Feeds

MS insists bodged fix didn't spawn Windows crash risk

Teardrop Explodes

Seven Steps to Software Security

Microsoft has denied claims that an unpatched flaw in a file and printer sharing feature was inadvertently introduced when it fixed an earlier, less severe problem in the software back in December 2007.

Redmond patched a medium severity flaw in the same Server Message Block (SMB) version 2 functionality within Vista nearly two years ago. Unfortunately, in the process, it allegedly created a much more serious flaw that meant systems running Vista, pre-R2 versions of Windows Server 2008, and earlier versions of Windows 7.

Vulnerable systems can be crashed with only a single malformed packet, according to Laurent Gaffié, the security researcher who discovered the so-called Teardrop attack.

Gaffié claims to have tracked back the latter problem to changes Microsoft made in resolving a flaw in SMBv2 signing nearly two years ago (via MS07-063.mspx).

"The only thing I know regarding this 'patching' process is, when they fixed this code, they opened another bigger, worse security issue," Gaffié told Security Focus.

Microsoft denied suggestions that the earlier patch might be responsible for its latest security pickle. "We researched this claim by the researcher and confirmed this vulnerability was not introduced by MS07-063," said Christopher Budd, security response communications lead for Microsoft.

Redmond earlier acknowledged that, whatever its origins, the SMB flaw is real. As well as posing a system crashing risk, the flaw also poses a code injection danger. Security researchers separately warn that the flaw could lend itself to the creation of network worms.

Pending the availability of a fix from Microsoft, users are advised to apply either apply firewall defences (Block TCP ports 139 and 445) or disable SMBv2 as possible workarounds, as explained in an advisory by the software giant here. ®

Mobile application security vulnerability report

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
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
Mozilla fixes CRITICAL security holes in Firefox, urges v31 upgrade
Misc memory hazards 'could be exploited' - and guess what, one's a Javascript vuln
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

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.
How modern custom applications can spur business growth
Learn how to create, deploy and manage custom applications without consuming or expanding the need for scarce, expensive IT resources.
Reducing security risks from open source software
Follow a few strategies and your organization can gain the full benefits of open source and the cloud without compromising the security of your applications.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
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.