Hi Codeforces Community,
This is my first post and I want to share something I have observed lately.
On a newly loaded page, I see pop ups ads which prevents from interacting with site's content until a sacrificial click on page takes me to pop ads, much like in mirrors of torrent sites. I switched to https page on experimenting and I found that those types of ads doesn't happen there.
I re-installed firefox on my linux machine, and this only happens on codeforces, so I dont suspect any malware on my PC (nor any unknown process).
Is this intentional from Codeforces? Screenshot attached.
Looks like either malware on your PC (not necessarily in Firefox, it may be more complicated) or man-in-the-middle on your internet connection. Some ISPs may do that, especially if you're using a public Wi-Fi.
What happens on other non-https websites, which have you tried?
I looked over every running processes on my Linux Mint and everything looked normal there.
Other http sites works fine, I switched ISP but still everything stays same.
If other CF users are not facing this, then I suspect the plugins for CodeForces (CF Predictor, Competitive Companion) may be causing this, just like: Google Ads
Sure, any browser plugins (even non CF-related) can do that. Please try disabling them or running Firefox in Safe Mode. Also note that it's possible that author didn't expect ads to show up at all.
If it shows up on http version of the site only, that is most likely man in the middle. Are you using VPN, there could be a malware on router as well.
The url shows mobpushup.com (bottom left). This url appears to be associated with many malware/adware (Source: grindsoft).