Feeds

Tiny typo blamed for massive IE security fail

That'll teach you to keep your ampersands in order

Using blade systems to cut costs and sharpen efficiencies

One small typo in Microsoft's code caused the security vulnerability that prompted Microsoft to release an out of sequence patch on Tuesday, it has emerged.

A rogue ampersand ("&") created a security hole in a the MSVidCtl ActiveX control that hackers began exploiting early this month. A blog posting on Microsoft's Security Development Lifecycle (SDL) by Michael Howard, a security program manager at Microsoft, explained that the minor typo corrupted the code used by the ActiveX control. This in turn created a buffer-overflow bug, he explains.

The extra ‘&’ character in the vulnerable code causes the code to write potentially untrusted data, of size cbSize, to the address of the pointer to the array, pbArray, rather than write the data into the array, and the pointer is on the stack. This is a stack-based buffer overrun vulnerability.

Microsoft's Visual Studio development tool uses the same Active Template Library (ATL) code, prompting Microsoft to issue an update for its coding tools at the same time as pushing out an update for IE.

Howard explained that the flaw was of a type that made it difficult to spot during code review. "In the SDL we require that teams fuzz their controls, but our fuzzing tools didn’t find this because the method in question requires a specially formed input stream that includes many sentinel bytes," Howard explained.

Microsoft plans to update its fuzzing tools so that they are better at detecting this kind of error. It will also mandate the use of newer ATL code.

The cause of the vulnerability was originally pinpointed by reverse engineer Thomas Dullien (aka Halvar Flake), chief exec of Zynamics, and security researcher Dennis Elser. A blog posting discussing the issue and its possible ramifications can be found here. As the researchers note, the flaw is particularly troublesome because third-party applications that make use of the buggy ATL library are also rendered vulnerable to attack. ®

The smart choice: opportunity from uncertainty

More from The Register

next story
Yorkshire cops fail to grasp principle behind BT Fon Wi-Fi network
'Prevent people that are passing by to hook up to your network', pleads plod
HIDDEN packet sniffer spy tech in MILLIONS of iPhones, iPads – expert
Don't panic though – Apple's backdoor is not wide open to all, guru tells us
NEW, SINISTER web tracking tech fingerprints your computer by making it draw
Have you been on YouPorn lately, perhaps? White House website?
LibreSSL RNG bug fix: What's all the forking fuss about, ask devs
Blow to bit-spitter 'tis but a flesh wound, claim team
Black Hat anti-Tor talk smashed by lawyers' wrecking ball
Unmasking hidden users is too hot for Carnegie-Mellon
Attackers raid SWISS BANKS with DNS and malware bombs
'Retefe' trojan uses clever spin on old attacks to grant total control of bank accounts
Manic malware Mayhem spreads through Linux, FreeBSD web servers
And how Google could cripple infection rate in a second
Don't look, Snowden: Security biz chases Tails with zero-day flaws alert
Exodus vows not to sell secrets of whistleblower's favorite OS
prev story

Whitepapers

Seven Steps to Software Security
Seven practical steps you can begin to take today to secure your applications and prevent the damages a successful cyber-attack can cause.
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.
Designing a Defense for Mobile Applications
Learn about the various considerations for defending mobile applications - from the application architecture itself to the myriad testing technologies.
Build a business case: developing custom apps
Learn how to maximize the value of custom applications by accelerating and simplifying their development.
Consolidation: the foundation for IT and business transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.