CVE-2020-0796

Microsoft Patch Tuesday, June 2020 Edition

Microsoft today released software patches to plug at least 129 security holes in its Windows operating systems and supported software, by some accounts a record number of fixes in one go for the software giant. None of the bugs addressed this month are known to have been exploited or detailed prior to today, but there are a few vulnerabilities that deserve special attention — particularly for enterprises and employees working remotely.

June marks the fourth month in a row that Microsoft has issued fixes to address more than 100 security flaws in its products. Eleven of the updates address problems Microsoft deems “critical,” meaning they could be exploited by malware or malcontents to seize complete, remote control over vulnerable systems without any help from users.

A chief concern among the panoply of patches is a trio of vulnerabilities in the Windows file-sharing technology (a.k.a. Microsoft Server Message Block or “SMB” service). Perhaps most troubling of these (CVE-2020-1301) is a remote code execution bug in SMB capabilities built into Windows 7 and Windows 2008 systems — both operating systems that Microsoft stopped supporting with security updates in January 2020. One mitigating factor with this flaw is that an attacker would need to be already authenticated on the network to exploit it, according to security experts at Tenable.

The SMB fixes follow closely on news that proof-of-concept code was published this week that would allow anyone to exploit a critical SMB flaw Microsoft patched for Windows 10 systems in March (CVE-2020-0796). Unlike this month’s critical SMB bugs, CVE-2020-0796 does not require the attacker to be authenticated to the target’s network. And with countless company employees now working remotely, Windows 10 users who have not yet applied updates from March or later could be dangerously exposed right now.

Microsoft Office and Excel get several updates this month. Two different flaws in Excel (CVE-2020-1225 and CVE-2020-1226) could be used to remotely commandeer a computer running Office just by getting a user to open a booby-trapped document. Another weakness (CVE-2020-1229) in most versions of Office may be exploited to bypass security features in Office simply by previewing a malicious document in the preview pane. This flaw also impacts Office for Mac, although updates are not yet available for that platform.

After months of giving us a welcome break from patching, Adobe has issued an update for its Flash Player program that fixes a single, albeit critical security problem. Adobe says it is not aware of any active exploits against the Flash flaw. Mercifully, Chrome and Firefox both now disable Flash by default, and Chrome and IE/Edge auto-update the program when new security updates are available. Adobe is slated to retire Flash Player later this year. Adobe also released security updates for its Experience Manager and Framemaker products.

Windows 7 users should be aware by now that while a fair number of flaws addressed this month by Microsoft affect Windows 7 systems, this operating system 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).

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 a wonky Windows update 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.

Further reading:

AskWoody and Martin Brinkmann on Patch Tuesday fixes and potential pitfalls

Trend Micro’s Zero Day Initiative June 2020 patch lowdown

U.S-CERT on Active Exploitation of CVE-2020-0796

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