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May Day! Microsoft's Patch Day is Not Dead… Yet

Corey Nachreiner

Despite Microsoft’s recent Ignite Conference announcement—that they’d no longer follow a monthly patch cycle for Windows 10—Patch Tuesday is in full effect for May. Today, Microsoft released 13 security bulletins, including three Critical ones. If you’re a Microsoft administrator, you should get to these updates quickly.

By the Numbers:

Today, Microsoft released 13 security bulletins, fixing a total of 48 security vulnerabilities in many of their products. The affected products include:

They rate three bulletins as Critical and the rest as Important. As an aside, Microsoft’s main summary post contains a wealth of useful information, including their vulnerability exploitability index, which helps you prioritize the updates based on how dangerous each vulnerability is in the real world.

Patch Day Highlights:

Today’s Patch Day highlights revolve around the Critical rated issues. Most organizations will want to apply the IE update first. Not only does it fix 22 vulnerabilities, but also ones that attackers can leverage in drive-by download attacks, which are one of the most common attacks today.

You should also prioritize the various document related vulnerabilities, since threat actors are increasingly using malicious documents in their spear phishing emails. I recommend you prioritize the Windows Font Driver, Journal, and Office updates as well.

In short, if you apply the updates quickly, in the order Microsoft lists, you’ll do well.

Quick Bulletin Summary:

We summarize the April security bulletins below in order of severity. We recommend you apply the updates in the same order of priority, assuming you use the affected products.

Solution Path:

If you use any of the software mentioned above, you should apply the corresponding updates as soon as you can. I recommend you apply the Critical updates immediately, try to get to the Important ones as a soon as possible.

You can get the updates three ways:

  1. Let Windows Automatic Update do it for you – While patches sometimes introduce new problems, these occasional issues don’t seem to affect clients as often as they do servers. To keep your network secure, I recommend you set Windows clients to update automatically so they get patches as soon as possible.
  2. Manually download and install patches – That said, most businesses strongly rely on production servers and server software. For that reason, I recommend you always test new server updates before applying them manually to production servers. Virtualization can help you build a test environment that mimics your production one for testing.  You can find links to download the various updates in the individual bulletins I’ve linked above.
  3. Download May’s full Security Update ISO –  Finally, Microsoft eventually posts an ISO image that consolidates all the security updates. This ISO conveniently packages the updates in one place for administrators. You’ll eventually find a link to the monthly security ISOs here, but Microsoft may not post it until a few days after Patch Day

For WatchGuard Customers:

Good News! WatchGuard’s Gateway Antivirus (GAV), Intrusion Prevention (IPS), and APT Blocker services can often prevent these sorts of attacks, or the malware they try to distribute. For instance, our IPS signature team has developed signatures that can detect and block many of the attacks described in Microsoft’s alerts:

Your Firebox or XTM appliance should get this new IPS signature update shortly.

Furthermore, our Reputation Enabled Defense (RED) and WebBlocker services can often prevent your users from accidentally visiting malicious (or legitimate but booby-trapped) web sites that contain these sorts of attacks. Nevertheless, we still recommend you install Microsoft’s updates to completely protect yourself from all of these flaws.

As an aside, Microsoft also released two new security advisories today. If you are interested in how Microsoft is improving their cipher suite priority and Flash security, be sure to check their advisory page for those new updates. — Corey Nachreiner, CISSP (@SecAdept)

 

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