Newsletter Archives

• A March security patch, for CVE-2020-0796, gets a publicly available proof of concept

  Posted on June 5, 2020 at 13:42 CDT by woody • Comment in the Forums

  If you haven’t yet installed the March or April or May security patches, time to get cookin’.

  Ionut Ilascu at Bleeping Computer just reported on a publicly available exploit for the SMB security hole.

  Working exploit code that achieves remote code execution on Windows 10 machines is now publicly available for CVE-2020-0796, a critical vulnerability in Microsoft Server Message Block (SMB 3.1.1)… Known by various names (SMBGhost, CoronaBlue, NexternalBlue, BluesDay), the security flaw can be leveraged by an unauthenticated attacker to spread malware from one vulnerable system to another without user interaction.

  I don’t see anything out in the wild yet, but it’s only a matter of time.

  Yes, you do need to patch sooner or later.

  Windows Patches/Security CVE-2020-0796, March 2020 Black Tuesday

• Widespread reports of problems with the second March Win10 cumulative update, KB 4551762, the SMBv3 patch

  Posted on March 14, 2020 at 08:38 CDT by woody • Comment in the Forums

  I was afraid this would happen. When Microsoft releases two security patches back-to-back, it’s rare that the second patch goes in without problems.

  I’m seeing lots of reports with problems with Thursday’s post-Patch-Tuesday cumulative update, KB 4551762.

  Günter Born kicked off the discussion on Borncity with Windows 10: KB4551762 causes errors 0x800f0988 and 0x800f0900.

  Mayank Parmar at Windows Latest has more complaint reports — and they’re extensive:

  • The aforementioned errors on installation
  • Random reboots
  • Performance hits (which are always hard to verify)

  People who already have installation issues will be lucky enough to have Windows to automatically repair the patch is manually removed. Alternatively, some will have to undergo the recovery process and reinstall their Windows 10 copy if the PC remains slow and buggy.

  We’re also getting lots of reports about the new cumulative update zapping user profiles, just like the original Patch Tuesday patch and last month’s cumulative update.

  There are no in-the-wild exploits of the SMBv3 security hole, although there are many Proof of Concept demos. Kevin Beaumont has tried and failed to crack it in a meaningful way. We’ve had a couple of anonymous posts that point to other potential problems, but I haven’t seen any of them in the real world.

  Finally, @Alex5723 notes that MS has changed the Knowledge Base article associated with the patch, with a worthwhile inclusion:

  SMB Compression is not yet used by Windows or Windows Server, and disabling SMB Compression has no negative performance impact.

  Microsoft also inserted a clarification (for Dummies like me!) explaining why the Server Core versions are the ones affected.

  ‘Softie Nate Warfield tweeted:

  Full Server is not released as part of the Windows Semi-Annual Channel releases; only Server Core.

  As such, Full Server is not affected, only the listed Server Core editions.

  Which is what numerous people told me here on the forum. Thanks, all!

  We’re still at MS-DEFCON 2.

  Windows Patches/Security CVE-2020-0796, KB 4551762, March 2020 Black Tuesday

• CVE-2020-0796, the SMBv3 security hole, doesn’t pose an immediate threat

  Posted on March 13, 2020 at 16:52 CDT by woody • Comment in the Forums

  I’ve been sitting on pins and needles wondering when an in-the-wild exploit for the just-patched SMBv3 security hole might appear.

  Looks like it’s much harder than many folks expected. Kevin Beaumont just posted this:

  

  We’re going to stay at MS-DEFCON 2 for the foreseeable future, particularly because we’re seeing many more reports of the disappearing icons/temporary profile bug.

  Windows Patches/Security CVE-2020-0796, KB 4551762, March 2020 Black Tuesday

• Heads up: Microsoft posts a fix for that SMBv3 security hole. Get ready to install this month’s Windows patches.

  Posted on March 12, 2020 at 10:57 CDT by woody • Comment in the Forums

  Microsoft just released the patch that it almost released on Tuesday. It’s the SMBv3 patch that’s set the security community on fire.

  KB 4551762, which fixes CVE-2020-0796 is a regular, old-fashioned Win10 cumulative update, but it’s only made for Win10 1903, 1909, Server  1903 Core and Server 1909 Core. (I still have no idea why only Server Core versions are affected.)

  Anyway, I’m going to keep my eyes open for any obvious problems and, if the coast looks reasonably clear, we may be moving to MS-DEFCON 3 or 4 pretty quickly.

  For now, hold off. There are no known exploits. But be ready to twitch that clicking finger.

  Will keep you posted.

  UPDATE: 24 hours later, I still haven’t seen an in-the-wild exploit. But there are many reports of a repeat of the “missing icon”/temporary profile bug associated with KB 4551762.

  Kevin Beaumont tweeted:

  For anybody pondering, I’ve tried various exploits for CVE-2020-0796 – with a default config and vulnerable Windows 10 install, Windows Defender detects the exploit attempt. If you have automatic updates enabled you will also have the patch already.

  It’s a significant security hole, but it doesn’t appear to be an imminent threat.

  Mayank Parmar has a recounting of the bugs in Windows Latest.

  Still watching.

  Windows Patches/Security CVE-2020-0796, KB 4551762, March 2020 Black Tuesday

• Patch Lady – we have an out of band on that SMBv3

  Posted on March 12, 2020 at 10:48 CDT by Susan Bradley • Comment in the Forums

  https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-0796

  https://support.microsoft.com/en-us/help/4551762/windows-10-update-kb4551762

   

  At this time I”m not seeing active attacks and NO ONE should be STUPID enough to have port 445 a SMB file sharing port open to the web.  So I’m still in don’t panic, don’t install and let’s test mode.

  Windows Security CVE-2020-0796, KB 4541762

• It looks like the announced-but-not-fixed CVE-2020-0796 “CoronaBlue” vuln is only for Server 1903 and 1909

  Posted on March 11, 2020 at 08:21 CDT by woody • Comment in the Forums

  I’ll have more details about this shortly, but many of you admins are rightly concerned about the CVE-2020-0796 security hole, which was announced, then not announced, then announced again in Microsoft ADV200005 | Microsoft Guidance for Disabling SMBv3 Compression.

  Long story short, it looks like MS was poised to release a patch yesterday, then decided at the last minute to cancel the patch — but somehow word of the cancellation didn’t make it to at least two organizations that published details about it.

  It looks like the security hole only affects Win10 1903, 1909, Server 1903 and 1909. Per Florian Roth:

  

  There’s a lot of information available about the hole and countermeasures from Satnam Narang on Tenable, from Sergiu Gatlan at BleepingComputer, Catalin Cimpanu at ZDNet and, in the past couple of hours, Dan Goodin at Ars Technica. Those of you running networks with SMBv3 should take a look.

  If you’re running a network on Win7 or Server 2008 R2, you’re good. SMBv3 didn’t even exist back then. 🙂

  And if you aren’t in charge of a network, sit back and smile. You have other things to worry about.

  UPDATE: Catalin Cimpanu now says:

  I have now seen/talked to 3 different people claiming they found the bug in less than 5 minutes. I won’t be surprised if exploits pop up online by the end of the day.

  Windows Patches/Security CVE-2020-0796, SMBv3