How Browser History Sniffing Works
Browser history sniffing is nothing new however continues to prompt debate; is it a black-hat, white-hat or grey-hat technique at identifying specifics of visitors to Websites? Browser history sniffing uses JavaScript and CSS (or Python) to identify Sites that the visitor has been to. This information may then be used for a multitude of purposes including customising the content of a page based on what the Browser history tells us about the visitor.
How does Browser History Sniffing work?
Go to a Webpage that has hyperlinks where you have clicked on some of those hyperlinks. You’ll notice that links to Websites that you have visited are coloured differently to those you haven’t visited. This is very handy and is achieved through CSS working with your Web Browser; your Browser remembers Sites you have visited and if it comes across a link that you have visited in the past it’ll change the colour of the link text based on the colour specified in the CSS.
Browser history sniffing basically runs URLs through the browser history and if the colour of the link changes (i.e. it is indicated that the link has been visited), this affirmation is returned and may be acted upon by further JavaScript, PHP or other scripting. Of course, inferences may be made about a visitor based upon the data of Sites they have visited.
How Browser History Sniffing can Boost Sales
To illustrate the power of browser history sniffing, let’s assume we are a new and used car dealer. We stock all sorts of cars from sports cars to family wagons, from luxury to very basic. We have a Website listing all of the cars we have available to sell, each car with its own URL and the home page listing the deals of the day (we have to choose something to go on the home page!). The problem is that the bounce rate from the home page is high; the deals of the day on the home Page just isn’t working.
We therefore get an SEO expert in. The SEO guru implements a Script that compares the top few thousand most visited Websites against the visitors Browser history. Added to this is some statistical analysis of the Sites in the list to be compared against the Browsers history e.g. if a visitor has visited Conde Nast Traveller, Playboy Magazine and Fortune Magazine Online we have a better than even chance that the visitor is male and has a bit of money to spend and would probably prefer a new than used car.
How we can use this script is as follows; say a visitor has visited the Volvo homepage, a few baby name Websites and a Maternity wear websites we can assume that the person is looking for a safe family oriented car. The browser history sniffer script runs very quickly so as the visitor lands on our car website we can gather and analyse their browser history and then customise the homepage for cars they are likely to be interested in. In the past our ‘family oriented’ visitor as identified above would land on a generic Page listing deals that may be of no interest to the visitor. Now however we are able to show the visitor a Page showing the latest Volvo wagons which greatly improved the click through rate.
Is Browser History Sniffing Black-Hat SEO?
In the previous example there is likely a benefit to both the Website owner and the visitor; the Website owner increases sales whereas the Visitor gets more relevant information. This is therefore white-hat SEO. There is also no negative implication for either party.
Where Browser history sniffing becomes dangerous and unethical is where the Browser history is used for phishing and malware purposes; a Browser history sniffing script may be used to identify people who may be more prone to phishing scams and then targeted. All sorts of information about your Browser may be attained via various scripts and combining this with a history of Sites you visit may be of much value to hackers and criminals.
What are the Browsers doing about History Sniffing
The big problem for browsers is that storing history and displaying previously visited Sites is very useful for users. The browsers therefore can’t simply ‘switch off’ the history functionality. The good news is that the major browsers are taking (or have taken) steps to address this; Read more about whatw Firefox and Apple Safari are doing about this.
Are you Vulnerable to History Snigging?
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