Hackers linked to China have accessed more than 400 US Treasury computers, including Janet Yellen’s.

The US Treasury Department announced in a letter back in December that it was the victim of a security breachreferring to an “Advanced Persistent Threat actor sponsored by the Chinese government.” Now we know more about the size of the hack, thanks for reporting and Bloomberg.

The hacking group hacked into more than 400 desktop and laptop computers, many of which he interacted with senior leaders it focused on “sanctions, international affairs and intelligence.” They also found employee usernames and passwords, in addition to more than 3,000 files on unnamed computers. These documents included travel data, organization charts, disciplined tools and external financial metrics.

The agency’s report indicates that the perpetrators may have stolen information about this, but were not able to access the Treasury or emails. Next report, and from Bloombergshows around 50 files were stolen from Treasury Secretary Janet Yellen’s computer. Hackers also found material related to investigations conducted by the Foreign Trade Commission. The committee also examines securities related to the purchase of real estate and foreign investment in the US.

The commission’s report also stated that there was no evidence that the hackers had attempted to hide in Treasury systems for the purpose of gathering intelligence for a long time, and did not abandon the malware.

Investigators say the intrusion was carried out by a well-known Chinese government-sponsored group known as Silk Typhoon, Halfnium or UNC5221. It is said that they did the hacking outside of working hours to avoid detection. Last month, a spokesman for China’s Foreign Ministry accused the attack of being government-sponsored. “absurd and baseless.”

Counterintelligence officials are still in the middle of a “damage assessment” but Treasury officials are expected to brief the Senate Banking, Housing and Urban Affairs Committee on the matter this week.

Update, January 17 2025, 10:47AM ET: This article has been updated to include additional reporting.