Researchers estimate that a Wi-Fi attack could take over 20,000 wireless routers in New York City within a two-week period. The researchers theorize that attack would work by guessing administrative passwords and then instructing the routers to install new worm-like firmware which would in turn cause the infected router to attack other devices in its range. The attack could hop from router to router for many miles in some cities like Chicago or New York. New York is particularly susceptible to this type of attack because of its low percentage of encrypted routers.”]
Source: https://www.csoonline.com/article/2122529/a-wi-fi-virus-outbreak–researchers-say-it-s-possible.html