Feeds

Microsoft to issue emergency patch for ASP.Net vuln

Muzzling 'padding oracle' for good

Boost IT visibility and business value

Microsoft will release an emergency patch on Tuesday that plugs a security hole in a variety of its web developer tools that has been under active attack for more than a week.

The vulnerability in ASP.Net applications allows attackers to decrypt password files, cookies, and other sensitive data that is supposed to remain encrypted as they pass from the server to a web browser. It works by flooding a server with thousands of corrupted web requests and then analyzing the error messages and other responses that result. The series of responses are known as a “cryptographic padding oracle” that over time deliver information that an attacker can deduce the secret key used to scramble the communications.

The vulnerability was disclosed two weeks ago at the Ekoparty conference in Argentina. Microsoft soon responded with an advisory that warned that the vulnerability was under “limited attack.” It recommended that users implement several temporary measures to make the exploits harder to carry out.

The workaround involves reconfiguring a webserver so that all error messages are mapped to a single error page that prevents the attacker from distinguishing among different types of errors, effectively muzzling the oracle. Thai Duong, one of the researchers who disclosed the vulnerability, has said turning off customized error messages isn't enough to prevent exploits, because attackers can still glean important clues by measuring the different amounts of time required for certain errors to be returned.

Tuesday's out-of-schedule update will be available at about 10 am Pacific time and initially will be available only on the Microsoft Download Center. It will eventually be released through the Windows Update and Windows Server Update services.

Microsoft's next regularly scheduled patch release is October 12. Curiously, the vulnerability being patched by the out-of-band release is rated “important” the second-highest rating on Microsoft's four-tier severity scale. Emergency patches are usually reserved for "critical" flaws.

More from Microsoft is here. ®

Gartner critical capabilities for enterprise endpoint backup

More from The Register

next story
Microsoft: We plan to CLEAN UP this here Windows Store town
Paid-for apps that provide free downloads? Really
Snowden on NSA's MonsterMind TERROR: It may trigger cyberwar
Plus: Syria's internet going down? That was a US cock-up
Who needs hackers? 'Password1' opens a third of all biz doors
GPU-powered pen test yields more bad news about defences and passwords
e-Borders fiasco: Brits stung for £224m after US IT giant sues UK govt
Defeat to Raytheon branded 'catastrophic result'
Hear ye, young cyber warriors of the realm: GCHQ wants you
Get involved, get a job and then never discuss work ever again
Chinese hackers spied on investigators of Flight MH370 - report
Classified data on flight's disappearance pinched
Microsoft cries UNINSTALL in the wake of Blue Screens of Death™
Cache crash causes contained choloric calamity
prev story

Whitepapers

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.
7 Elements of Radically Simple OS Migration
Avoid the typical headaches of OS migration during your next project by learning about 7 elements of radically simple OS migration.
BYOD's dark side: Data protection
An endpoint data protection solution that adds value to the user and the organization so it can protect itself from data loss as well as leverage corporate data.
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?