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 "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.

Both target sites have high ranks but score low on search engines. A bad sign for our victim site. It means ranks is transferred properly but search engines figured out we are linking to a spam site and dropped us along with them from the rankings. We managed to get back after almost two months of struggles and unhappy customers.

This attack might explain why our site Ghidul Medical basically disappeared from Google index for a couple of months at the beginning of 2010

Some conclusions:

There is a clear need for web page link spam detection tools ideally an add-on that can expose such links similar to the add-ons that can expose "no follow" links

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

 

infoPagina Ghid Medical contine informatii despre

Cabinet Stomatologic Timisoara | recomandari cabinet stomatologic timisoara de calitate cabinet stomatologic timisoara gaseste cel mai bun cabinet sau specialist

Ghidul Medical Ghid Medical Online Index comunitate medicala cabinete medicale Medicina umana si alternativa Medicina dentara Farmacie Psihologie Wellness Medicina veterinara Cabinet medical Timisoara Ghidul Medical Romania

Cabinet Stomatologic Timisoara: Recomandari cabinet stomatologic timisoara de calitate cabinet stomatologic timisoara gaseste cel mai bun cabinet sau specialist