as well as current and former intelligence officials, have spoken about the possibility of retaliatory attacks raising the costs on states targeting the U.S.
"We need to do a better job of protecting our systems. The best offense is a good defense. But I also think we can go beyond that and explore ways to deter future attacks," California Rep. Adam Schiff said Tuesday.