Firefox 2.0.0.6 fixes yet another protocol handling bug

But some argue it's all the fault of a poorly designed Windows API

Mozilla late Monday updated the Firefox browser for the second time this month to patch a pair of vulnerabilities, including yet another flaw in how it parses malformed URLs that can call up other applications.

Firefox 2.0.0.6 includes a fix for a bug disclosed by a pair of researchers a week ago, said Mozilla head of security Window Snyder. This reduces the risk of malicious data being passed through Firefox to another application that may then trigger unexpected and potentially dangerous behavior," said Synder on a Mozilla blog.

The update was the latest move in a skirmish between Firefox and Microsoft Corp.'s Internet Explorer (IE) users that began three weeks ago Tuesday.

Then, Danish researcher Thor Larholm spotted what he said was a critical input-validation bug in IE. He argued that it let the browser pass potentially malicious URLs to other programs, including Firefox. He staked out the position that IE was to blame, while other security experts said it was Firefox's fault. Last Monday, Snyder acknowledged that Firefox was just as guilty as IE. "We thought this was just a problem with IE," she said. "It turns out, it is a problem with Firefox as well."

But the blame may ultimately rest not on Firefox or IE, but on Windows itself, according to an advisory posted by US-CERT. In a warning issued last week, the federally supported vulnerability tracking center pinned responsibility on Windows, saying that the operating system "fails to properly handle protocols specified in a URI, which could allow a remote, unauthenticated attacker to execute arbitrary commands on a vulnerable system."

Changes in how Windows parses uniform resource identifiers (URI) were made by IE 7, US-CERT continued, portioning some blame to the Microsoft browser. However, the root of the problem is in Windows' ShellExecute application programming interface (API), according to US-CERT.

Danish bug tracker Secunia ApS also pegged Windows as the culprit.

Mozilla's own "2007-027" advisory spelled out its position on the part Microsoft Windows plays in the vulnerability. "Since this handling is a property of the Windows Shell API, this variant appears to affect other Internet-enabled applications that pass these URIs to the Windows Shell," it read.

But because the API remains, cautioned the advisory, it's impossible to know whether the fix in Firefox 2.0.0.6 will protect in every situation. "A way to exploit a common handler with a single unexpected URI as an argument may yet be found," the warning said.

Microsoft did not immediately reply to questions about the ShellExecute API, and whether it would be fixed, if it was in fact flawed.

The second vulnerability patched by 2.0.0.6 was a bug rated "moderate" that involved certain Firefox add-ons that create about:blank Web pages.

The Firefox update can be downloaded from the Mozilla site; current Firefox 2.x users can also use the browser's built-in automatic update feature to patch their browsers.

Join the PC World newsletter!

Error: Please check your email address.

Our Back to Business guide highlights the best products for you to boost your productivity at home, on the road, at the office, or in the classroom.

Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Gregg Keizer

Computerworld
Show Comments

Essentials

Microsoft L5V-00027 Sculpt Ergonomic Keyboard Desktop

Learn more >

Lexar® JumpDrive® S57 USB 3.0 flash drive

Learn more >

Mobile

Lexar® JumpDrive® S45 USB 3.0 flash drive 

Learn more >

Exec

Lexar® Professional 1800x microSDHC™/microSDXC™ UHS-II cards 

Learn more >

HD Pan/Tilt Wi-Fi Camera with Night Vision NC450

Learn more >

Lexar® JumpDrive® C20c USB Type-C flash drive 

Learn more >

Audio-Technica ATH-ANC70 Noise Cancelling Headphones

Learn more >

Budget

Back To Business Guide

Click for more ›

Most Popular Reviews

Latest News Articles

Resources

PCW Evaluation Team

Azadeh Williams

HP OfficeJet Pro 8730

A smarter way to print for busy small business owners, combining speedy printing with scanning and copying, making it easier to produce high quality documents and images at a touch of a button.

Andrew Grant

HP OfficeJet Pro 8730

I've had a multifunction printer in the office going on 10 years now. It was a neat bit of kit back in the day -- print, copy, scan, fax -- when printing over WiFi felt a bit like magic. It’s seen better days though and an upgrade’s well overdue. This HP OfficeJet Pro 8730 looks like it ticks all the same boxes: print, copy, scan, and fax. (Really? Does anyone fax anything any more? I guess it's good to know the facility’s there, just in case.) Printing over WiFi is more-or- less standard these days.

Ed Dawson

HP OfficeJet Pro 8730

As a freelance writer who is always on the go, I like my technology to be both efficient and effective so I can do my job well. The HP OfficeJet Pro 8730 Inkjet Printer ticks all the boxes in terms of form factor, performance and user interface.

Michael Hargreaves

Windows 10 for Business / Dell XPS 13

I’d happily recommend this touchscreen laptop and Windows 10 as a great way to get serious work done at a desk or on the road.

Aysha Strobbe

Windows 10 / HP Spectre x360

Ultimately, I think the Windows 10 environment is excellent for me as it caters for so many different uses. The inclusion of the Xbox app is also great for when you need some downtime too!

Mark Escubio

Windows 10 / Lenovo Yoga 910

For me, the Xbox Play Anywhere is a great new feature as it allows you to play your current Xbox games with higher resolutions and better graphics without forking out extra cash for another copy. Although available titles are still scarce, but I’m sure it will grow in time.

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?