US intelligence agencies said in early January that Russia was likely behind a mass cyberattack on US tech companies and government agencies in December 2020. The attackers used IT management software SolarWinds to gain access.
Russia has repeatedly denied any involvement in the cyberattacks.
The report said on Wednesday, citing a senior official at the cybersecurity firm Mandiant, that the hackers breached several technology firms that provide direct or indirect access to targeted organizations in the United States and Europe.
A US official familiar with the matter told the outlet that the issue has come up in recent National Security Council meetings and federal agencies are monitoring the activity.
Mandiant Senior Vice President Charles Carmakal declined to name the technology providers that were breached, the report said.
The hackers also breached multiple government entities and organizations that work on political and foreign policy matters, the report said. The group is said to have also used new tools and techniques to breach some of their targets this year.
The report said the National Security Agency, FBI, CISA, and the Office of the Director of National Intelligence declined to comment on the matter.