(Reuters) - Microsoft Corp has notified 60 customers that their data was likely compromised in the suspected Russian hacking campaign centered on Texas-based software firm SolarWinds Corp, the company’s president told U.S. lawmakers on Tuesday. In prepared remarks, Microsoft’s Brad Smith told the U.S. Senate Select Committee on Intelligence that the company believed some of the methods the hackers used to break into target networks have yet to be made public and that “the attacker may have used up to a dozen different means of getting into victim networks during the past year.” A top U.S. cyber official said earlier this month that nine federal agencies and 100 private-sector companies had been affected by the hack, which first came to light in December. Smith said that several other organizations – including unidentified foreign government agencies – had also been breached.