Suspects, believed to be "Russian hackers", have compromised emails of officials working in the European and Eurasian affairs bureau and East Asian and Pacific affairs bureau at the US State Department, but the classified network does not appear to have been accessed, the news outlet reported, citing a third official.
The State Department used the software and was reportedly among those affected.
A State Department spokesperson refused to provide any details, citing security reasons, noting that the department "takes seriously its responsibility to safeguard its information and continuously takes steps to ensure information is protected".
According to Politico, the attack shows the scope of the US government data allegedly accessed by Russian hackers was larger than previously known to the public, which, in turn, raises concerns about the department's cybersecurity.
American officials said Russian hackers were likely to blame for the SolarWinds hack. The New York Times reported, citing unnamed US government sources, that the Joe Biden administration planned “clandestine actions across Russian networks” as a response to the breach.
Moscow has denied all allegations of being involved in the attack, stressing that no evidence has been provided by Washington to back up its allegations. The Kremlin also issued a statement saying that the reported US plans to hit Russian networks in response to the breach were “alarming” and would effectively amount to “international cybercrime”.