Page hijacking is a form of spamming the index of a search engine (spamdexing). It is achieved by creating a rogue copy of a popular website which shows contents similar to the original to a web crawler, but redirects web surfers to unrelated or malicious websites. Spammers can use this technique to achieve high rankings in result pages for certain key words.

Page hijacking is a form of cloaking, made possible because some web crawlers detect duplicates while indexing web pages. If two pages have the same content, only one of the URLs will be kept. A spammer will try to ensure that the rogue website is the one shown on the result pages.

Case Study: Google Jacking

One form of this activity involves 302 server-side redirects on Google. Hundreds of 302 Google Jacking pages were said to have been reported to Google. While Google has not officially acknowledged that page hijacking is a real problem, several people have found to be victims of this phenomenon when checking the search engine rankings for their website. Because it is difficult to quantify how many pages have been hijacked, GoogleJacking.org was founded in May 2006 to help make Google aware of the significance of Google Jacking. Visitors can add themselves to a map, providing a visual indicator of how widespread the problem is.

Example of Page Hijacking

Suppose that a website offers difficult to find sizes of clothes. A common search entered to reach this website is really big t-shirts, which - when entered on popular search engines - made the website show up as the first result:SpecialClothes
Offering clothes in sizes you can't find elsewhere.
www.example.com/

A spammer working for a competing company then creates a website that looks extremely similar to one listed and includes a special redirection script that redirects web surfers to the competitor's site, but shows the page to web crawlers. After several weeks, a web search for really big t-shirts then shows the following result:SpecialClothes
Offering clothes in sizes you can't find elsewhere... at better prices!
www.example.net/
- Show Similar Pages -

Notice how .com changed to .net, as well as the new "Show Similar Pages" link.

When web surfers click on this result, they are redirected to the competing website. The original result was hidden in the "Show Similar Pages" section.