Allan Liska

Patch Tuesday, Good Riddance 2020 Edition

Microsoft today issued its final batch of security updates for Windows PCs in 2020, ending the year with a relatively light patch load. Nine of the 58 security vulnerabilities addressed this month earned Microsoft’s most-dire “critical” label, meaning they can be abused by malware or miscreants to seize remote control over PCs without any help from users.

Mercifully, it does not appear that any of the flaws fixed this month are being actively exploited, nor have any them been detailed publicly prior to today.

The critical bits reside in updates for Microsoft Exchange Server, Sharepoint Server, and Windows 10 and Server 2016 systems. Additionally, Microsoft released an advisory on how to minimize the risk from a DNS spoofing weakness in Windows Server 2008 through 2019.

Some of the sub-critical “important” flaws addressed this month also probably deserve prompt patching in enterprise environments, including a trio of updates tackling security issues with Microsoft Office.

“Given the speed with which attackers often weaponize Microsoft Office vulnerabilities, these should be prioritized in patching,” said Allan Liska, senior security architect at Recorded Future. “The vulnerabilities, if exploited, would allow an attacker to execute arbitrary code on a victim’s machine. These vulnerabilities affect Microsoft Excel 2013 through 2019, Microsoft 365 32 and 64 bit versions, Microsoft Office 2019 32 and 64 bit versions, and Microsoft Excel for Mac 2019.”

We also learned this week that Redmond quietly addressed a scary “zero-click” vulnerability in its Microsoft Teams platform that would have let anyone execute code of their choosing just by sending the target a specially-crafted chat message to a Teams users. The bug was cross-platform, meaning it could also have been used to deliver malicious code to people using Teams on non-Windows devices.

Researcher Oskars Vegeris said in a proof-of-concept post to Github that he reported the flaw to Microsoft at the end of August, but that Microsoft didn’t assign the bug a Common Vulnerabilities and Exposure (CVE) rating because it has a policy of not doing so for bugs that can be fixed from Microsoft’s end without user interaction.

According to Vegeris, Microsoft addressed the Teams flaw at the end of October. But he said the bug they fixed was the first of five zero or one-click remote code execution flaws he has found and reported in Teams. Reached via LinkedIn, Vegeris declined to say whether Microsoft has yet addressed the remaining Teams issues.

Separately, Adobe issued security updates for its Prelude, Experience Manager and Lightroom software. There were no security updates for Adobe Flash Player, which is fitting considering Adobe is sunsetting the program at the end of the year. Microsoft is taking steps to remove Flash from its Windows browsers, and Google and Firefox already block Flash by default.

It’s a good idea for Windows users to get in the habit of updating at least once a month, but for regular users (read: not enterprises) it’s usually safe to wait a few days until after the patches are released, so that Microsoft has time to iron out any chinks in the new armor.

But before you update, please make sure you have backed up your system and/or important files. It’s not uncommon for a Windows update package to hose one’s system or prevent it from booting properly, and some updates have been known to erase or corrupt files.

So do yourself a favor and backup before installing any patches. Windows 10 even has some built-in tools to help you do that, either on a per-file/folder basis or by making a complete and bootable copy of your hard drive all at once.

And if you wish to ensure Windows has been set to pause updating so you can back up your files and/or system before the operating system decides to reboot and install patches on its own schedule, see this guide.

As always, if you experience glitches or problems installing any of these patches this month, please consider leaving a comment about it below; there’s a better-than-even chance other readers have experienced the same and may chime in here with some helpful tips.

Microsoft Patch Tuesday, April 2020 Edition

Microsoft today released updates to fix 113 security vulnerabilities in its various Windows operating systems and related software. Those include at least three flaws that are actively being exploited, as well as two others which were publicly detailed prior to today, potentially giving attackers a head start in figuring out how to exploit the bugs.

Nineteen of the weaknesses fixed on this Patch Tuesday were assigned Microsoft’s most-dire “critical” rating, meaning malware or miscreants could exploit them to gain complete, remote control over vulnerable computers without any help from users.

Near the top of the heap is CVE-2020-1020, a remotely exploitable bug in the Adobe Font Manager library that was first detailed in late March when Microsoft said it had seen the flaw being used in active attacks.

The Adobe Font Manager library is the source of yet another zero-day flaw — CVE-2020-0938 — although experts at security vendor Tenable say there is currently no confirmation that the two are related to the same set of in-the-wild attacks. Both flaws could be exploited by getting a Windows users to open a booby-trapped document or viewing one in the Windows Preview Pane.

The other zero-day flaw (CVE-2020-1027) affects Windows 7 and Windows 10 systems, and earned a slightly less dire “important” rating from Microsoft because it’s an “elevation of privilege” bug that requires the attacker to be locally authenticated.

Many security news sites are reporting that Microsoft addressed a total of four zero-day flaws this month, but it appears the advisory for a critical Internet Explorer flaw (CVE-2020-0968) has been revised to indicate Microsoft has not yet received reports of it being used in active attacks. However, the advisory says this IE bug is likely to be exploited soon.

Researchers at security firm Recorded Future zeroed in on CVE-2020-0796, a critical vulnerability dubbed “SMBGhost” that was rumored to exist in last month’s Patch Tuesday but for which an out-of-band patch wasn’t released until March 12. The problem resides in a file-sharing component of Windows, and could be exploited merely by sending the victim machine specially-crafted data packets. Proof-of-concept code showing how to exploit the bug was released April 1, but so far there are no indications this method has been incorporated into malware or active attacks.

Recorded Future’s Allan Liska notes that one reason these past few months have seen so many patches from Microsoft is the company recently hired “SandboxEscaper,” a nickname used by the security researcher responsible for releasing more than a half-dozen zero-day flaws against Microsoft products last year.

“SandboxEscaper has made several contributions to this month’s Patch Tuesday,” Liska said. “This is great news for Microsoft and the security community at large.”

Once again, Adobe has blessed us with a respite from updating its Flash Player program with security fixes. I look forward to the end of this year, when the company has promised to sunset this buggy and insecure program once and for all. Adobe did release security updates for its ColdFusion, After Effects and Digital Editions software.

Speaking of buggy software platforms, Oracle has released a quarterly patch update to fix more than 400 security flaws across multiple products, including its Java SE program. If you’ve got Java installed and you need/want to keep it installed, please make sure it’s up-to-date.

Now for my obligatory disclaimers. Just a friendly reminder that while many of the vulnerabilities fixed in today’s Microsoft patch batch affect Windows 7 operating systems — including all three of the zero-day flaws — this OS is no longer being supported with security updates (unless you’re an enterprise taking advantage of Microsoft’s paid extended security updates program, which is available to Windows 7 Professional and Windows 7 enterprise users).

If you rely on Windows 7 for day-to-day use, it’s to think about upgrading to something newer. That something might be a computer with Windows 10. Or maybe you have always wanted that shiny MacOS computer.

If cost is a primary motivator and the user you have in mind doesn’t do much with the system other than browsing the Web, perhaps a Chromebook or an older machine with a recent version of Linux is the answer (Ubuntu may be easiest for non-Linux natives). Whichever system you choose, it’s important to pick one that fits the owner’s needs and provides security updates on an ongoing basis.

Keep in mind that while staying up-to-date on Windows patches is a must, it’s important to make sure you’re updating only after you’ve backed up your important data and files. A reliable backup means you’re not losing your mind when the odd buggy patch causes problems booting the system.

So do yourself a favor and backup your files before installing any patches. Windows 10 even has some built-in tools to help you do that, either on a per-file/folder basis or by making a complete and bootable copy of your hard drive all at once.

As always, if you experience glitches or problems installing any of these patches this month, please consider leaving a comment about it below; there’s a better-than-even chance other readers have experienced the same and may chime in here with some helpful tips. Also, keep an eye on the AskWoody blog from Woody Leonhard, who keeps a close eye on buggy Microsoft updates each month.

Further reading:

Qualys breakdown on April 2020 Patch Tuesday

SANS Internet Storm Center on Patch Tuesday