Suddenly our hosting company complaint our boss with a google mail that saying something like:
Your site is full of spam/scam. Please remove such malicious thing or we will unlist your site.
That made us crazy. We found some links in our WordPress site is taking us to a page, that is obviously NOT our site-page. But with the same URL of our page (domain/my-page) it's showing someone other's contents - that's disturbing too.
We tried the cPanel's "Virus Scanner" to find any trace of virus attack to the site, but found nothing.
Then, one of our developer found a way to generate a new page for the content of that page with a slightly different slug, and that worked. But after days it's worthless.
How can we get rid of such spam/scam?