EMB ERJ 170/175 ER/LR
Inflight Event / Encounter Wake Vortex Encounter; Inflight Event / Encounter Weather / Turbulence
General None Reported / Taken
Environment - Non Weather Related; Procedure
Descending through approximately 28;000 FT aircraft hit clear air turbulence; but possible wake turbulence; [which] 'abruptly' rolled the aircraft to a 60-70 degrees bank to the left followed by severe turbulence. Flight Attendant stated it lifted the galley cart off the ground; which caused a drink to spill [on] a passenger. [We] immediately slowed aircraft from 300 KTS through 270 KTS. There were no clouds; traffic; nor any reports of this on the BULLZ arrival. MFD was set on expanded traffic with a 12.5 mile range. We could have been possibly following a heavy 777. No one was hurt and a report was given to Air Traffic Control after he questioned our speed being different than assigned.
ERJ-170 Captain reported a possible wake vortex encounter on arrival to ORD.