IT Pro is supported by its audience. When you purchase through links on our site, we may earn an affiliate commission. Learn more

Microsoft rushes to patch critical flaw affecting every Windows PC

Bigger than Heartbleed, vulnerability means users need to download patch now

Flaw fix

Microsoft has been forced to issue a critical patch for a vulnerability that affects every current version of its Windows operating system.

The bug affects code in the Microsoft secure channel (schannel) security component. This component implements the secure sockets layer and transport layer security (TLS) protocols.

A flaw in the code means it fails to properly filter specially formed packets allowing hackers to execute code remotely on an affected Windows machine.

According to the advisory, the flaw affects Windows Server 2003, Windows Vista, Windows Server 2008, Windows 7, Windows 8/8.1, Windows Server 2012/2012 R2, and Windows RT/RT 8.1 machines. The flaw is rated critical for all affected operating systems. 

Microsoft said that it "had not received any information to indicate that this vulnerability had been publicly used to attack customers". 

Security researchers said exploitation of the SChannel bug has the potential to be worse than Heartbleed and Shellshock combined due to the large numbers of affected systems. 

"Heartbleed was less powerful because it was just' an information disclosure bug and Shellshock was remotely exploitable only in a subset of affected systems," said Craig Young, security researcher at Tripwire.

"Some administrators may want to prioritise this over the Internet Explorer patch even though we've seen attacks we've seen in the wild against the browser. This is because MS14-066 has the potential to be exploited without user-interaction," he said. 

Young added that exploitation of the bug would be "tricky". "Hopefully, this will give admins enough time to patch their systems before we see exploits."

Just last week, Microsoft was preparing a slew of updates to its products with 16 patches to fix critical flaws in Windows and Internet Explorer.

Featured Resources

Four strategies for building a hybrid workplace that works

All indications are that the future of work is hybrid, if it's not here already

Free webinar

The digital marketer’s guide to contextual insights and trends

How to use contextual intelligence to uncover new insights and inform strategies

Free Download

Ransomware and Microsoft 365 for business

What you need to know about reducing ransomware risk

Free Download

Building a modern strategy for analytics and machine learning success

Turning into business value

Free Download

Recommended

Microsoft warns of new botnet variant targeting Windows and Linux systems
Security

Microsoft warns of new botnet variant targeting Windows and Linux systems

16 May 2022
Windows Server admins say latest Patch Tuesday broke authentication policies
Server & storage

Windows Server admins say latest Patch Tuesday broke authentication policies

12 May 2022
Actively exploited Windows vulnerability reaches peak severity when paired with popular attack
Security

Actively exploited Windows vulnerability reaches peak severity when paired with popular attack

11 May 2022
Microsoft announces new business security services led by in-house experts
enterprise security

Microsoft announces new business security services led by in-house experts

9 May 2022

Most Popular

Windows Server admins say latest Patch Tuesday broke authentication policies
Server & storage

Windows Server admins say latest Patch Tuesday broke authentication policies

12 May 2022
Costa Rica declares state of emergency following Conti ransomware attack
ransomware

Costa Rica declares state of emergency following Conti ransomware attack

10 May 2022
16 ways to speed up your laptop
Laptops

16 ways to speed up your laptop

13 May 2022