Microsoft's New Patch Tuesday Model Comes With Benefits And Risks

Microsoft as of this month officially transitioned its Patch Tuesday model to a cumulative patching process for Windows 7 and Windows 8.1 that security experts say is a more flexible and streamlined way to update vulnerable systems. But it also comes with some risks.

October 11 marked the first time Microsoft released updates via its new system, which combines security and non-security fixes into large bundles. Three distinct update bundles will roll out each month; two available to enterprise customers, and one for consumers.

On the second Tuesday of each month, otherwise known as Patch Tuesday, Microsoft will distribute two update batches.

One of these, for businesses and consumers, is released via Windows Update, Windows Server Update Services (WSUS), and the Windows Update Catalog. This is a monthly rollup of security and non-security fixes, which contains all updates for the month as well as fixes for the previous months. If a user skips a month, they will receive the patches for that month in the following month's bundle.

The second bundle contains all security patches for the specific month and excludes fixes from previous months. These security-only rollouts, intended for enterprise users, are distributed through WSUS and Windows Update Catalog.

"What Microsoft is trying to do is make things simpler for users by delivering all updates together," explains Amol Sarwate, director of vulnerability labs at Qualys. "When administrators install patches, they can just deploy one patch." This model also makes it easier to learn which fixes are included and which aren't, he adds.

On the third Tuesday, Microsoft will release a preview of non-security updates slated to arrive in the following month's rollup. This allows businesses to test updates on their systems and verify compatibility.

Sarwate explains how this new strategy is intended to streamline the update process for enterprise customers and give them the option to choose specific bundles. He advises organizations to take advantage of the opportunity to test new updates ahead of their release.

Microsoft's new update model also addresses problems businesses previously encountered when applying new security fixes.

"The main issue in the past has been that some users, mostly by mistake, didn't install all patches," explains Johannes Ullrich, dean of research at SANS Technology Institute. "This led to a very fragmented user base and increased the risk of new patches, as you couldn't be sure that all old patches were applied correctly."

Business systems are more tightly managed, he continues, and decisions are more carefully made as part of a controlled patch process. Organizations can delay patches for a particular month if they conflict with business-critical apps.

The Tradeoffs

While the change is intended to make patching simpler for enterprise users, experts agree there is still risk involved. 

"As someone who manages patching, I welcome the change," says Michael Gray, VP of tech at Thrive Networks. "The time spent researching every patch is exhaustive."

However, he continues, there is a risk of people not wanting to download these monolithic updates. What's more, the larger these bundles get, the more likely it is someone could compromise the entire package.

Ullrich acknowledges the new model will make patch application easier, but there is also risk related to availability.

"If a particular patch interferes with a particular function of the PC, either a hardware component or customer software, then the entire patch has to be delayed and it will not be advisable to just apply a partial patch," he explains. 

This further emphasizes the importance of patch testing, which may be a bit easier on the new system since there will be less variability, he continues. However, it remains to be seen how this will work out in the first few months of Microsoft's new model.

As IT managers begin to roll out these changes, they should keep standard patching best practices in mind, says Sarwate. He recommends deploying updates in waves, so if there's a need to roll back, it's only necessary for a small group of workers.

Ullrich advises corporations to apply patches as soon as Microsoft releases them. Home users should still automatically apply patches.

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