Suspected Chinese hackers exploited a flaw in software made by SolarWinds Corp to help break into U.S. government computers last year, five people familiar with the matter told Reuters, marking a new twist in a sprawling cybersecurity breach that U.S. lawmakers have labeled a national security emergency.
Two people briefed on the case said FBI investigators recently found that the National Finance Center, a federal payroll agency inside the U.S. Department of Agriculture, was among the affected organizations, raising fears that data on thousands of government employees may have been compromised.
The software flaw exploited by the suspected Chinese group is separate from the one the United States has accused Russian government operatives of using to compromise up to 18,000 SolarWinds customers, including sensitive federal agencies, by hijacking the company’s Orion network monitoring software.
Security researchers have previously said a second group of hackers was abusing SolarWinds’ software at the same time as the alleged Russian hack, but the suspected connection to China and ensuing U.S. government breach have not been previously reported.
Reuters was not able to establish how many organizations were compromised by the suspected Chinese operation. The sources, who spoke on condition of anonymity to discuss ongoing investigations, said the attackers used computer infrastructure and hacking tools previously deployed by state-backed Chinese cyberspies.
The Chinese foreign ministry said attributing cyberattacks was a “complex technical issue” and any allegations should be supported with evidence. “China resolutely opposes and combats any form of cyberattacks and cyber theft,” it said in a statement.
A USDA spokesman acknowledged a data breach had occurred but declined further comment. The FBI declined to comment.
Although the two espionage efforts overlap and both targeted the U.S. government, they were separate and distinctly different operations, according to four people who have investigated the attacks and outside experts who reviewed the code used by both sets of hackers.
While the alleged Russian hackers penetrated deep into SolarWinds network and hid a “back door” in Orion software updates which were then sent to customers, the suspected Chinese group exploited a separate bug in Orion’s code to help spread across networks they had already compromised, the sources said.
The side-by-side missions show how hackers are focusing on weaknesses in obscure but essential software products that are widely used by major corporations and government agencies.
The connection between the second set of attacks on SolarWinds customers and suspected Chinese hackers was only discovered in recent weeks, according to security analysts investigating alongside the U.S. government.
Reuters could not determine what information the attackers were able to steal from the National Finance Center (NFC) or how deep they burrowed into its systems. But the potential impact could be “massive,” former U.S. government officials told Reuters.
The NFC is responsible for handling the payroll of multiple government agencies, including several involved in national security, such as the FBI, State Department, Homeland Security Department and Treasury Department, the former officials said.
Records held by the NFC include federal employee social security numbers, phone numbers and personal email addresses as well as banking information. On its website, the NFC says it “services more than 160 diverse agencies, providing payroll services to more than 600,000 Federal employees.”
“Depending on what data were compromised, this could be an extremely serious breach of security,” said Tom Warrick, a former senior official at the U.S Department of Homeland Security. “It could allow adversaries to know more about U.S. officials, improving their ability to collect intelligence.”