Buses and light rail cars make San Francisco's "Muni" fleet the seventh largest mass transit system in America. But yesterday its arrival-time screens just displayed the message "You Hacked, ALL Data Encrypted" -- and all the rides were free, according to a local CBS report shared byRAYinNYC:Inside sources say the system has been hacked for days. The San Francisco Municipal Transportation Agency has officially confirmed the hack, but says it has not affected any service... The hack affects employees, as well. According to sources, SFMTA workers are not sure if they will get paid this week. Cyber attackers also hit Muni's email systems.