Recorded Future

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, Sept. 2020 Edition

Microsoft today released updates to remedy nearly 130 security vulnerabilities in its Windows operating system and supported software. None of the flaws are known to be currently under active exploitation, but 23 of them could be exploited by malware or malcontents to seize complete control of Windows computers with little or no help from users.

The majority of the most dangerous or “critical” bugs deal with issues in Microsoft’s various Windows operating systems and its web browsers, Internet Explorer and Edge. September marks the seventh month in a row Microsoft has shipped fixes for more than 100 flaws in its products, and the fourth month in a row that it fixed more than 120.

Among the chief concerns for enterprises this month is CVE-2020-16875, which involves a critical flaw in the email software Microsoft Exchange Server 2016 and 2019. An attacker could leverage the Exchange bug to run code of his choosing just by sending a booby-trapped email to a vulnerable Exchange server.

“That doesn’t quite make it wormable, but it’s about the worst-case scenario for Exchange servers,” said Dustin Childs, of Trend Micro’s Zero Day Initiative. “We have seen the previously patched Exchange bug CVE-2020-0688 used in the wild, and that requires authentication. We’ll likely see this one in the wild soon. This should be your top priority.”

Also not great for companies to have around is CVE-2020-1210, which is a remote code execution flaw in supported versions of Microsoft Sharepoint document management software that bad guys could attack by uploading a file to a vulnerable Sharepoint site. Security firm Tenable notes that this bug is reminiscent of CVE-2019-0604, another Sharepoint problem that’s been exploited for cybercriminal gains since April 2019.

Microsoft fixed at least five other serious bugs in Sharepoint versions 2010 through 2019 that also could be used to compromise systems running this software. And because ransomware purveyors have a history of seizing upon Sharepoint flaws to wreak havoc inside enterprises, companies should definitely prioritize deployment of these fixes, says Alan Liska, senior security architect at Recorded Future.

Todd Schell at Ivanti reminds us that Patch Tuesday isn’t just about Windows updates: Google has shipped a critical update for its Chrome browser that resolves at least five security flaws that are rated high severity. If you use Chrome and notice an icon featuring a small upward-facing arrow inside of a circle to the right of the address bar, it’s time to update. Completely closing out Chrome and restarting it should apply the pending updates.

Once again, there are no security updates available today for Adobe’s Flash Player, although the company did ship a non-security software update for the browser plugin. The last time Flash got a security update was June 2020, which may suggest researchers and/or attackers have stopped looking for flaws in it. Adobe says it will retire the plugin at the end of this year, and Microsoft has said it plans to completely remove the program from all Microsoft browsers via Windows Update by then.

Before you update with this month’s patch batch, please make sure you have backed up your system and/or important files. It’s not uncommon for Windows updates to hose one’s system or prevent it from booting properly, and some updates even have 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.