A website and blog by Peter Lewis




I was looking around on the Internet for something today, using Google, as I frequently do, but when clicking on a link, instead of the page itself, Google served me up this:

Google warning

[click on the image to see it full-size]

The basic premise, it seems, is that Google believes that this domain contains something that might be dangerous to me, and therefore won't show it. How long has Google been doing this kind of filtering, and on what bases will it filter sites out?

Assuming that perhaps Google's legal team was worried about providing links to sites which might contain trojans and the like, I just went ahead and copied the link directly into Firefox's address bar.

Unfortunately, at this stage I was met with the following screen:

Firefox warning

Okay, so now something weird's going on, I thought. Why on earth isn't my browser doing what I tell it to? Who does it work for anyway? This isn't what I signed up for.

Let's assume that the Firefox developers thought that this was a useful function, which should be enabled by default. More importantly however, where is Firefox getting its information from? From Google, perhaps?

This then got me to thinking what's going on behind the scenes. I haven't checked the Firefox source code to see (though thank goodness that I can), but I can't imagine that it retains a static list of sites to give warnings about. Rather, I'd imagine it checks with a remote server to see if the site I'm trying to view is on some kind of blacklist. So, does this mean that every time I direct Firefox to a web page, it compares this against a list on some remote server somewhere? Is the information about every page I view being sent to Mozilla, or worse Google? Even those which I don't reach through Google?

I've no idea, but I don't like this.

And yes, I could "just disable it" I'm sure, but that misses the point. This "functionality" is enabled by default, and both Firefox and Google appear to be colluding to blacklist certain domains (the above warning was specific to the domain, not the page). This is a massive amount of power to wield.

I'd appreciate some clarity on this, if anyone can volunteer some.

Thanks for the links. It seems that the local copy of Firefox does indeed maintain a list of blocked sites, which is updated from Google every 30 minutes! So, I guess that allows them to track when your're running Firefox or not.

Also, Firefox will send information (including cookies) to Google every time you find a "bad" site.

Luckily it can be disabled in Edit -> Preferences -> Security.

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