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Firefox 2.0: happier browsing, but secure?

The jury's still out

By Thomas C Greene, 30 Jan 2007

Review It's long past time to bother telling anyone how much better than IE Firefox is. Faster, smaller, more responsive, with tabbed browsing and useful extensions galore. It's also lot more secure than IE, partly because it's open source, and particularly because it's not integrated with the underlying OS.

Firefox's security bugs involve the browser only, and can be fixed quickly and without much fuss. On the other hand, because of its integration with the OS, IE's bugs can involve the system overall, and may need weeks or months to sort out.

Indeed, IE6 was estimated to be vulnerable to exploitation for 284 days last year, even among users who patched it religiously, as we reported recently. In contrast, Firefox was estimated to have left users exposed to unpatched flaws for a total of nine days over the same period. Microsoft's sluggish turnaround with IE's flaws, due chiefly to the vast complexity of the system of which it is a part, is reason enough to recommend Firefox.

Nevertheless, I've long advised security-conscious users to prefer Mozilla to Firefox, in stubborn defiance of the slobbering media infatuation lavished on Firefox. The good news is that recent versions of Firefox are catching up with Mozilla nicely, although there is still some work to be done.

For example, I never liked the way earlier versions of Firefox handled passwords and form data, third party cookies, third party images, cookie expiration, link prefetching, and other configuration issues that affect privacy and security. I also never cared for the way configuration options would change from release to release. It's hard to write about Firefox with an emphasis on security and privacy, or give practical configuration advice, because the developers keep adding configuration options, then discarding them, then reviving them. Mozilla has remained consistent in its excellent set of configuration options, which means that the step-by-step security and privacy setup for Mozilla detailed in my 2004 manual Computer Security for the Home and Small Office is still effective.

Firefox has not shown anything approaching this degree of consistency. For example, on my trusty Linux box, I have Firefox version, with a configuration option enabling me to block third party images. On my cursed Windows box, I have Firefox version, which lacks this option. It's an important privacy issue, because there are invisible, 1-pixel-square images called web bugs often embedded in web pages by third parties - marketing outfits, usually - which are used to track our web sessions. Marketers prefer to call them "web beacons", but they are, in fact, bugs.

They can be defeated quite easily, by preventing your browser from loading images from sites other than the one you are visiting. Perhaps defaults to loading images only from the websites you visit, but by withdrawing the option, the developers have left me a good deal less confident.

Nevertheless, there have been significant improvements in Firefox 2.x. I am somewhat in favour of the option to clear personal data, which you can configure to clear your browser cache, cookies, browsing history, download history, saved form information, passwords, and authenticated sessions. You can choose any or all of those options, and you can set it to delete this information whenever you close Firefox, or you can do it manually. You can also set it to ask you on exit, and choose not to clear these items whenever that suits you.

Still, I have reservations. This is hardly a secure way to delete these data traces, so no one should allow themselves to get a false sense of security from this option. However, if these files are constantly overwritten each time you open and close the browser, it's at least fairly likely that old data will be overwritten in time, and will not accumulate over long periods. It's better than nothing, but it is something of a privacy gimmick and I'm not behind it wholeheartedly.

The right way to do it is to empty and then write-protect each file or directory containing your browser's data (this is far easier to accomplish with Mozilla and Firefox than with IE, by the way, because the 'zilla products don't stash browser traces in the Windows Registry or scatter them about the disk; all of the relevant files and directories are in the user's Moz/FF main directory). Follow that with a proper wipe of your disk's free space, and you'll be in good shape.

Of course, if you do purge and write protect your browser's various history/cache traces, you must not log in routinely as the administrator or root, because such high user privileges will override write protection. It's best first to do the data purging and write protecting for each user as root or the admin, and then to run your browser from a user account thereafter. This way, there simply will be no browser data written to disk, which is the only way to be truly secure and private.

If you're privacy conscious, but concerned about browser slowdown when the cache is unavailable, here are two tips that will help:

First, Javascript is a significant drain on system resources. It's also little more than a gimmick in most instances: I think that fewer than 10 per cent of sites using it actually benefit from it. Its chief purpose is to enrich web developers by giving them something to charge extra for, and I personally loathe it. If you're a little low on system resources, turn off Javascript and your browser will become significantly more responsive. Pages will load faster, you'll see fewer advertisements, and popups will go away altogether. It takes only a second to enable it for those few sites where it's actually useful (it's also more secure to surf this way, since a significant number of exploits, and often the most harmful ones, depend on scripting).

Second, you should know that much of what slows a web page loading is the simple job of drawing it on your screen. So if you've been giving thought to buying a better graphics card, here's another reason to get it. A good graphics card will improve your surfing speed noticeably if your system is a little underpowered.

Back to the privacy issue. Now, in addition to having no option to block third party images, as Mozilla has, Firefox has no option to prevent link prefetching, again, as Mozilla has. Now, perhaps Firefox doesn't do prefetching, but without an option addressing it, one has no idea. Prefetching uses a browser's idle time to cache content that one might be interested in. When you elect to follow a link, the content is in your cache already and loads faster. It's not the best thing for data hygiene, although I should note that if you've emptied and write-protected the cache, it's less of an issue, because there is no place for prefetched content to go except memory (which, under some conditions, could be written to your swap file). In any event, if you're privacy conscious, it's always best for you to decide what content your browser should access, and not let it be done automatically.

This is not to say that Mozilla is flawless. One particularly galling bit of behaviour is the way Mozilla Mail can keep your cookies active after you've closed the browser. If you've set all cookies to expire at the end of the browser session, you mustn't forget that Mozilla Mail has to be closed too, or the session might not really be over. And if you've got Mozilla Mail minimised to a little tray craplet, you might well forget that it's running. You could have a session with your bank, or from a very private web mail account, remain active, and the next person using the browser might be confronted with a lot more information than you'd ever want them to have.

Firefox doesn't have this problem because it's a stand-alone application, so there's less overlap between Firefox and the Thunderbird email client than there is between Mozilla and Mozilla Mail. However, Mozilla users can avoid the problem simply by using Thunderbird or another client in place of Mozilla Mail (personally, I use Linux with the Mozilla browser and with Kmail, which I find immensely more secure and configurable than either Mozilla Mail or Thunderbird).

In spite of this little cookie irritant, I still consider Mozilla slightly more secure than Firefox, although I will allow that I used to regard Firefox as absolutely unsuitable from a security and privacy perspective. It's come a long way, and is now only marginally inferior to Mozilla, which, as just noted, is hardly perfect. Nevertheless, Mozilla remains potentially the most secure browser available - assuming you take the time to configure it well. Firefox is a close second, and I would no longer advise anyone to avoid it.

I would like to see an option to block third party images and an option to prevent prefetching, and I'd like to see a little disclaimer along with the option to clear personal data, since it's hardly secure, although it is certainly better than nothing. And Firefox really has come along nicely in terms of privacy and security features. I sense that it won't be long before I'll be recommending Firefox in favour of Mozilla. Not today, certainly, but soon, very soon. ®

NOTE: Do not, under any circumstances, inform me of what I already know can be done with the about:config menu. Most people are not power users. These settings need to be available in the main, GUI configuration menu. --tcg

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