MS plugs IE phishing bug

Breaks monthly cycle

Microsoft has broken its monthly release cycle to issue a cumulative patch designed to address three potentially serious security vulnerabilities.

The company has dropped support for a common Web authentication method to fix a flaw which made it easier to lure IE users to malicious constructed or fraudulent sites.

Support is removed for handling user names and passwords in HTTP or HTTPS URLs in IE.

The syntax http(s)://username:password@server/resource.ext has legitimate users but is also frequently used in phishing scams.

The problem is compounded by a security vulnerability, resolved with yesterday’s cumulative update, which could be exploited to display a fake URL in the address and status bars of IE.

Rather than fix that specific flaw, which first emerged almost two months ago, Microsoft is ditching an entire approach. Microsoft alerted developers that it was contemplating the change last week.

Good riddance to bad coding

Reg reader response since has fallen into two camps: those who think the use of user names and passwords in HTTP should never have been supported; and others who think a pop-up dialogue box should be generated when URLs containing authentication tokens are used.

This would take the form: "Warning: You are about to go to xyz.com. Please check this address carefully to make sure that it is the site you were expecting to visit."

And another (two) things...

The cumulative patch - critical for IE 5.01, 5.5 and 6.0 users - also contains fixes for two other security vulnerabilities.

These involve an Internet Explorer File Download Extension Spoofing flaw and a Cross Site Scripting vulnerability, as explained in greater depth here.

Although Microsoft made a decision to release patches on a monthly basis last October it always retained the option of releasing urgent fixes on an ad-hoc basis.

Concern that the 'faking it' flaw - which emerged in early December - could aid the cause of fraudsters has driven the issue further up Microsoft's security agenda. A fix for the flaw was not released earlier in order to allow testing, Stuart Okin, Chief Security Officer at Microsoft UK, recently told El Reg. The phishing problem is much bigger an issue than an IE flaw which might allow a fake URL to be displayed in the address and status bars of visiting Web surfers, he said.

Too serious to wait

Microsoft went to monthly updates with the idea that if the release of fixes was more predictable more companies would get into the habit of consistently applying patches. Failure to apply patches is a major cause of corporate insecurity.

Critics might say Microsoft is releasing its fix - which it admits it critical - in a way that (by its own logic) means the patch is less likely to be rapidly applied.

It's all a bit of a mess and reason enough for some to consider using alternative browsers, though we can't see much of a stampede in that direction anytime soon.

In the meantime, IE users are urged to review Microsoft's patch here. ®

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