Feeds

Redmond security guru explains IE vuln miss

The one that got away

Secure remote control for conventional and virtual desktops

A Microsoft insider has posted an explanation for the firm's failure to spot a critical flaw in Internet Explorer that obliged the firm to publish an out-of-sequence patch earlier this month.

Michael Howard, a principal security program manager with the software giant, explains that the flaw cropped up in a blind-spot developers weren't trained to scour for potential flaws. Human error is always a factor in developing secure code and sometimes fuzzing tools can help unearth error. Unfortunately, in this case, testing tools weren't up to the job either.

Howard explained that the flaw involved a "time-of-check-time-of-use" bug in how Internet Explorer handles data binding objects. "Memory-related [time-of-check-time-of-use, or TOCTOU] bugs are hard to find through code review," Howard writes in a post to Microsoft's Security Development Lifecycle blog. "We teach TOCTOU issues, and we teach memory corruption issues, and issues with using freed memory blocks; but we do not teach memory-related TOCTOU issues."

Automated tools that throw a range of tests data at applications in order to look for problems also came unstuck, he adds.

"In theory, fuzz testing could find this bug, but today there is no fuzz test case for this code. Triggering the bug would require a fuzzing tool that builds data streams with multiple data binding constructs with the same identifier. Random (or dumb) fuzzing payloads of this data type would probably not trigger the bug, however."

Microsoft's security testers plan to update their testing methodology in order to look more closely for the class of vulnerability exploited by the recent IE flaw. Howard's technically literate post goes on to explain how defences built into Vista and Server 2008 mitigated against the bug. The post, which provides coding examples, illustrates the inherent problems of security testing, an issue developers well away from Redmond are obliged to grapple with every day. ®

The essential guide to IT transformation

More from The Register

next story
Microsoft boots 1,500 dodgy apps from the Windows Store
DEVELOPERS! DEVELOPERS! DEVELOPERS! Naughty, misleading developers!
Apple promises to lift Curse of the Drained iPhone 5 Battery
Have you tried turning it off and...? Never mind, here's a replacement
Mozilla's 'Tiles' ads debut in new Firefox nightlies
You can try turning them off and on again
Linux turns 23 and Linus Torvalds celebrates as only he can
No, not with swearing, but by controlling the release cycle
Scratched PC-dispatch patch patched, hatched in batch rematch
Windows security update fixed after triggering blue screens (and screams) of death
prev story

Whitepapers

5 things you didn’t know about cloud backup
IT departments are embracing cloud backup, but there’s a lot you need to know before choosing a service provider. Learn all the critical things you need to know.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Backing up Big Data
Solving backup challenges and “protect everything from everywhere,” as we move into the era of big data management and the adoption of BYOD.
Consolidation: The Foundation for IT Business Transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?