Can a virus take up residence in an ADSL modem?

Question

Malware

I bought a computer for relatives in the village.
After a while I come to visit and find that on some pages, some sites there are clickers, which definitely cannot be there (for example, on Yandex).

He swore that somewhere they picked up a virus. I checked my computer with three antiviruses - it's clean.
I don't know why the suspicion arose in me that everything is not so simple here. Bring your personal computer. I connect to the modem - the same garbage, on some pages of some sites there are clickers.
Moreover, the pages on which clickers appear differ on two computers (for example, on one computer the clicker appears on video.yandex.ru, on the other on pogoda.yandex.ru).

The clickander code is embedded directly into the body of the page (for example, as in this picture - it is loaded from the site pop. spy4 .in ) get a new username/password. After that, everything seems to be fine for now. The question is, what could it be? I have only 2 options - a virus in the modem itself, or one of the employees of Rostelecom "makes some money" in the hope that "whoever in the village will pay attention to this" (but I don't know how technically and organizationally this is possible).

Answer 1

Look at the dns settings on the computers and on the router. Perhaps there is something completely alien and harmful

Answer 2

Modem viruses do exist, such as Psyb0t . Always change the default login and password to more complex ones, especially if it's admin/admin, etc.