Tag Archives: Rollup

Security Update Exchange 2010-2019 (Mar2021)

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Update 16Mar2021: Added One-Click tool reference.

Another month, another set of security updates for Exchange Server 2016 and 2019, including out-of-band updates for Exchange 2013 CU23 and Exchange 2010 SP3 (Rollup 32). Given the risk of this vulnerability, security updates for older out-of-support CUs (Ex2016 CU8 was released December 2017) were also made available. According to the related Exchange team blog, these exploits are seen being used as part of an attack chain. After publication of this vulnerability named Hafnium, proof of concept kits were published after which variations started to appear (e.g. DearCry). Needless to say, the security update is critical and deployment should not be postponed – intermediate mitigations (with consequences) are also available.

These fixes address the following Remote Code Execution vulnerabilities:

The exploit can be fixed by security update, or in case of Exchange 2010 SP3 by applying a Rollup, which you can find in the table below per current Exchange version. Microsoft published security updates for older CUs as well on March 8th; these have been added to the table below.

Exchange BuildDownloadBuildArticleSupersedes
Exchange 2019 CU8Download15.2.792.10KB5000871KB4602269
Exchange 2019 CU7Download15.2.721.13KB5000871KB4602269
Exchange 2016 CU19Download15.1.2176.9KB5000871KB4602269
Exchange 2016 CU18Download15.1.2106.13KB5000871KB4602269
Exchange 2013 CU23Download15.0.1497.12KB5000871KB4593466
Exchange 2010 SP3 RU32Download14.3.513.0KB5000978
Exchange 2019 CU6Download15.2.659.12KB5000871
Exchange 2019 CU5Download15.2.595.8KB5000871
Exchange 2019 CU4Download15.2.529.13KB5000871
Exchange 2019 CU3Download15.2.464.15KB5000871
Exchange 2019 CU2Download15.2.397.11KB5000871
Exchange 2019 CU1Download15.2.330.11KB5000871
Exchange 2019 RTMDownload15.2.221.18KB5000871
Exchange 2016 CU17Download15.1.2044.13KB5000871
Exchange 2016 CU16Download15.1.1979.8KB5000871
Exchange 2016 CU15Download15.1.1913.12KB5000871
Exchange 2016 CU14Download15.1.1847.12KB5000871
Exchange 2016 CU13Download15.1.1779.8KB5000871
Exchange 2016 CU12Download15.1.1713.10KB5000871
Exchange 2016 CU11Download15.1.1591.18KB5000871
Exchange 2016 CU10Download15.1.1531.12KB5000871
Exchange 2016 CU9Download15.1.1466.16KB5000871
Exchange 2016 CU8Download15.1.1415.10KB5000871
Exchange 2013 CU22Download15.0.1473.6KB5000871
Exchange 2013 CU21Download15.0.1395.12KB5000871

Notes:

  • You may not be prompted for a reboot, but one is required.
  • When manually installing the update use an elevated command prompt, don’t just double-click the .msp. To apply an .msp from an elevated prompt, e.g. msiexec.exe /p <Full Path to File>.
  • When you need to update to a more current Cumulative Update first, update using an elevated command prompt, e.g. setup.exe /m:upgrade /IAcceptExchangeServerLicenseTerms
  • Per product group feedback, Exchange 2010 is not vulnerable to the same attack chain as Exchange 2013/2016/2019, hence the Rollup mentioning a single CVE.
  • When running product levels earlier than the ones patched, i.e. Exchange 2016 CU17, you are at risk. There are no patches for earlier product levels, so you need to update to a recent CU after which you can install the security update.
  • When installing a recent CU first in order to be able to install the security update, reboot after installing the CU, then install the security update. This prevents issues caused by files being locked or updating files pending replacement during reboot.
  • When you are significantly behind regarding keeping your Exchange servers up to date, the blog Upgrade Paths for CU’s and .NET might help in determining an update strategy.
  • The statement to stay up to date with at most CU n-1 is not some random adage; apart from features and fixes, it also allows you to quickly respond to these type of emergencies.
  • Make sure you have configured proper Anti-Virus/Malware exclusions for Exchange server, as documented here for Exchange 2016/2019. I’ve seen significant delays or even hangs during setup of Cumulative Updates because of paths and processes not being excluded. When running Exchange virtually, any I/O inspection running on top of your hypervisor is also considered anti-virus/malware software, such as Trend Micro Deep Inspection on VMWare.
  • When deploying CU(n) on top of CU(n-1) when an interim update already has been installed, it is recommended to uninstall the IU prior to deploying CU(n). While it might go through, an abort is likely with mention of detecting an IU (INTERIMUPDATEDETECTED) in Exchange Setup log.
  • Security Updates are Cumulative Update level specific. You cannot apply the update for Exchange 2016 CU18 to Exchange 2016 CU19. Note that the security update file has the same name for different Cumulative Updates; I would suggest tagging the file name with the CU level, e.g. Exchange2016-CU18-KB5000871-x64-en.msp.
  • The publication of security updates for some older CUs does not remove the necessity to update and patch with current CUs.

Indicators & Action
You may want to look for signs that your Exchange server might have been compromised (Indicators of Compromise or IOC). The article HAFNIUM targeting Exchange Servers with 0-day exploits explains this process. A tool is available to assist in scanning systems for indicators, the Microsoft Support Emergency Response Tool (MSERT).

There is also official communication to support this update, including steps to remediate issues with updates and steps to perform analysis (many people overlook the recommendation to run the update elevated for some reason). This deck can be found here: March 2021 Exchange Server Security Update – v1.2.65 – EN.pdf (thanks Chris Lehr).

Mitigations
I would also recommend the official follow-up post, which not only has been updated since the original post, but also includes mitigations for organizations which cannot deploy the update yet:

  • A script to configure IIS rewrite rules to block cookies used in the attack (mitigates CVE-2021-26855).
  • Disabling UM Services (mitigates CVE-2021-26857).
  • Disabling ECP application pool (mitigates CVE-2021-27065).
  • Disabling OAB application pool (addresses CVE-2021-26858).

Needless to say, steps like disabling ECP or OAB impacts client functionality.

MS published a One-Click Microsoft Exchange On-Premises Mitigation Tool for simplified one-click implementation of mitigation measures on Exchange 2013-2019.

Finally
Since some people are discovering artifacts of HAFNIUM dating before Microsoft’s official communication, people have been wondering how long this has been going on. For those interested, Krebson Security has published an article with a concise timeline of the events related to this attack.

Security Updates Exchange 2010-2019

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A quick blog that rather silently, Microsoft published hotfixes for a number of products few days ago, including Exchange Server 2010 up to Exchange Server 2019. These fixes address the following vulnerabilities:

  • CVE-2019-1084: Microsoft Exchange Information Disclosure Vulnerability, allowing non-printable characters to be added to Display Names.
  • CVE-2019-1136: Microsoft Exchange Server Elevation of Privilege Vulnerability, allowing NTLM MITM elevation permissions or impersonation through Exchange Web Services. This sounds like a variation on the NTLM MITM exploit which was fixed earlier this year with the February update cycle.
  • CVE-2019-1137: Microsoft Exchange Server Spoofing Vulnerability, allowing for cross-site scripting (XSS).

The CVE documents contain more details on the vulnerabilities. These exploits can be fixed by single security updates; you can download them here:

VersionCVE
2019
1084		CVE
2019
1136		CVE
2019
1137		DownloadBuildKB
2019 CU2XXLink15.2.397.54509408
2019 CU1XXLink15.2.330.94509408
2016 CU13XXXLink15.1.1779.44509409
2016 CU12XXXLink15.1.1713.84509409
2013 CU23XXXLink15.0.1497.34509409
2010 SP3 RU29XXLink14.3.468.04509410

Be advised that the Security Updates for Exchange 2013-2019 are Cumulative Update level specific. Unfortunately, the security update carries the same name for different CU’s, and you cannot apply the update for Exchange 2016 CU12 to Exchange 2016 CU11. I would suggest tagging the Cumulative Update in the file name when you store it, e.g. Exchange2016-KB4503027-x64-en_CU11.msp.

As with any patch or update, I’d recommend to apply this in a acceptance environment first, prior to implementing it in production.

Security Updates for Spoofing Vulnerability

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Ex2013 LogoUpdated April 12th: Notice on KB4487563

Today, as part of patch Tuesday, supported Exchange versions received security updates to remediate the following issues:

Security updates are available for the following product levels, and fix the vulnerability mentioned:

Build KB Download CVE-2019-0817 CVE-2019-0858
Exchange 2019 CU1 15.2.330.7 KB4487563 Download Yes Yes
Exchange 2019 15.2.221.16 KB4487563 Download Yes Yes
Exchange 2016 CU12 15.1.1713.6 KB4487563 Download Yes Yes
Exchange 2016 CU11 15.1.1591.16 KB487563 Download Yes Yes
Exchange 2013 CU22 15.0.1473.4 KB487563 Download Yes Yes
Exchange 2010 SP3 RU27 14.3.452.0 KB4491413 Download Yes No

Notes:

  • CVS-2019-0858 does not apply to Exchange 2010.
  • Exchange 2010 is currently in Extended Support. Extended support for Exchange 2010 ends January 14, 2020.
  • Don’t forget to put the Exchange server in maintenance mode prior to updating.
  • If you want to speed up the update process for systems without internet access, you can follow the procedure described here to disable publisher’s certificate revocation checking.
  • The order of installation shouldn’t matter with the “every server is an island” concept, yet recommended is to upgrade internet-facing first, followed by non-internet-facing servers, and finally Edge Transports.

Notice on KB4487563:
Apart from the known issues mentioned in KB4487563, there are reports the fix terminates while stopping services, and the following error is being logged:
[Error] System.Management.Automation.CommandNotFoundException: The term ‘Stop-SetupService’ is not recognized as the name of a cmdlet, function, script file, or operable program.

This Stop-SetupService isn’t a regular cmdlet, and I assume is an alias created by the update. However, there are reports this operation fails. In those circumstances, next to retrying installation of the update, a workaround might be opening up a PowerShell session and adding the alias yourself using New-Alias Stop-SetupService Stop-Service, followed by running the update. The alias isn’t persistent, so will be gone after you close your session.

Caution:
As for any update, I recommend to thoroughly test updates in a test environment prior to implementing them in production. When you lack such facilities, hold out a few days and monitor the comments on the original publication or forums for any issues.

Exchange Updates – February 2019

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Update: Added note that Exchange 2010 SP3 RU26 adds support for Windows Server 2012 R2.

Today, the Exchange Team released the overdue quarterly Cumulative Updates for Exchange Server 2013, Exchange 2016 and Exchange 2019, as well as a Rollup for Exchange Server 2010.

The KB articles that describe the fixes in each release and product downloads are available as follows:

Version Build KB Download UMLP Schema
Exchange 2019 CU1 15.2.330.5 KB4471391 VLSC N
Exchange 2016 CU12 15.1.1713.5 KB4471392 Download UMLP N
Exchange 2013 CU22 15.0.1473.3 KB4345836 Download UMLP N
Exchange 2010 SP3 RU26 14.3.442.0 KB4487052 Download N

This update contain the following important changes and notes:

  • Due to issue CVE-2018-8581, the EWS architecture was changed, in particular push notifications. Details on the change are described in KB4490060; while the change has been tested against EWS clients such as Outlook for Mac and Skype for Business, organizations may need to test any applications leveraging EWS to estimate potential impact of installing these Cumulative Updates or Rollup. In addition, organizations are advised to password reset Exchange computer accounts.
  • These Exchange builds introduces a change in the shared permissions model (this does not apply to Split Permissions Model). Result is that Exchange no longer requires fargoing permissions in Active Directory (e.g. WriteDACL on root of domain). To makes these changes become effective:
    • For Exchange 2013-2019 Cumulative Updates, run setup using /PrepareAD. In multi-forest environments, this needs to be done in every domain of the forest.
    • For Exchange 2010, go through the instructions mentioned in KB4490059.
  • Organizations considering moving to the Split Permissions because of CVE-2018-8581 should know Microsoft fully supports both models. Switching can have serious consequences and therefor should be fully evaluated.
  • This build of Exchange 2019 introduces cmdlets to block usage of legacy authentication protocols for users through policies, e.g. Basic Authentication.
  • Prior to deploying Exchange 2016 CU12 or Exchange 2013 CU22 on Edge Transport servers, install Visual C++ 2012 Runtime.
  • These Cumulative Updates will remove the DisableLoopbackCheck key when present; removing this key was a mitigation for CVE-2018-8581.
  • Exchange 2010 SP3 RU26 adds support for Windows Server 2012 R2, to accommodate for the Hybrid Agent.

Exchange 2019 CU1 fixes:

  • 4487596 Emails are blocked in moderator mailbox Outbox folder when you send large volumes of emails in Exchange Server 2019
  • 4487591 The recipient scope setting doesn’t work for sibling domains when including OUs in the scope in Exchange Server 2019
  • 4487602 Outlook for Mac users can still expand a distribution group when hideDLMembership is set to true in Exchange Server 2019
  • 4488076 Outlook on the Web can’t be loaded when users use an invalid Windows language in operating system in Exchange Server 2019
  • 4488079 Exchange Server 2016 allows adding Exchange Server 2019 mailbox server into a same DAG and vice versa
  • 4488263 X-MS-Exchange-Organization-BCC header isn’t encoded correctly in Exchange Server 2019
  • 4488080 New-MigrationBatch doesn’t honor RBAC management scope in Exchange Server 2019
  • 4488262 Delivery Reports exception when tracking a meeting request that’s sent with a room resource in Exchange Server 2019
  • 4488268 Disable the irrelevant Query logs that’re created in Exchange Server 2019
  • 4488267 Test-OAuthConnectivity always fails when Exchange Server uses proxy to connect to Internet in Exchange Server 2019
  • 4488266 Client application doesn’t honor EwsAllowList in Exchange Server 2019
  • 4488265 “There are problems with the signature” error occurs for digital signature message if attachment filtering is enabled in Exchange Server 2019
  • 4488398 “The Microsoft Exchange Replication service may not be running on server” error when you add a mailbox database copy in Exchange Server 2019
  • 4488264 Mailbox that has a bad move request can’t be cleaned up from destination mailbox database in Exchange Server 2019
  • 4488261 Event ID 1002 when the store worker process crashes in Exchange Server 2019
  • 4488260 New-MailboxExportRequest and New-MailboxImportRequest don’t honor RBAC management scope in Exchange Server 2019
  • 4488259 MailTip shows wrong number of users for a distribution group if the users are in different domains in Exchange Server 2019
  • 4488258 OAuth authentication is removed when saving MAPI virtual directory settings in EAC in Exchange Server 2019
  • 4490060 Exchange Web Services Push Notifications can be used to gain unauthorized access
  • 4490059 Reducing permissions required to run Exchange Server using Shared Permissions Model

Exchange 2016 CU12 fixes:

  • 4487596 Emails are blocked in moderator mailbox Outbox folder when you send large volumes of emails in Exchange Server 2016
  • 4456241 You receive a meeting request that has a “not supported calendar message.ics” attachment in Exchange Server 2016
  • 4456239 New-MailboxRepairRequest doesn’t honor RBAC RecipientWriteScope restrictions in Exchange Server 2016
  • 4487591 The recipient scope setting doesn’t work for sibling domains when including OUs in the scope in Exchange Server 2016
  • 4468363 MRM does not work for mailboxes that have an online archive mailbox in Exchange Server
  • 4487603 “The action cannot be completed” error when you select many recipients in the Address Book of Outlook in Exchange Server 2016
  • 4487602 Outlook for Mac users can still expand a distribution group when hideDLMembership is set to true in Exchange Server 2016
  • 4488076 Outlook on the Web can’t be loaded when users use an invalid Windows language in operating system in Exchange Server 2016
  • 4488079 Exchange Server 2016 allows adding Exchange Server 2019 mailbox server into a same DAG and vice versa
  • 4488077 Can’t configure voice mail options when user is in different domain in Exchange Server 2016
  • 4488263 X-MS-Exchange-Organization-BCC header isn’t encoded correctly in Exchange Server 2016
  • 4488080 New-MigrationBatch doesn’t honor RBAC management scope in Exchange Server 2016
  • 4488262 Delivery Reports exception when tracking a meeting request that’s sent with a room resource in Exchange Server 2016
  • 4488268 Disable the irrelevant Query logs that’re created in Exchange Server 2016
  • 4488267 Test-OAuthConnectivity always fails when Exchange Server uses proxy to connect to Internet in Exchange Server 2016
  • 4488266 Client application doesn’t honor EwsAllowList in Exchange Server 2016
  • 4488265 “There are problems with the signature” error occurs for digital signature message if attachment filtering is enabled in Exchange Server 2016
  • 4488264 Mailbox that has a bad move request can’t be cleaned up from destination mailbox database in Exchange Server 2016
  • 4488261 Event ID 1002 when the store worker process crashes in Exchange Server 2016
  • 4488260 New-MailboxExportRequest and New-MailboxImportRequest don’t honor RBAC management scope in Exchange Server 2016
  • 4488259 MailTip shows wrong number of users for a distribution group if the users are in different domains in Exchange Server 2016
  • 4488258 OAuth authentication is removed when saving MAPI virtual directory settings in EAC in Exchange Server 2016
  • 4490060 Exchange Web Services Push Notifications can be used to gain unauthorized access
  • 4490059 Reducing permissions required to run Exchange Server using Shared Permissions Model

Exchange 2013 CU22 fixes:

  • 4487603 “The action cannot be completed” error when you select many recipients in the Address Book of Outlook in Exchange Server 2013
  • 4490060 Exchange Web Services Push Notifications can be used to gain unauthorized access
  • 4490059 Reducing permissions required to run Exchange Server using Shared Permissions Model

Exchange 2010 SP3 RU26 fixes:

  • 4490060 Exchange Web Services Push Notifications can be used to gain unauthorized access

Notes:

  • These Cumulative Updates do not contain schema changes compared to their previous Cumulative Update. However, due to changes in the permissions architecture, you need to run setup /PrepareAD to implement these changes as well as apply any RBAC changes, before deploying or updating Exchange servers.
  • When upgrading from an n-2 or earlier version of Exchange, or an early version of the .NET Framework, consult Upgrade Paths for CU’s & .NET.
  • Don’t forget to put the Exchange server in maintenance mode prior to updating. Regardless, setup will put the server in server-wide offline mode post-analysis, before making actual changes.
  • When using Exchange hybrid deployments or Exchange Online Archiving (EOA), you are required to delay installing at most one version (n-1).
  • If you want to speed up the update process for systems without internet access, you can follow the procedure described here to disable publisher’s certificate revocation checking.
  • Cumulative Updates can be installed directly; no need to install RTM prior to installing Cumulative Updates.
  • Once installed, you can’t uninstall a Cumulative Update nor any of the installed Exchange server roles.
  • The order of installation shouldn’t matter with the “every server is an island” concept, yet recommended is to upgrade internet-facing, non-internet-facing servers first, followed by Edge Transports.

Caution:

As for any update, I recommend to thoroughly test updates in a test environment prior to implementing them in production. When you lack such facilities, hold out a few days and monitor the comments on the original publication or forums for any issues.

Security Updates for Exchange 2016, 2013 and 2010

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Ex2013 LogoA quick heads-up as during my vacation Microsoft released security updates for supported releases of Exchange Server 2016 and 2013 as well as Exchange Server 2010.

The security updates patch issues as reported in the following Microsoft Common Vulnerabilities and Exposures:

  • CVE-2018-8302 Microsoft Exchange Memory Corruption Vulnerability
  • CVE-2018-8374 Microsoft Exchange Server Tampering Vulnerability (Exchange 2016 only)

You can download the security updates here:

Notes:

  • Be advised that Exchange 2010 SP3 Rollup 23, like recent Cumulative Updates of Exchange 2016 and 2013, requires Visual C++ Redistributable Packages for Visual Studio 2013 (download).
  • KB4340731 supersedes the previous security update KB4092041 for Exchange 2016 and Exchange 2013.

Be advised that for Exchange 2013 and 2016, Security Updates are Cumulative Update level specific. While the downloaded security updates may carry the same name, the files are different and you cannot apply the downloaded security update file for Exchange 2016 CU8 to Exchange 2016 CU9. I suggest adding some form of identification of the Cumulative Update to the file name when you archive it, e.g. Exchange2016-KB4340731-x64-en-CU10.msp.

As with any patch or update, I’d recommend to thoroughly test this in a test and acceptance environment first, prior to implementing it in production.