The SolarWinds hack may have included 1,000 Russian state-backed operatives, according to new information released by Microsoft president Brad Smith. Smith gave an interview over the weekend in which he argued that the SolarWinds breach was the largest and most sophisticated cyberattack to date. Smith added that 4,000 lines of Orion update code were rewritten to help the hackers achieve their end goal, requiring a lot of manpower.

Smith stated that, at Microsoft, more than 1,000 engineers worked on the cyberattacks and mitigating the subsequent risks the tech giant faced after being targeted by the Russian hackers. This led Smith to believe that the number of attackers behind the incident was much larger than previously thought. Smith also claimed that despite the potentially large number of adversaries, the attackers have an asymmetric advantage in avoiding detection.

Read More: 1000+ Hackers Worked on SolarWinds Campaign, Microsoft Says