Wordpress site is appears clear of malware, but clicking on Google search results redirects to spam sites - wordpress

Question

An issue was brought to me involving malware on a WP environment. When I search the brand in Google and click the corresponding link, I'm redirected to a 3rd party spam site.
This has been happening for a while (over a week), but my site hasn't been put on Google's blacklist. Additionally, site scanners like , Norton Safeweb, etc. all claim the site isn't compromised.
Additional details:
I found and deleted some suspicious PHP eval() functions and then did a search and replace in my pages and database for any remaining code. After the site cleared into un-blacklisted status with Google I thought it was all over, ran updates and took numerous measures to protect the site from future infection.
However the issue still persists.

Answer 1

Were the nameservers ever changed by the malware or attackers? Google could have the wrong DNS information for your domain and thinks its hosted at said spam site? Resubmit your site to Google or report the issue to them to resolve (may also be resolved automatically next time Google tries to crawl your domain)?
It is a strange issue I have not seen before either, have you looked at your .htaccess file in the root directory? It is also possible that this has a rewrite condition that if the referrer is Google to redirect you to the spam site.

Answer 2

Solved this issue. At the time when this happened, this redirect attack was fairly new.
HTTP requests from visitors who passed referrer data from Google Search or Bing were being redirected, some of the time.
By targeting only those coming in from search, the webmaster or site owner is less likely to see the issue (until informed by a third party), while still manipulating a decent amount of the traffic (50% of traffic for most sites comes from search engines).
When I originally posted this question in 2012, this attack was new and because the redirect was being served server-side (directly in a lone PHP file, not via .htaccess), malware signatures from scanners didn't detect this.
Running Maldetect (with an updated database) was the best way to quarantine this issue and analyze the extent of the damage caused by malware.

Answer 3

This issue seems due to wp-vcd Malware that creates rogue WordPress admin users and injected spam links. I faced the similar issue and it got resolved after following these steps.
The files you should check for and delete:
wp-feed.php
wp-vcd.php
wp-tmp.php
Multiple copies of class.theme-modules.php, and
remove a bunch of code from the start of all the functions.php files.
For details you can find on this issue at following links...
https://wordpress.org/support/topic/wp-feed-php/
http://labs.sucuri.net/?note=2017-11-13
http://labs.sucuri.net/?note=2017-11-13