IE9 pips Chrome, Firefox and Safari in blocking attacks

18 Jul 2011

Microsoft’s Internet Explorer 8 and 9 in-house reputation system beat rival browsers, such as Apple’s Safari, Google’s Chrome and Mozilla’s Firefox, in an independent test to see which could best block social-engineering attacks.

According to Microsoft, the independent test run by NSS Labs which rated the browsers against a sample set of European malware URLs over 19 days in April, held that IE 8 achieved a mean block rate of 90pc, leaving Chrome 10, Firefox 4 and Safari 5 at 13pc each.

Opera, which uses technology from antivirus company AVG, came in last at 5pc.

When assessing IE 9 with application filtering turned on, the results were even more dramatic, taking that version to a mean blocking rate of 100pc.

Microsoft says Internet Explorer’s positive showing appears to be thanks to two embedded technologies. Smartscreen URL Filter is a cloud-based system that checks URLs against a master database. This is present in both IE 8 and 9 and seems to work more or less identically in both.

In addition, IE 9 has added a second system, SmartScreen Application Reputation, which on the basis of this test offers browser users a remarkably effective level of download block protection. Chrome, Firefox and Safari all use a rival URL checking system, Google’s Safe Browser Feed, which as previous NSS Labs tests have suggested, is now falling some way behind.

“The significance of Microsoft’s new application reputation technology cannot be overstated. Application Reputation is the first attempt by any vendor to create a definitive list of every application on the internet,” the authors conclude.

“Browsers provide a layer of protection against socially-engineered malware, in addition to endpoint protection products; as this report shows, not all are created equal. The overall lower protection offered by Firefox, Safari and Chrome is concerning.”

Response times for blocking malware

An extra but important dimension also tested was the ‘average response time to block malware’, basically, the time it took each browser to add a problem site to the block list once it had been fed into the test by NSS Labs.

Again, IE 9 with Application Reputation enabled gained a perfect score, adding a site without any delay, the only browser to manage such a feat. Interestingly, however, without the Application layer, IE 8 and 9 sank down the table, taking nearly 14 and 16 hours respectively, behind Safari’s five hours, Chrome’s nearly seven hours, and Firefox’s 8 hours.

Block time is worth paying attention to because the longer protection takes to be activated, the longer the window of possible exposure.

The limitation of the report is that it is only measuring one dimension of the threat users face when using browsers, that of attacks where the user can be tricked – ‘socially-engineered’ in security parlance – into downloading malware. This compares with what are called ‘drive-by’ attacks that seek to exploit specific vulnerabilities in software and which require no user intervention.

Which is more dangerous is a matter of debate, although NSS Labs references a separate study by AVG that found socially-engineered attacks to be the most likely way for malware to find its way onto a user’s PC.

A social-engineering attack has the advantage that it recruits the user to agree to a download event, thereby potentially bypassing Windows controls such as User Access Control (UAC) and even the warnings of antivirus software. A drive-by attack, especially one manipulating a zero-day flaw, can sneak onto the PC without any of these defences being aware but requires more engineering effort to work.

The claim that socially-engineered attacks are the more significant doesn’t entirely accord with the admittedly patchy evidence that exists.

A recent and revealing assessment by Qualys using its Browsercheck tool found that large numbers of browser users routinely run out-of-date plug-ins for interfaces such as Flash Adobe Reader and especially Java. Many of these have significant flaws that can be attacked by drive-by exploits. 

It could be that both sides of this coin – social-engineering attacks and drive-by attacks – are equally perilous but in different ways.

A final qualification is that the test was conducted on Firefox 4, since supplanted by the rapid-development replacement, version 5.0, likewise Google Chrome, which has reached version 13. The URL-filtering systems used by these are, however, the same as in the previous versions so would be unlikely to make a difference to their blocking performance.

John Kennedy is a journalist who served as editor of Silicon Republic for 17 years