Browser enforced web application security; IE8 safest?

microsoft internet explorer 8 logoWith a notoriously bad reputation for security (or the lack thereof) in Internet Explorer, Microsoft claims to have invested a lot in IE8 security in general and specifically in browser enforced website security. Indeed, according to the product site, IE8:

[…] helps protect you from today’s threats, including malware and phishing, as well as emerging threats that can compromise your computer without your knowledge. Other browsers either don’t offer you this level of protection or require you to download and configure third-party add-ons to get it, but with Internet Explorer 8 you get it right out of the box, and turned on by default.

And in August Microsoft proudly pointed to results of a (MS commissioned) study by NSSLabs, which stated that IE8 blocked 81% of malware download attempts vs. 27% for FF3 (and even less for other browsers) and 83% of phishing attacks vs. 80% for FF3 (and 54% for Opera 10 and less for Chrome and Safari).

So there you have it, IE8 is the safest browser around, no? Well, that would be jumping to conclusions; IE8 still has it’s fair share of browser security issues (but don’t they all) and the dreaded security-hole called ActiveX is still supported as well. Let’s just focus at how IE8 tries to protect you from malicious websites and compare that functionality with what the competition has to offer.

Smartscreen Filter

Smartscreen filter is the name for the Microsoft technology that uses an “in-the-cloud reputation database” which is contacted by the browser to assess the trustworthiness of a URL. Using that information, access to dangerous sites and downloads of malware can be blocked. The system is very similar to Google Safe Browsing that is implemented in Firefox, Chrome and Safari, but Smartscreen seems to be better in stopping malware from being downloaded. On the other hand the 2nd NSSlabs-study deemed both as effective when it comes to blocking access to phishing sites. Based on these (MS sponsored) results one could conclude that IE8 might have an advantage over the competition, but I for one would be very interested in an updated version of these tests with cooperation from the other browser-makers.

XSS-filter

IE8’s XSS-filter offers protection against type1 cross-site scripting attacks. Although it offers no protection against (less common) type0 and type2 xss-attacks, the mere fact that IE8 does offer out of the box XSS-protection is a big thing. Except … except apperantly there’s a serious bug in IE8’s XSS-filter, that can be abused to do cross-site scripting. Microsoft has not yet confirmed or fixed the bug,¬† leading some sites (e.g. Google) to disable the XSS-filter by adding “X-XSS-Protection: 0” to the http response header. Now isn’t that ironic?

Clickjacking defense

Microsoft also included clickjacking defense in IE8, by letting website owners define whether or not their pages are allowed to be included in (i)frames. This can be done by simply adding “x-frame-options” to the http response header with values “deny” to deny a page from being shown in any frame and “sameorigin” to limit framing to pages from the same domain. x-frame-options however does not protect against clickjacking with flash or other embeds.

But where’s the competition?

So what’s available in Firefox, Chrome and Safari apart from the Google Safe Browsing implementation? Nothing much up until now, I’m afraid …

At Mozilla smart guys are working on “Content security policy“. CSP is a declarative server-driven anti-XSS framework, with policies being pushed through HTTP headers. Although the policy may require non-trivial website changes because inline scripts will be disallowed by default, it certainly has potential (to the extend Microsoft is said to be interested). But CSP is not there yet, now is it?

Over at Google, engineers are including (type1) XSS-protection and support for the Strict Transport Security spec (forcing a browser to load a site only over HTTPS by issuing an http response header) in the dev-channel builds of Chrome 4. As some may have noticed while looking for Google Talk’s chatback badge last week, x-frame-options (as anti-clickjacking measure) has already been implemented in Safari4 and Chrome3 as well. So especially Google is trying to make some serious progress, but Chrome 4 can hardly be considered granny-ready, can it?

That leaves us Firefox with the NoScript extension, but I’ll come back to that combination in a minute.

IE8 the safest browser?

OK, this might hurt, but let’s give credit where credit is due; IE8 indeed seems to offer the best out of the box protection against malicious websites. It is the only browser to come with good phishing- and malware-blocking (Smartscreen) combined with (limited and currently broken) protection against some types of XSS and clickjacking-attacks. So thank you Redmond for setting the example!

The only alternative: Firefox + NoScript

Firefox does not offer the out of the box protection IE8 does, but when combined with the NoScript extension, it really is the only readily available alternative (Lynx not withstanding). NoScript offers superior protection against XSS, clickjacking and a host of other threats.

Even if you’re only vaguely security-conscious, installing Firefox and NoScript should really be your first choice. Depending on the level of protection you want, you can use the default but disruptive whitelist configuration (which blocks all javascript and flash) or switch to the less secure “Allow scripts globally” mode. But whatever configuration you choose, anti-XSS and clickjacking protection are always enabled.

It really is beyond me why NoScript’s Clearclick and anti-xss aren’t in Firefox by default, especially since they seem complementary to CSP, as they’re barely disruptive for a novice user and (last but not least) as Mozilla could easily one-up Microsoft this way? Anyone?

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