The unprovoked crime occurred at about 7:30 a.m. in the lower-level parking structure at the mall in the 200 block of North Glendale Avenue, police said.
"The suspect was standing next to several bags and appeared to be smoking narcotics when the victim walked by,'' police said in a statement. "The suspect quickly walked up to the victim and struck her in the side of the head with (his or her) right hand.''
The woman kept walking, and the suspect walked away from her. Police released security images of the suspect, who is of unknown gender, about 5-feet-4 inches to 5-feet-7 inches tall, with a medium build.
Anyone with information on the case was urged to call police at (818) 548-4911 or Crime Stoppers at (800) 222-TIPS.