The global launch of Microsoft's next-generation Windows 7 operating system today was greeted with fanfare -- and some grumbling from security professionals who worry the new OS already has too many holes.

Windows 7, which has been broadly beta-tested for many months, is hailed as being easier to use than its predecessor, Vista, which didn't catch on the way many industry watchers had expected. But if the new environment is easier on the user, then it isn't as secure as it could be, security professionals say.

First, there is the issue of vulnerabilities. Microsoft has patched several security flaws in Windows 7 since last November, and a zero-day exploit of vulnerabilities in Microsoft's Server Message Block (SMB) technology affected both new and old versions of Windows last month. The SMB vulnerabilities were patched in the most recent round of upgrades last week.

Even as Microsoft fixed the SMB problem, it revealed on Patch Tuesday that another vulnerability, a flaw in Windows CryptoAPI, could allow spoofing. That vulnerability was rated "important" in the most recent round of patches.

"[Windows 7] has a great look and feel and is overall much smoother than Windows Vista, while at the same time improving on its security measures," says Wolfgang Kandek, CTO of security vendor Qualys. "However...consumers should hit the 'Update' button once it is installed. Software security is such a dynamic space -- with monthly updates, in the short time that it takes to get a product finished, packaged, and delivered, multiple security [advisories] have been produced. For example, Windows 7 was affected by five of the 13 security advisories that Microsoft published in October's Patch Tuesday."

While most security experts were not surprised by the vulnerabilities that have already turned up in Windows 7, some continue to complain that the implementation of Microsoft's User Access Control feature in the new OS could create even more security problems than were seen in Vista.

In a nutshell, experts say, Windows 7 makes it easier for users to turn off or ratchet down the capabilities of UAC to make the new OS easier to use. Unlike Vista, which required a special utility to change UAC settings, Windows 7 enables administrators to simply turn off or reduce security prompts that are designed to warn users they are about to do something risky.

In fact, the default configuration of Windows 7 continues to give users administrative privileges and doesn't set the UAC controls on maximum. As a result, IT administrators will have to change settings on Windows 7 PCs if they want to get the full benefit of UAC -- or if they want users to run the so-called "standard" configuration, in which the end user doesn't not have admin privileges.

"It's kind of a time bomb," says Eric Voskuil, CTO at BeyondTrust, which makes tools that help enterprises manage user privileges. "In the default configuration, the UAC slider is in the second position, which is insecure. There's a reason you don't want to turn off those prompts, but Windows 7 actually makes that easier."

By simplifying the user's ability to change UAC controls, Microsoft might also have made it easier for hackers to distribute malware to Windows 7 PCs, experts say.

"Increasing operating system usability also increases security risks -- risks of infection and compromise of data and functionality," says Ray Dickenson, CTO of Authentium, another security tool vendor. "The changes to Windows 7 UAC have made it easy for malware writers to turn UAC off entirely -- without the user's knowledge."

Long Zheng, a security researcher, published a proof-of-concept back in June that exploits the UAC flaw. Microsoft says it doesn't consider the UAC settings to be a vulnerability, and the company has stated it has no intent to change the UAC feature.

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