Virus? A profile permission window popped up after I add a new contact

Are you on a wireless network when this happens? If so, that wireless network has probably been hacked, and is trying to send you to a different site when you try to load content from webdav.facebook.com. If not, you probably have bigger problems, as it's probably a compromise of your cellular carrier.

Also if you have logged into Facebook via your iPhone and have included Facebook friends with your contacts it will try to add your new contact to Facebook. If there is a problem with accessing the proper port on your router this message can occur.

Noctis wrote:

Is it virus or what?

No, it's not a virus.

I'm unfamiliar with using Facebook from an iPhone, because I generally avoid Facebook. However, it sounds like deggie has experience with this message, so I would pay attention to his suggestion.

However, if that's not the issue in your case, this looks like something dishonest is going on, probably on the network level.I can't read the Chinese in your screenshots, but if the certificate your phone is using for webdav.facebook.com actually belongs to www.hracky-4kids.cz, that's a serious problem. If that's the case, and since you were not connected to a wifi network at the time, other people using your cellular carrier should be having the problem. Using a VPN could solve the problem.

I receive like 20 of these messages everyday, and it seems like I'm far from the only one in China. The problem appears to be widespread among iOS users in China since the beginning of the year. Some sort of malicious software, or the authorities somehow messing up with Facebook. Does anyone have any idea of how to make the wretched messages stop? It's really annoying.

If this is a problem with your cellular service provider snooping on your data, that's not something Apple can help you with. If you are able to do so (no idea whether the GFW will allow it), using a VPN based outside China would help. Something like Freedome, from Finland-based F-Secure, would be good:

https://itunes.apple.com/app/f-secure-freedome-vpn/id771791010

However, I believe I may have read somewhere that the GFW may prevent this kind of thing. Beyond that, this is outside my area of expertise... I know very little about the GFW and Chinese government snooping, and how to circumvent those things.

Noctis wrote:

Thanks for your recommendation, I'm using a chargeable VPN service actually.

Ahh, if you are already using a VPN, that's actually the likely source of the problem. Stop using the VPN and see if the problem disappears.

I just realized that I even don't have Facebook installed in my iPhone...

iOS 8 includes direct support for Facebook, without needing the Facebook app. In addition, the "webdav.facebook.com" address suggests that server is a webdav calendar server. I'm not familiar with it, so I'm not sure what it's used for, but other apps (such as Calendar) are involved in connecting to webdav servers.