The Dark Side of Search Engine Optimization (SEO): Using CSS to hide spam links
Passive malware on page / off screen (OPOS) or dark stealth links, and How to Avoid Being abused by black hat hackers optimization
I have discovered by accident, during a routine page source check, some "alien" code lines. A mix of regular HTML links and a couple of lines of tracking Java script, placed in the php header, indicating that a black hat SEO hacker broke in. The hack was simple and efficient, using CSS to keep the links on the page and visible for search engines but off the screen and invisible to human users. A
multiple search engines comparative search
using goScout.com on this subject does offer information but not much comfort. To test some of the web page link spam detection tools I could find I placed three spam links on the top middle and bottom of the test page but none was detected as potential spam (see the references section for links to some sites).
There was no noticeable difference between the hacked page and the regular page and the intrusion was not detected for months probably. The links were place on page but moved outside the screen or display area ("on page / off screen" placement or OPOS link). This is the HTML code of the hacked page
We decided to try to reproduce the hack on a test page, and sure enough we got a perfect on page / off screen (OPOS) "dark link", on the page at minus 650 pixels (-650px). No horizontal scroll bars, no sign of the text even if is fairly long.
This attack might explain why our site
Ghidul Medical
basically disappeared from Google index for a couple of months at the beginning of 2010
read the full article here:
Passive malware, on page / off screen (OPOS) or stealth dark links, and how to avoid being abused by black hat optimization hackers by Octavian P Jurma
ProSD.com & MetaProductions.com
Optimizare Web Site
via
prosd.com
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The Dark Side of Search Engine Optimization (SEO): Using CSS to hide spam links Passive malware, on page / off screen (OPOS) or stealth dark links, and how to avoid being abused by black hat optimization hackers Excerpt: I have discovered by accident, during a routine page source check, some "a ...
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