Now that Windows 7 is available, a recent blog by Chester Wisnieski (who works at security vendor Sophos), entitled Windows 7 vulnerable to 8 out of 10 viruses, which has stirred some interest.

Here's a quick summary for those who missed Chester's blog. During a test SophosLabs conducted, they subjected Windows 7 to "10 unique [malware] samples that arrived in the SophosLabs feed." They utilized a clean install of Windows 7, using default settings (including the UAC defaults), but did not install any anti-virus software. The end result was 8 of the 10 malware samples successfully ran and the blog proclaims that "Windows 7 disappointed just like earlier versions of Windows." Chester's final conclusion? "You still need to run anti-virus on Windows 7." Well, we agree: users of any computer, on any platform, should run anti-virus software, including those running Windows 7.

Clearly, the findings of this unofficial test are by no means conclusive, and several members of the press have picked apart the findings, so I don't need to do that. I'm a firm believer that if you run unknown code on your machine, bad things can happen. This test shows just that; however, most people don't knowingly have and run known malware on their system. Malware typically makes it onto a system through other avenues like the browser or email program. So while I absolutely agree that anti-virus software is essential to protecting your PC, there are other defenses as well.

Let me recap some of the Windows 7 security basics. Windows 7 is built upon the security platform of Windows Vista, which included a defense-in-depth approach to help protect customers from malware. This includes features like User Account Control (UAC), Kernel Patch Protection, Windows Service Hardening, Address Space Layout Randomization (ASLR), and Data Execution Prevention (DEP) to name just a few. The result, Windows 7 retains and refines the development processes, including going through the Security Development Lifecycle, and technologies that made Windows Vista the most secure Windows operating system ever released.

Beyond the core security of Windows 7, we have also done a lot of work with Windows 7 to make it harder for malware to reach a user's PCs in the first place. One of my favorite new features is the SmartScreen Filter in Internet Explorer 8. The SmartScreen Filter was built upon the phishing protection in Internet Explorer 7 and (among other new benefits) adds protection from malware. The SmartScreen Filter will notify you when you attempt to download software that is unsafe - which the SophosLabs methodology totally bypassed in doing their test.

So while I'm not a fan of companies sensationalizing findings about Windows 7 in order to sell more of their own software, I nevertheless agree with them that you still need to run anti-virus software on Windows 7.  This is why we've made our Microsoft Security Essentials offering available for free to customers. But it's also equally important to keep all of your software up to date through automatic updates, such as through the Windows Update service. By configuring your computers to download and install updates automatically you will help ensure that you have the highest level of protection against malware and other vulnerabilities.

User Account Control is one of those Windows features that evokes a number of different responses from folks. Most people appreciate the enhanced security UAC offers, but we did hear complaints about the high number of UAC prompts in Windows Vista. This led some customers to turn off UAC, which concerns us from a security perspective. So in Windows 7, we've given a great deal of thought to how we marry enhanced security with ease-of-use. We have written extensively about the changes in UAC for Windows 7 on the Engineering Windows 7 blog (Post 1, Post 2, Post 3, Post 4).

Now, Technical Fellow Mark Russinovich weighs in on UAC with some great insight on the technology and some of our motivations around the decisions we have made. Check out Inside User Account Control now available online from TechNet Magazine.

Two Windows 7 testers claim they've found a second glitch in the Windows 7 beta's default security configuration that could let malware automatically elevate itself to full administrative privileges without triggering User Account Control prompts or even shutting down UAC at all.

Last week, Microsoft (NSDQ:MSFT) bloggers Long Zheng and Rafael Rivera published simple proof-of-concept code that automatically disables UAC in Windows 7 without any user interaction. On Wednesday, Zheng and Rivera published details on a second UAC flaw in the Windows 7 beta that stems from the OS being set up to automatically elevate Microsoft-signed applications and code in order to minimize UAC alerts.

The problem, according to Zheng, is that some of these trusted, Microsoft-signed applications are designed to execute third-party code for legitimate reasons, which allows attackers to create malware that exploits their trusted status.

"Unfortunately, this flaw is not just a single point of failure. The breadth of Windows executables is just too many and too diverse, and many are exploitable," Zheng wrote.

Microsoft denied that the first UAC flaw was actually a flaw, claiming that the only way UAC could be changed without the user's knowledge was if malicious code was already running on the box.

Microsoft is still investigating the second UAC flaw, said a spokesperson who declined to comment further. However, both Zheng and Rivera reported hearing rumors that the second UAC issue has been fixed in internal Windows 7 builds.

To illustrate the potential impact of the second UAC flaw, Rivera published a proof-of-concept that could let attackers use rundll32.exe -- one of the Microsoft-signed applications -- to execute malicious code on a PC with full administrative privileges.

Zheng recommended that Windows 7 beta users set their UAC settings to 'high' in order to minimize the danger for both flaws. However, that makes UAC in the Windows 7 beta behave in the same overly chatty fashion it did in Vista, which once again highlights the difficulty of balancing security and usability concerns.

While Windows 7 is expected to hew to the same high security standards as Vista, security experts are watching Microsoft's response to the UAC issues closely, and some are beginning to take issue with how the software giant is responding to the UAC reports.

Microsoft is denying that there is a security hole in the User Account Control (UAC) feature of Windows 7 after a blogger reported it last week and posted what he said was a fix for it.

"I can tell you that this is not a vulnerability," a spokesman for Microsoft through its public relations team said in an e-mail.

Last week, Long Zheng, a long-time Microsoft watcher and blogger, wrote on his I Started Something Blog that a change Microsoft made in Windows 7 to improve the UAC security feature has left the new OS less secure because it allows someone to remotely turn the feature off without the user knowing.

Zheng said that the new UAC default setting, which does not notify a user when changes are made to Windows settings, is where the security risk lies. A change to UAC is seen as a change to a Windows setting, so a user will not be notified if UAC is disabled, which Zheng said he was able to do remotely with some keyboard shortcuts and code.

However, Microsoft is standing by the change to UAC's default setting, saying it was the result of "a great deal of usability feedback on UAC prompting behavior," and that the feature cannot be exploited unless there is already malicious code running on the machine and "something else has already been breached."

"The intent of the default configuration of UAC is that users don't get prompted when making changes to Windows settings," the spokesman said. "This includes changing the UAC prompting level."

UAC has been a controversial feature since Microsoft introduced it in Windows Vista to improve its security and give people who are the primary users of a PC more control over its applications and settings. The features prevents users without administrative privileges from making unauthorized changes to a system.

Because of how it was set up in Vista, UAC sometimes -- through a series of screen prompts -- prevents even authorized users from being able to access applications and features they should normally have access to. Microsoft vowed it would make changes to the feature to make it more user-friendly in Windows 7.

Windows 7 has been in public beta for about a month and not expected to ship until early next year. However, Microsoft said Friday the next release of the OS would be a nearly final release candidate and not another beta release, so some believe it will be out before the end of 2009.

C. Slide the slider bar to the lowest value (towards Never Notify), with description showing Never notify me. 



D. Click OK to make the change effective.


E. Restart the computer to turn off User Access Control.[Via DigitalLife]