Spammers are conspired through the site Rambler

Today, walking through the pages of Vkontakte, I came across a page of one “girl” on whom she was agitating to go to a new and cool dating site. Everything seems to be mundane and uninteresting if not for the link. And the link was:

h ttp: //vkontakte.ru/away.php? to = http% 3A% 2F% 2Fplus.rambler.ru% 2Flogin.html% 3Fback% 3D% 2522
% 253E% 253C% 252Ftable% 253E% 253Cscript% 253E
location.href% 253D% 2527http% 2527% 252B% 2527
% 253A% 252F% 252Frta% 2527% 252B% 2527neta% 2527
% 252B% 2527xxx% 2527% 252B% 2527.ru% 252F% 253Fid
% 2527% 252B% 2527ent% 253D430% 2527% 252B% 252749
% 2527% 253C% 252Fscript% 253E% 253C% 2521

Next, the actual clarification begins. Those who are familiar with the site vkontakte.ru knows that this site before going on an external link throws the user to the page vkontakte.ru/away.php which warns the user that it is not safe to follow the external link. Thus, clicking on the link we get to the internal page of Vkontakte where we see the following:

You are leaving the site VKontakte.ru on the external link h ttp: //plus.rambler.ru/login.html? Back =% 22% 3E% 3C% 2Ftable% 3E% 3Cscript% 3Elocation.href% 3D% 27http
% 27% 2B% 27% 3A% 2F% 2Frta% 27% 2B% 27neta% 27% 2B% 27xxx% 27% 2B% 27.ru% 2F% 3Fid% 27% 2B% 27
ent% 3D430% 27% 2B% 2749% 27% 3C% 2Fscript% 3E% 3C% 21 provided by one of the participants. Administration VKontakte.ru is not responsible for the content of the site plus.rambler.ru and strongly recommends that you do not indicate any of your data related to VKontakte.ru (especially e-mail, password and cookies) on third-party sites.

In addition, the site plus.rambler.ru may contain viruses, trojans and other malicious programs that are dangerous for your computer. If you have no serious reason to trust this site, it is best not to go to it, even if you allegedly received this link from one of your friends.

If you have not changed your mind, click on h ttp: //plus.rambler.ru/login.html? Back =% 22% 3E% 3C% 2Ftable% 3E% 3Cscript% 3Elocation.href% 3D% 27http
% 27% 2B% 27% 3A% 2F% 2Frta% 27% 2B% 27neta% 27% 2B% 27xxx% 27% 2B% 27.ru% 2F% 3Fid% 27% 2B% 27
ent% 3D430% 27% 2B% 2749% 27% 3C% 2Fscript% 3E% 3C% 21.
If you do not want to risk the security of your account and computer, click cancel.

And then if you decode this link from url_encode in utf, then we get a normal link:

h ttp: //plus.rambler.ru/login.html? back = ">

Here everything is more or less clear. For example, if you go to h ttp: //plus.rambler.ru/login.html? Back = habrahabr, then in the code you can find the following line:

input type = "hidden" name = "back" value = " plus.rambler.ruhabrahabr "

That is the line

h ttp: //plus.rambler.ru/login.html? back = ">

just injects into the site plus.rambler.ru a third-party script that throws the user onto the planetaxxx site.
What is it done for? The simple question is most likely done because Vkontakte keeps track of all external links and clears all spam, but the beauty of the approach amazes me more and the fact that the Rambler did not bother to do a normal check of external variables is even more striking.
At the moment I do not know whether this entails any serious vulnerabilities. Now I try to find out, therefore, wrote this habratopik. What do people say?