Yonhap said Wednesday's outages affected three broadcasters, four banks and two insurance companies.
The three broadcasters -- KBS, MBC and YTN -- reported varying levels of trouble containing the virus. While the networks remained on the air, cable network YTN said editing equipment had been affected and it expected to experience broadcasting problems, Yonhap reported.
Computer networks stopped working entirely at three banks -- Shinhan, Nonghyup and Jeju -- around 2 p.m. Wednesday, Yonhap reported, citing the National Police Agency. Another financial institution, Woori Bank in Seoul, reported it was able to fend off a hacking attack about the same time.
The banks that were affected reported problems with a variety of systems, including Internet banking, ATMs and telecommunication services, and some branches stayed open late because of the slowdown, Yonhap said.