Microsoft’s Last Patch Day Until 2015; Three Critical Patches

It’s that time of the month again; Microsoft Patch Day. Yesterday, Microsoft posted their regular batch of security updates, so it’s time you patch your Windows systems. I’ll summarize some Patch Day highlights below, but you should visit Microsoft’s December Patch Day Summary page for more details

By the Numbers:

On Tuesday, Microsoft released seven security bulletins, fixing a total of 25 security vulnerabilities in many of their products. The affected products include:

all current versions of Windows,
Internet Explorer (IE),
Office,
and Exchange Server.

They rate three bulletins as Critical, four as Important.

Patch Day Highlights:

The Exchange update is the most interesting one, but lets start with what you should patch first. I’d start with the Internet Explorer (IE) update, as it closes a bunch of holes bad guys can use for drive-by download attacks. Next, even though Microsoft doesn’t rate it as Critical, the Exchange update fixes a few flaws attackers could leverage to access your users’ email (if they can get those users to click links). Since email is so important, I’d take care of that next. Then move on to the various Office updates, to make sure your users aren’t affected by malicious Office documents. Finally, even though it poses minimal risk, finish with the Graphics component update.

Quick Bulletin Summary:

We summarize December’s 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.

MS14-080 – Critical – Cumulative Internet Explorer update fixes 14 vulnerabilities – The Internet Explorer (IE) update primarily fixes a bunch of memory corruption flaws remote attackers could leverage to execute code. These are the types of flaws typically used in drive-by download attacks. If an attacker can get you to visit a site with malicious code, he could exploit these flaws to run code on your machine. If you have local administrator privileges, the attacker gains full control of your PC.
MS14-075 – Important– Four Exchange Server Vulnerabilities – Microsoft’s email server, Exchange, suffers from four security flaws. The worst are a pair of cross-site scripting (XSS) flaws. If an attacker can trick you into clicking a specially crafted link on a system you use for OWA, he could exploit these flaws to gain access to your email as you. The remaining flaws allow attackers to spoof emails to appear to come from someone else, or to spoof links that appear to link to somewhere else.
MS14-081 – Critical – Two Word Remote Code Execution Flaws – Word suffers from two flaws involving how it handles specially crafted Office files. In short, if an attacker can get you to open a malicious Office file, she can exploit these flaws to execute code on your computer.
MS14-082 – Important – Office Code Execution Flaw – Word, an Office component, suffers from yet another code execution vulnerability, similar to the two described above. I’m not sure why Microsoft included this is a separate bulletin, with a lower severity, since it seems to have a similar impact and mitigating factors as the flaws above.
MS14-083 – Important – Two Excel Code Execution Flaws – Excel suffers from a pair of code execution vulnerabilities attackers could exploit by getting you to interact with malicious spreadsheets.
MS14-084 – Important – Windows VBScript Memory Corruption Flaw – The Windows VBScript component suffers from a memory corruption flaw that attackers could leverage through your browser. If an attacker can lure you to a website with malicious code, he could exploit this flaw to execute code with your privileges.
MS14-085 – Important – Windows Graphic Component Information Disclosure Flaw – The Graphics component of Windows suffers from a minor flaw that attackers could leverage to learn about the current memory state of your computer. This flaw serves little purpose alone, but could help attackers exploit other memory corruption vulnerabilities easier.

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, and leave the moderate ones for last.

You can get the updates three ways:

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.
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.
Download December’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:

WEB-CLIENT Microsoft Internet Explorer Memory Corruption Vulnerability (CVE-2014-8966)
WEB-CLIENT Microsoft Internet Explorer Memory Corruption Vulnerability (CVE-2014-6376)
WEB-CLIENT Microsoft Internet Explorer Memory Corruption Vulnerability (CVE-2014-6375)
WEB-CLIENT Microsoft Internet Explorer Memory Corruption Vulnerability (CVE-2014-6374)
WEB Microsoft Graphics Component Information Disclosure Vulnerability (CVE-2014-6355)
FILE Microsoft Word Remote Code Execution Vulnerability (CVE-2014-6357)
FILE Microsoft Excel Global Free Remote Code Execution Vulnerability (CVE-2014-6360)
WEB-CLIENT Microsoft Internet Explorer ASLR Bypass Vulnerability (CVE-2014-6368)
WEB-CLIENT Microsoft Internet Explorer Memory Corruption Vulnerability (CVE-2014-6369)
WEB-CLIENT Microsoft Internet Explorer Memory Corruption Vulnerability (CVE-2014-6373)
EXPLOIT Adobe Flash Player Memory Corruption (CVE-2014-0574)
WEB-CLIENT Microsoft Internet Explorer Memory Corruption Vulnerability (CVE-2014-6327)
WEB MIcrosoft Internet Explorer XSS Filter Bypass Vulnerability (CVE-2014-6328)
WEB-CLIENT Microsoft Internet Explorer Memory Corruption Vulnerability (CVE-2014-6329)
WEB-CLIENT Microsoft Internet Explorer Memory Corruption Vulnerability (CVE-2014-6330)
FILE Microsoft Excel Invalid Pointer Remote Code Execution Vulnerability (CVE-2014-6361)
WEB-CLIENT Microsoft VBScript Memory Corruption Vulnerability (CVE-2014-6363)
WEB-CLIENT Microsoft VBScript Memory Corruption Vulnerability (CVE-2014-6366)
FILE Adobe Flash Player opcode pushwith Memory Corruption Vulnerability (CVE-2014-0586)
FILE Adobe Flash Player opcode pushscope Memory Corruption Vulnerability (CVE-2014-0585)

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. — Corey Nachreiner, CISSP (@SecAdept)