Security Updates Exchange 2013-2019 (May2022)

The Exchange PG released May updates for Exchange Server 2013, 2016 and 2019.

Note that per this cycle, Security Updates will be packaged in an executable wrapper. This should trigger the running elevated prompt, thus preventing any potential issues from simply double-clicking the .MSP file. More about the new package format, options for logging and command-line switches are mentioned in an article dedicated to the change of distribution method here.

The vulnerability addressed in the Security Updates for May is:

VulnerabilityCategorySeverityRating
CVE-2022-21978Elevation of PrivilegeImportantCVSS:3.1 8.2 / 7.1

The following Security Updates address this vulnerability:

ExchangeDownloadBuildKBSupersedes
Exchange 2019 CU12Download15.2.1118.9KB5014261
Exchange 2019 CU11Download15.2.986.26KB5014261
Exchange 2016 CU23Download15.1.2507.9KB5014261
Exchange 2016 CU22Download15.1.2375.28KB5014261
Exchange 2013 CU23Download15.0.1497.36KB5014260

The SU also fix the following issue:

  • KB5013118 Exchange Service Host service fails after installing March 2022 security update

Important: As mentioned in the announcement, you must run /PrepareAllDomains after deploying the SU because of hardening measures. Exception is when you have multiple domains and some of them are never prepped; in that case prepare the individual domains required. Using your currently deployed binaries, run the following command, where the /IAccept switch you need to use depends on the Exchange version deployed and whether you provide diagnostics information:

& $exbin\setup.exe /PrepareAllDomains /[IAcceptExchangeServerLicenseTerms|IAcceptExchangeServerLicenseTerms_DiagnosticDataON|IAcceptExchangeServerLicenseTerms_DiagnosticDataOFF]

Be advised that these security updates are Cumulative Update level specific. You cannot apply the update for Exchange 2019 CU12 to Exchange 2019 CU11. Also, the security update download has the same name for different Cumulative Updates, and I would suggest tagging the file name with the CU level, e.g. Exchange2019-CU10-KBXXXXXX-x64-en.msp.

Exchange servers running as part of hybrid deployment are running services, and thus need to be included in the patch cycle. If you are running Exchange 2019 CU12 Management Tools-only (for recipient management), you do not need to deploy this SU.

On a final note, as with any patch or update, I’d recommend to apply this in a test environment first, prior to implementing it in production. However, it is not recommended to wait for regular maintenance cycles when it concerns security updates, and follow a more agile approach; the ratings are an indication of the urgency.

Exchange Updates (and more) – H1 2022

20220423: Added TLS 1.3 note.

The Exchange Team released the quarterly half-yearly Cumulative Updates for Exchange Server 2019 and Exchange 2016. You read that right, half-yearly updates are replacing the cadence of quarterly update servicing model for Exchange Server. Effectively, this will be Exchange 2019 only, as Exchange 2016 will be out of mainstream support in H2 of 2022, and will therefor only receive Security Updates after this round. Note that this change also alters the effective ‘current’ state (n-1 or later) of your Exchange Server environment from half year to one year.

And that’s not the only good news that comes with these sets of updates. In short:

  • If you run Exchange 2019 in Hybrid only for the purpose of managing recipients, you can now use Exchange 2019 CU12’s Exchange Management Tools to accomplish this; no more need to have an Exchange server running just for this. More details here.
  • Exchange 2019 CU12 will reintroduce the Hybrid Key option. Its Hybrid Configuration Wizard supports this licensing method.
  • Exchange 2019 CU12 support managing the Hybrid Agent with MFA-enabled accounts.
  • Exchange 2019 CU12 adds support for Windows Server 2022, both for its underlying operating system, as well as deployment in environments running Windows Server 2022 Domain Controllers.
  • Note that while Windows Server 2022 supports TLS 1.3, Exchange 2019 CU12 on WS2022 does not yet support it. Adding support is scheduled for somewhere next year.
  • The supportability matrix has been updated for the supported Windows Server 2022 scenarios.
  • Exchange Server is now also part of Microsoft’s Bounty Program, which is an indication of continued focus for customers still running Exchange Servers on-premises.

Links to the updates as well as a description of changes and fixes are described below. The column Schema and AD indicate if the CU contains Schema (/PrepareSchema) and Active Directory (PrepareAD) changes compared to the previous CU. Refer to the Exchange Schema page for schema and related versioning information.

VersionBuildKBDownloadUMLPSchemaAD
Exchange 2019 CU1215.2.1118.7KB5011156Download NY
Exchange 2016 CU2315.1.2507.6KB5011155DownloadUMLPNY

Apart from DST changes and the fixes mentioned below, these Cumulative Updates also contain a change which will not allow using UNC paths with several cmdlets. More information about this change and cmdlets affected can be found here: KB5014278.

Exchange 2019 CU12 fixes:

  • 5012757 “Migration user… can’t be found” error when using Start-MigrationUser after batch migration fails
  • 5012758 Start-MailboxAssistant is not available in Exchange Server 2019
  • 5012760 You can’t access OWA or ECP after installing the July 2021 security update
  • 5012761 External attendees see “Send the Response Now” although no response was requested in Exchange Server
  • 5012762 PST creation is unexpectedly triggered again during multiple mailbox export
  • 5012765 Email stuck in queue starting from “2022/1/1 00:01:00 UTC+0” on all Exchange on-premises servers
  • 5012766 Transport Services fail repeatedly because of * Accepted Domain
  • 5012768 Start-MigrationUser and Stop-MigrationUser are unavailable for on-premises Exchange Server 2019 and 2016
  • 5012769 Invalid New Auth Certificate for servers that are not on UTC time zone
  • 5012770 No response from public folder for users migrating to Microsoft Exchange 2019
  • 5012772 Items are skipped at the start of a new search page request
  • 5012773 OWAMailboxPolicy is bypassed and high resolution profile images can be uploaded
  • 5012774 Can’t change default path for Trace log data in Exchange Server 2019 and 2016
  • 5012775 No additional global catalog column in the address book service logs
  • 5012776 Exchange Server 2019 help link in OWA redirects users to online help for Exchange Server 2016
  • 5012777 Can’t find forwarded messages that contain attachments in Exchange Server 2019
  • 5012778 Exchange Server stops responding when processing PDF files with set transport rule
  • 5012779 Invalid new auth certificate for servers that are not on UTC time zone
  • 5012780 Disable-Mailbox does not remove LegacyExchangeDN attribute from on-premises Exchange 2019
  • 5012781 Exchange Server 2019 and 2016 DLP doesn’t detect Chinese resident ID card numbers
  • 5012782 MS ExchangeDiagnostic Service causes errors during service startup and initialization in Microsoft Exchange 2019
  • 5012783 Can’t restore data of a mailbox when LegacyDN is empty in the database
  • 5012784 Exchange 2016 CU21 and Exchange 2019 CU10 cannot save “Custom Attributes” changes in EAC
  • 5012785 Read Only Domain Controllers (RODCs) in other domains do not get desired permissions
  • 5012786 Forwarded meeting appointments are blocked or considered spam
  • 5012787 Download domains created per CVE-2021-1730 don’t support ADFS authentication in OWA
  • 5012789 Can’t use Copy Search Results after eDiscovery & Hold search
  • 5012790 OWA doesn’t remove the “loading” image when a message is opened in Chrome and Edge browsers
  • 5012791 MailboxAuditLog doesn’t work in localized (non-English) environments

Exchange 2016 CU23 fixes:

  • 5012757 “Migration user… can’t be found” error when using Start-MigrationUser after batch migration fails
  • 5012760 You can’t access OWA or ECP after installing the July 2021 security update
  • 5012761 External attendees see “Send the Response Now” although no response was requested in Exchange Server
  • 5012765 Email stuck in queue starting from “2022/1/1 00:01:00 UTC+0” on all Exchange on-premises servers
  • 5012768 Start-MigrationUser and Stop-MigrationUser are unavailable for on-premises Exchange Server 2019 and 2016
  • 5012769 Invalid New Auth Certificate for servers that are not on UTC time zone
  • 5012774 Can’t change default path for Trace log data in Exchange Server 2019 and 2016
  • 5012779 Invalid new auth certificate for servers that are not on UTC time zone
  • 5012780 Disable-Mailbox does not remove LegacyExchangeDN attribute from on-premises Exchange 2019
  • 5012781 Exchange Server 2019 and 2016 DLP doesn’t detect Chinese resident ID card numbers
  • 5012782 MS ExchangeDiagnostic Service causes errors during service startup and initialization in Microsoft Exchange 2019
  • 5012783 Can’t restore data of a mailbox when LegacyDN is empty in the database
  • 5012784 Exchange 2016 CU21 and Exchange 2019 CU10 cannot save “Custom Attributes” changes in EAC
  • 5012786 Forwarded meeting appointments are blocked or considered spam
  • 5012787 Download domains created per CVE-2021-1730 don’t support ADFS authentication in OWA
  • 5012789 Can’t use Copy Search Results after eDiscovery & Hold search
  • 5012791 MailboxAuditLog doesn’t work in localized (non-English) environments
  • 5012829 Group metrics generation fails in multidomain environment

Notes:

  • If these Cumulative Updates contain schema changes compared to the Cumulative Update you currently have deployed, you need to run Setup with /PrepareSchema. If they contain Active Directory changes, you need to run /PrepareAD. Alternatively, permissions permitting, you can let Setup perform this step. Consult the Exchange schema versions page for schema and related versioning information.
  • 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), support requires you to trail 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 upgraded, you can’t uninstall a Cumulative Update nor any of the installed Exchange server roles.
  • The recommended upgrade order is 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 Exchange 2013-2019 (Mar2022)

The Exchange PG released March updates for Exchange Server 2013, 2016 and 2019. More detailed information on patching and how to get current when running an earlier CU of Exchange, can be found at the original blog post here.

The vulnerabilities addressed in these security updates are:

VulnerabilityCategorySeverityRating
CVE-2022-23277Remote Code ExecutionCriticalCVSS:3.1 8.8 / 7.7
CVE-2022-24463SpoofingImportantCVSS:3.1 6.5 / 5.7

These vulnerabilities are addressed in the following security updates below. The exception is KB5010324 which does not fix CVE-2022-24463 for Exchange 2013. If this is because of the severity classification or the problem being non-existent for Exchange 2013, has not been not disclosed.

ExchangeDownloadBuildKBSupersedes
Exchange 2019 CU11Download15.2.986.22KB5012698KB5008631
Exchange 2019 CU10Download15.2.922.27KB5012698KB5008631
Exchange 2016 CU22Download15.1.2375.24KB5012698KB5008631
Exchange 2016 CU21Download15.1.2308.27KB5012698KB5008631
Exchange 2013 CU23Download15.0.1497.33KB5010324KB5008631

Finally, KB5010324 also contains the following additional fix for Exchange 2013:

  • 5012925 RFC certificate timestamp validation in Exchange Server 2013

Be advised that these security updates are Cumulative Update level specific. You cannot apply the update for Exchange 2019 CU11 to Exchange 2019 CU10. Also, the security update download has the same name for different Cumulative Updates, and I would suggest tagging the file name with the CU level, e.g. Exchange2019-CU10-KBXXXXXX-x64-en.msp.

As a reminder, run the Security Update from an elevated command prompt to prevent issues during installation. In other words: Do not just double-click on the .MSP file. And on a final note, as with any patch or update, I’d recommend to apply this in a test environment first, prior to implementing it in production. However, it is not recommended to wait for regular maintenance cycles when it concerns security updates, and follow a more agile approach; the ratings are an indication of the urgency.

Security Updates Exchange 2013-2019 (Jan2022)

Another year, another Patch Tuesday! A quick blog on January 2022’s security updates for Exchange Server 2013 up to 2019.

The vulnerabilities addressed in these security updates are:

VulnerabilityCategorySeverityRating
CVE-2022-21969Remote Code ExecutionImportantCVSS:3.1 9.0 / 7.8
CVE-2022-21855Remote Code ExecutionImportantCVSS:3.1 9.0 / 7.8
CVE-2022-21846Remote Code ExecutionCriticalCVSS:3.0 9.0 / 7.8

Vulnerabilities mentioned in the table above are addressed in the following security updates.

ExchangeDownloadBuildKBSupersedes
Exchange 2019 CU11Download15.2.986.15KB5008631KB5007409
Exchange 2019 CU10Download15.2.922.20KB5008631KB5007409
Exchange 2016 CU22Download15.1.2375.18KB5008631KB5007409
Exchange 2016 CU21Download15.1.2308.21KB5008631KB5007409
Exchange 2013 CU23Download15.0.1497.28KB5008631KB5007409

More detailed information can be found at the original blog post here. The security update also fixes the OWA redirection problem for Exchange hybrid deployments introduced with the November security updates.

Be advised that these security updates are Cumulative Update level specific. You cannot apply the update for Exchange 2019 CU11 to Exchange 2019 CU10. Also, the security update download has the same name for different Cumulative Updates, and I would suggest tagging the file name with the CU level, e.g. Exchange2019-CU10-KBXXXXXX-x64-en.msp.

As a reminder, run the Security Update from an elevated command prompt to prevent issues during installation. In other words: Do not just double-click on the .MSP file. And on a final note, as with any patch or update, I’d recommend to apply this in a test environment first, prior to implementing it in production. However, it is not recommended to wait for regular maintenance cycles when it concerns security updates, and follow a more agile approach; the ratings are an indication of the urgency.

Managed AutoResponder Notifications

A long overdue blog on a solution which was created per request of an Exchange fellow. The original scenario is an organization spinning off, thereby changing their primary e-mail domain. They wanted to inform relations and partners using the old e-mail addresses of this change. However, this solution might also be helpful to organizations after merger and acquisitions or rebranding.

For the sake of the example, let us suppose Fabrikam was acquired by Contoso. Targeted mailboxes are migrated from the Fabrikam tenant to the Contoso tenant. Fabrikam will contain Mail-Enabled Users forwarding messages to their Contoso mailbox counterparts. The migrated mailboxes now hosted in Contoso will be configured to send notifications to senders which sent mail to the old Fabrikam address.

While organizations can resort to 3rd party tools to set up an Exchange Transport Rule with a generic message, a little script might also do the job, offering a more granular and controlled solution.

Solution
The scripted solution is available on GitHub here. It will configure an Inbox rule on the targeted Exchange mailbox(es), which would be the new/migrated mailbox. The rule will trigger when messages land in the inbox which were sent to a specific e-mail address, i.e. the previous e-mail address. It will send out an automatic response, which can consist of a custom subject, message body with an optional embedded image. The configuration of the response is defined in an customizable external XML file:

<?xml version="1.0" encoding="ISO-8859-1"?>  
<config>
  <rule>Contoso Autoresponder</rule>
  <subject>Please update your email recipient to Contoso</subject>
  <body>Dear Sender,

Thank you for your message. Fabrikam is now a whole Contoso subsidiary, and the fabrikam.com e-mail address will change to contoso.com. Your e-mail was forwarded to my new e-mail address. 

Please update contact information, distribution lists, etc. to update [OldMail] e-mail references with my new [Identity] e-mail address. 
 
[logo] 
The Contoso Corporation is a multinational business with its headquarters in Paris.</body>
  <logo>Contoso.png</logo>
</config>

The elements that can be used in the config are:

  • <rule> defines the name of the Inbox rule to be created. When the script runs, it will update any existing previously created inbox rules of the same name.
  • <subject> defines the subject of the response.
  • <body> defines the message body. You can use the following macros here:
    • [OldMail] will get replaced with the original e-mail address.
    • [Identity] will get replaced with the new e-mail address.
    • [Logo] will get replaced with the embedded image.
  • Optionally, <logo> refers to the file name of the image to embed.

Requirements
To run the script, you need the following:

  • Exchange Server 2013 SP1 or later, or Exchange Online.
  • Exchange Web Services (EWS) Managed API 2.21 or later (how to, NuGet package exchange.webservices.managed.api).
  • When using modern authentication or OAuth2, the MSAL library is required (NuGet package Microsoft.Identity.Client). Also, you need to have registered an App in Azure Active Directory with sufficient permissions (e.g. full_access_as_app). After registering the app, Tenant ID, Application ID and certificate or secret is what you need to use with the script to run successfully.
  • In addition to installing the NuGet packages, you can also store their DLLs in the same folder as the script for portability.

Usage
The syntax to run the script is as follows:

.\Set-AutoResponderNotification.ps1 -Identity <Identity> -TemplateFile <File> [-TenantId <TenantId> -ClientId <ClientId> [-CertificateThumbprint <ThumbPrint>] [-CertificateFile <File> -CertificatePassword <SecureString>] [-Secret <SecureString>]] [-Credentials <PSCredential>] [-Clear] [-Overwrite] [-Impersonation] [-TrustAll]

The available parameters and switches are as follows:

  • Identity specifies one or more e-mail addresses of mailboxes to process. Identity supports the pipeline (see examples).
  • OldMail specifies one or more old e-mail addresses to use when configuring the autoresponder message. When specifying multiple identities,
    the number of OldMail entries need to match the number of identities.
  • Server specifies the Exchange Web Services endpoint, for example outlook.office365.com for Exchange Online. When omitted, Autodiscover will be used.
  • Impersonation to use impersonation when accessing the mailbox. When using modern authentication, impersonation is mandatory.
  • TrustAll to accept all certificates including self-signed certificates.
  • TenantId specifies the ID of the Tenant when using a mailbox hosted in Exchange Online.
  • ClientId to specify the Application ID of the registered application in Azure Active Directory.
  • Credentials to specify the Basic Authentication credentials for on-premises usage or against Exchange Online when modern authentication is not an option.
  • CertificateThumbprint is the thumbprint of the certificate to use for modern authentication. The certificate with the public key needs to stored with the registered application for authentication. The certificate with the private key should be present in the local certificate store.
  • CertificateFile and CertificatePassword can be used to specify a certificate file to use. The file should contain the private key; the password protecting the certificate file can be specified using CertificatePassword as a secure string.
  • Secret can be used to specify the secret to authenticate using the registered application. The secret needs to be provided as a secure string.
  • Template
    specifies the XML template file to use when configuring or clearing the autoresponder inbox rule. The format has explained above.
  • Clear specifies if any you want to remove the inbox rules with name specified in the template. Use this when you want to remove autoresponder rules from mailboxes. When using Clear, you don’t need to specify OldMail.
  • Overwrite specifies if any existing inbox rules with name specified in the template should be overwritten. When omitted, the script will skip processing
    mailboxes with inbox rules with conflicting names. Use this when you want to configure the autoresponder only on mailboxes which do not have the rule.

Note that usage of the Verbose, Confirm and WhatIf parameters are supported.

Examples
Nothing more explanatory than an example. When we want to configure the autoresponder on a single mailbox, we can use something like:

image

Here, the autoresponder will get configured on the specified mailbox, triggering when mail has been sent to michel@fabrikam.com using the configuration defined in template.xml. Modern authentication will be used for authentication, using variables for Tenant, Client and in this case secret.

When you want to configure autoresponder for multiple mailboxes, you can for example use a CSV file. It needs to contain two elements which will be passed through pipeline, Identity and OldMail:

Identity,OldMail
philip@contoso.com,p.mortimer@fabrikam.com
francis@contoso.com,f.blake@fabrikam.com

After defining the response in a file template.xml, we can use this CSV to configure inbox rules on the Contoso mailboxes identified by Identity, triggering when mail is sent to their OldMail addresses:

Import-CSV -Path Users.csv | .\Set-AutoResponderNotification.ps1 -Server outlook.office365.com -Impersonation -TemplateFile .\Template.xml -TenantId <TenantId> -ClientId <ClientId> -Overwrite -CertificateThumbprint <Thumbprint>

What will happen is that for every set of Identity and OldMail, the mailbox specified by Identity will be configured with an inbox rule. When an existing rule is found, which is determined using the <rule> element in the XML template, it will get overwritten. The specified certificate will be picked from the local certificate store to authenticate against Tenant with TenantId, as application specified by ClientId.

Note that when the user opens Manage Rules & Alerts in Outlook, the configured inbox rule will be visible. This allows the user to remove it when it is no longer required. After a certain period, administrators can centrally remove these rules as well running the script using the Clear switch.

image

And finally, an example of how this may looks to senders when they receive an autoresponse message, using the sample configuration from the beginning of this article.

image

Application Access Policy
When using the script with modern authentication, you can leverage features such as conditional access to set boundaries for script usage. Also, you can configure application access policies to scope the registered app (script) to a subset of mailboxes. To accomplish this, assign an ApplicationAccessPolicy to the app.

To be more convenient in managing permissions, you can define a distribution group and assign the Application Access Policy with group scope (PolicyScopeGroupId). You then only need to add/remove members as you need to configure mailboxes.

More information about Application Access Policies here. Note that the permissions mentioned to not include full_access_as_app as permission, but it works.

EWS, why not Graph?
Microsoft already announced back in 2018 that development on Exchange Web Services will halt in and focus will shift to Graph. As part of this move, a more recent statement announced deprecation of some least-used API per March 2022, stimulating organizations to switch to using Graph. However, the organization looking for a solution wished for an automatic response with HTML as well as an embedded logo. Because of this, I had to use a template as a reply action.

But where Exchange Web Services supports reply with a template, Graph does not offer this functionality. So, until there is more feature parity between Exchange Web Services and Graph, or EWS goes completely out of service, solutions may still be forced to have a look at EWS for certain tasks.

Security Updates Exchange 2013-2019 (Nov2021)

Another month, another Patch Tuesday! A quick blog on November’s security updates for Exchange Server 2013 up to 2019. The vulnerabilities addressed in these security updates are:

VulnerabilityCategorySeverityRating
CVE-2021-42321Remote Code ExecutionImportantCVSS:3.1 8.8 / 7.7
CVE-2021-42305SpoofingImportantCVSS:3.1 6.5 / 5.7
CVE-2021-41349SpoofingImportantCVSS:3.1 6.5 / 5.7

Vulnerabilities mentioned in the table above are addressed in the following security updates. Exception is Exchange 2013 CU23 which seemingly only gets fixed for CVE-2021-26427; it is unclear if that is because of Exchange 2013’s lifecycle phase or because the problem does not exist in those builds.

ExchangeDownloadBuildKBSupersedes
Exchange 2019 CU11Download15.2.986.14KB5007409KB5007012, KB5007011
Exchange 2019 CU10Download15.2.922.19KB5007409KB5007012, KB5007011
Exchange 2016 CU22Download15.1.2375.17KB5007409KB5007012, KB5007011
Exchange 2016 CU21Download15.1.2308.20KB5007409KB5007012, KB5007011
Exchange 2013 CU23Download15.0.1497.26KB5007409KB5007012, KB5007011

More detailed information can be found at the original blog post here. Check the KB articles for any known release notes, such as the possible cross-forest Free/Busy issue and HTTP headers containing version information.

Be advised that these security updates are Cumulative Update level specific. You cannot apply the update for Exchange 2019 CU11 to Exchange 2019 CU10. Also, the security update download has the same name for different Cumulative Updates, and I would suggest tagging the file name with the CU level, e.g. Exchange2019-CU10-KBXXXXXX-x64-en.msp.

As a reminder, run the Security Update from an elevated command prompt to prevent issues during installation. In other words: Do not just double-click on the .MSP file. And on a final note, as with any patch or update, I’d recommend to apply this in a test environment first, prior to implementing it in production. However, it is not recommended to wait for regular maintenance cycles when it concerns security updates, and follow a more agile approach; the ratings are an indication of the urgency.

Security Updates Exchange 2013-2019 (Oct2021)

Welcome to another Patch Tuesday! A quick blog on October’s security updates for Exchange Server 2013 up to 2019.

The vulnerabilities addressed in these security updates are:

VulnerabilityCategorySeverityRating
CVE-2021-26427Remote Code ExecutionImportantCVSS:3.0 9.0 / 7.8
CVE-2021-41350SpoofingImportantCVSS:3.0 6.5 / 5.7
CVE-2021-41348Elevation of PrivilegeImportantCVSS:3.0 8.0 / 7.0
CVE-2021-34453Denial of ServiceImportantCVSS:3.0 7.5 / 6.5

Vulnerabilities mentioned in the table above are addressed in the following security updates. Exception is Exchange 2013 CU23 which seemingly only gets fixed for CVE-2021-26427; it is unclear if that is because of Exchange 2013’s lifecycle phase or because the problem does not exist in those builds.

ExchangeDownloadBuildKBSupersedes
Exchange 2019 CU11Download15.2.986.9KB5007012
Exchange 2019 CU10Download15.2.922.14KB5007012
Exchange 2016 CU22Download15.1.2375.12KB5007012
Exchange 2016 CU21Download15.1.2308.15KB5007012
Exchange 2013 CU23Download15.0.1497.24KB5007011

More detailed information can be found at the original blog post here. Check the KB articles for any known release notes, such as the possible cross-forest Free/Busy issue and HTTP headers containing version information.

Be advised that these security updates are Cumulative Update level specific. You cannot apply the update for Exchange 2019 CU11 to Exchange 2019 CU10. Also, the security update download has the same name for different Cumulative Updates, and I would suggest tagging the file name with the CU level, e.g. Exchange2019-CU10-KBXXXXXX-x64-en.msp.

As a reminder, run the Security Update from an elevated command prompt to prevent issues during installation. In other words: Do not just double-click on the .MSP file. And on a final note, as with any patch or update, I’d recommend to apply this in a test environment first, prior to implementing it in production. However, it is not recommended to wait for regular maintenance cycles when it concerns security updates, and follow a more agile approach; the ratings are an indication of the urgency.

Exchange Updates – September 2021

The Exchange Team released the quarterly Cumulative Updates for Exchange Server 2019 as well as Exchange 2016.

Be advised that these CUs will introduce something which is called the Exchange Emergency Mitigation Service. This service is designed to distribute and implement mitigations addressing potential threats. For this, the URL Rewrite Module needs to be installed on the Exchange server. When you have Exchange running on Windows Server 2012 R2, you will also need an update for the Universal C Runtime (KB2999226). Periodically, the EEM service will reach out to the Office Config Service (OCS) through endpoint https://officeclient.microsoft.com, and update its set of configured mitigations. More on EEM and managing its configuration here.

Links to the updates as well as a description of changes and fixes are described below. The column Schema and AD indicate if the CU contains Schema (/PrepareSchema) and Active Directory (PrepareAD) changes compared to the previous CU. Refer to the Exchange Schema page for schema and related versioning information.

VersionBuildKBDownloadUMLPSchemaAD
Exchange 2019 CU1115.2.986.5KB5005334Download NY
Exchange 2016 CU2215.1.2375.7KB5005333DownloadUMLPNY

Exchange 2019 CU11 fixes:

  • 5006980 Bad signature error using PerfView in Exchange Server 2019 and 2016 (KB5006980)
  • 5006982 On-premises Exchange queues back up because of incorrect default value (KB5006982)
  • 5006983 Exchange Server 2019 and 2016 certificates created during setup use SHA-1 hash (KB5006983)
  • 5006984 PrepareAD fails if Computers container or RODCs are renamed or moved in Exchange Server 2019 and 2016 (KB5006984)
  • 5006986 Opening an Outlook message from the desktop removes line spacing (KB5006986)
  • 5006988 Export of .pst file is unexpectedly triggered again in Exchange Server 2019 and 2016 (KB5006988)
  • 5006989 Accepted domains with wildcards for subdomains are not honored when Edge server maps AddressSpaces (KB5006989)
  • 5006990 Exchange CU installation fails after you configure fallback to use default character set (5006990)
  • 5006991 Mail quota warning messages no longer sent daily in Exchange Server 2019 (KB5006991)
  • 5006992 No room lists found when trying to add a room in OWA in Exchange Server 2019 or 2016 (KB5006992)
  • 5006993 Can’t log on to OWA in Chrome if SSL is offloaded in Exchange Server 2019 and 2016 (KB5006993)
  • 5006994 BCC values not retained in Sent Items in a shared mailbox in Exchange Server 2019 and 2016 (5006994)
  • 5006995 Korean email messages display some recipients incorrectly in Exchange Server 2019 and 2016 (KB5006995)
  • 5006996 Export-AutoDiscoverConfig exposes admin password and does not work against domain controllers that require signing (KB5006997)
  • 5006997 Korean messages in OWA display “From” as “Start date” after you filter the list in Exchange Server 2019 and 2016
  • 5006999 “401” error and Outlook repeatedly prompts for credentials in Exchange Server 2019 (KB5006999)
  • 5007042 Error window appears when you view features in OWA Virtual Directory (KB5007042)
  • 5007043 Exchange Server SU updates Add/Remove Programs incorrectly (KB5007043)
  • 5007044 Start-MailboxAssistant not available in EMS in Exchange Server 2019 (KB5007044)

Exchange 2016 CU22 fixes:

  • 5006980 Bad signature error using PerfView in Exchange Server 2019 and 2016 (KB5006980)
  • 5006982 On-premises Exchange queues back up because of incorrect default value (KB5006982)
  • 5006983 Exchange Server 2019 and 2016 certificates created during setup use SHA-1 hash (KB5006983)
  • 5006984 PrepareAD fails if Computers container or RODCs are renamed or moved in Exchange Server 2019 and 2016 (KB5006984)
  • 5006986 Opening an Outlook message from the desktop removes line spacing (KB5006986)
  • 5006988 Export of .pst file is unexpectedly triggered again in Exchange Server 2019 and 2016 (KB5006988)
  • 5006989 Accepted domains with wildcards for subdomains are not honored when Edge server maps AddressSpaces (KB5006989)
  • 5006992 No room lists found when trying to add a room in OWA in Exchange Server 2019 or 2016 (KB5006992)
  • 5006993 Can’t log on to OWA in Chrome if SSL is offloaded in Exchange Server 2019 and 2016 (KB5006993)
  • 5006994 BCC values not retained in Sent Items in a shared mailbox in Exchange Server 2019 and 2016 (5006994)
  • 5006995 Korean email messages display some recipients incorrectly in Exchange Server 2019 and 2016 (KB5006995)
  • 5006996 Export-AutoDiscoverConfig exposes admin password and does not work against domain controllers that require signing (KB5006997)
  • 5006997 Korean messages in OWA display “From” as “Start date” after you filter the list in Exchange Server 2019 and 2016
  • 5007042 Error window appears when you view features in OWA Virtual Directory (KB5007042)
  • 5007043 Exchange Server SU updates Add/Remove Programs incorrectly (KB5007043)

Notes:

  • If these Cumulative Updates contain schema changes compared to the Cumulative Update you have deployed, you need to run Setup with /PrepareSchema. If they contain Active Directory changes, you need to run /PrepareAD. Alternatively, permissions permitting, you can let Setup perform this step. Consult the Exchange schema versions page for schema and related versioning information.
  • 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), support requires you to trail 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 upgraded, you can’t uninstall a Cumulative Update nor any of the installed Exchange server roles.
  • The recommended upgrade order is 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.

Unarchiving Mailbox Items

With the introduction of Exchange 2010 at the end of 2009, a native feature was added to Exchange Server for which organizations required 3rd party products before that. The feature which I am talking about is Exchange’s Personal Archives, Online Archives, or In-Place Archiving as it is called nowadays.

Background
Archives were introduced at a time when Office 365 was in its early days, many organizations were running Exchange on-premises with mailbox quotas as bandwidth and storage were limited or relatively expensive. It was up to end users to make sure their mailbox remained within its limits, either by removing either old items, large items or just move them out of their mailbox to those pesky .PST files.

Archives introduced benefits such as lowering disk footprint by taking infrequently used items out of the primary mailbox (which then could only synchronize in full) to the archive, which is basically an additional mailbox for long-term storage. Exchange’s built-in Messaging Records Management (MRM) through retention policies and tags can be used for automatic moving of older items to the archive.

Archives also come with few downsides, especially in the early days. Most notably are perhaps clients not supporting archives at all, or searches not spanning both mailbox and archive. Also, and this is not to be underestimated, end users do not always grasp the concept of archives and the impact on the tasks and tools they use. It’s not uncommon to see people panicking about “missing data” in service tickets, only to discover their “missing data” was moved to their archive by the company retention policy after some digging.

In recent years, I have seen archives becoming less relevant, and organizations adopting the large mailbox concept in favor of lean and mean mailboxes with archives. There are still exceptions of course, usually in the form of substantial – usually shared – mailboxes. For those, staying with Exchange Online archives – and when needed auto-expanding archives – is usually still an option due to the different type of mailbox interaction, or to circumvent Exchange’s storage limitations or Outlook for Desktop’s synchronizing of offline cache files before issues might be seen. The maximum number of items per folder is such a limit, however these have been raised or done away with in recent years. Non-stubbing 3rd party archive solutions taking data out of Exchange can also be a option.

The Problem
Switching to the large mailbox concept creates a problem for those organizations that have already enabled in-place archives for their end users: How to get that data back from those archives to the primary mailbox. While retention policies can move data in opposite direction, there is no such thing as a reverse-retention policy. Also, not every organization would like to instruct end users to unarchive this contents themselves, as it is prone to failure, blocks Outlook for Desktop from doing anything else and might result in abandoned operations which limits future actions as moves are still happening in the background.

When investigating a possible solution I found that there is no other way to accomplish this, than to programmatically move contents from the in-place archive to the primary mailbox. While there is a ‘archive’ operation for mailbox items (which moves it to the assigned Archive folder, not the in-place archive) there is no other single API call to perform this task. Also, the solution would have to use Exchange Web Services, as a limitation in Microsoft Graph makes it incapable of moving messages between multiple mailboxes.

Note: If I overlooked something in this area, please let me know.

Solution
To help organizations accomplish this task, I wrote a PowerShell script which requires the following:

  • Exchange Server 2013 SP1 or later, or Exchange Online.
  • Exchange Web Services (EWS) Managed API 2.21 or later (how to, NuGet package exchange.webservices.managed.api).
  • When using OAuth, the MSAL library is required (NuGet package Microsoft.Identity.Client). Also, you need to have registered an App in Azure Active Directory; the Tenant ID, Application ID and certificate or secret is what you need to provide the script with to operate successfully.
  • In addition to installing the NuGet packages, you can also store the DLLs in the same folder as the script.

Note: Untested with Primary mailboxes on-premises and Exchange Online Archives.

The script Invoke-Unarchive will perform the following tasks:

  • Invoke-Unarchive will move contents from the in-place archive back to the primary mailbox.
  • The most optimal operation will be chosen:
    • Folders present in archive but not in primary mailbox will be moved in one operation.
    • Folders present in archive and primary mailbox are merged. Items in those folders are moved in batches.
    • The same steps are repeated recursively per folder for the whole archive.
  • If, after moving, a folder in the archive is empty, and it is not a non-removable well-known folder, it will be removed.
  • Optionally, Invoke-Unarchive can also move contents stored in the Recoverable Items from the archive to the primary mailbox.
  • Invoke-Unarchive will handle throttling, either by honoring the returned back-off period or by adding delays between operations.
  • Moving items is asynchronous, and Invoke-Unarchive needs to wait for Exchange to complete the previous move to folder X before it can move the next set of items to folder X.

Do not forget to reassign retention policies causing archival, or you might have the run the script again at later moment.

Syntax
The parameters to call Invoke-Unarchive.ps1 are:

  • Identity to specify one or more mailboxes to unarchive items for.
  • Server to specify the FQDN of the Client Access Server to use. When omitted, Autodiscover will be used.
  • IncludeRecoverableItems to instruct the script to process deletions stored in the Recoverable Items as well.
  • Impersonation to use impersonation when accessing the mailbox. When using modern authentication (OAuth), impersonation is mandatory.
  • Force to force moving of items without prompting.
  • NoProgressBar to prevent progress status.
  • TrustAll to accept all certificates including self-signed certificates.
  • TenantId specifies the ID of the Tenant when using a mailbox hosted in Exchange Online.
  • ClientId to specify the Application ID of the registered application in Azure Active Directory.
  • Credentials to specify the Basic Authentication credentials for on-premises usage or against Exchange Online when OAuth is not an option.
  • CertificateThumbprint is the thumbprint of the certificate to use for OAuth. The certificate with the public key needs to stored with the registered application for authentication. The certificate with the private key should be present in the local certificate store.
  • CertificateFile and CertificatePassword to specify the file of the certificate to use. The file shoud contain the private key, and the password to unlock the file can be specified using CertificatePassword.
  • Secret can be used to specify the secret to authenticate using the registered application.

Note that Credentials, CertificateThumbprint, CertificateFile + CertificatePassword and Secret are mutually exclusive.

Example
Below shows an example run against a test-mailbox using modern authentication (OAuth). The common parameter Verbose is used to display additional output.

.\Invoke-Unarchive.ps1 -Identity michel@myexchangelabs.com -Server outlook.office365.com -Impersonation -Secret <Secret> -TenantId <Tenant> -ClientId <AppId> -Verbose
image

You can find the script on GitHub here.

Final Notes
The EWS operation – especially moving items – is not necessarily slow, but against Exchange Online processing large archives can take considerable amount of time due to throttling. When moving a significant number of items using Outlook for Desktop, you will likely run into Outlook abandoning the operation after which you need to wait for Exchange to finish pending moves before you can continue with this task. Using the script, you can take away this unarchiving task from end users by running the operation in the background in one or multiple runs.

Security Updates Exchange 2013-2019 (Jul2021)

Update July 20th: Added VC++2012 requirement to tip on running MT to prepare Exchange 2013 schema separately.

Another month, another Patch Tuesday! A quick blog on the July’s security updates for Exchange Server 2013 up to 2019.

The vulnerabilities addressed in these security updates are:

VulnerabilityCategorySeverityRating
CVE-2021-31196Remote Code Execution ImportantCVSS:3.0 7.2 / 6.3
CVE-2021-34470Elevation of PrivilegeImportantCVSS:3.0 8.0 / 7.0
CVE-2021-33768Elevation of PrivilegeImportantCVSS:3.0 8.0 / 7.0
CVE-2021-31206Remote Code ExecutionImportantCVSS:3.0 7.6 / 7.1

Note:

  • When looking at the MSRC information, you will notice 3 additional CVE issues addressed for July 13th. However, as far as I can see CVE-2021-34473, CVE-2021-34523 and CVE-2021-33766 were addressed in the April 2021 and eventually the May 2021 Security Updates, which also would explain MSRC’s mention of earlier CUs, such as Exchange 2019 CU8.
  • CVE-2021-31206 was the vulnerability discovered at the Pwn2Own 2021 contest.

Vulnerabilities mentioned in the table above are addressed in the following security updates:

ExchangeDownloadBuildKBSupersedes
Exchange 2019 CU10Download15.2.922.13KB5004780
Exchange 2019 CU9Download15.2.858.15KB5004780
Exchange 2016 CU21Download15.1.2308.14KB5004779
Exchange 2016 CU20Download15.1.2242.12KB5004779
Exchange 2013 CU23Download15.0.1497.23KB5004778

Notes:

  • CVE-2021-33768 does not seem applicable to Exchange 2019 CU9 or Exchange 2016 CU20.
  • CVE-2021-34470 is only addressed in the security update for Exchange 2013 CU23.

More detailed information can be found at the original blog post here, which mentions some specific post-deployment instructions:

  • When running n-1 CU of Exchange 2019 (CU9) or Exchange 2016 (CU20), and you do not plan to upgrade to the latest CU yet but do wish to install this Security Update, you must also update the AD Schema using the CU10 or CU21 installation files.
  • When you are running Exchange 2013 CU23 in your organization, and no later Exchange builds are present, you need to deploy a schema update immediately after deploying the Security Update. After deploying the SU, from an elevated CMD prompt, run Setup.exe /PrepareSchema /IAcceptExchangeServerLicenseTerms from Exchange’s bin folder. You you need to separate the update from deploying the update, see end of article for a tip.

The blog also mentions some issues, which are identical to the ones mentioned with the May 2021 Security Updates:

  • Accounts ending in ‘$’ cannot use EMS or access the ECP.
  • Cross-forest Free/Busy might stop working resulting in 400 Bad Request (solution).
  • Running cmdlets against EMC using invoked runspace might result in no-language mode error (info).

Be advised that these security updates are Cumulative Update level specific. You cannot apply the update for Exchange 2019 CU9 to Exchange 2019 CU8. Also, the security update download has the same name for different Cumulative Updates, and I would suggest tagging the file name with the CU level, e.g. Exchange2019-CU9-KBXXXXXX-x64-en.msp.

On another note, after deploying the security updates Exchange will start reporting its version number in the HTTP response header.

As a reminder, run the Security Update from an elevated command prompt to prevent issues during installation. In other words: Do not just double-click on the .MSP file. And on a final note, as with any patch or update, I’d recommend to apply this in a acceptance environment first, prior to implementing it in production. However, it is not recommended to wait for regular maintenance cycles when it concerns security updates, and follow a more agile approach. The rating implies a form of urgency.

OWA/ECP and HMAC errors
There are reports of the Security Update breaking OWA/ECP. Symptoms are browsers displaying an HMAC error:

Server Error in '/owa' Application.

ASSERT: HMACProvider.GetCertificates:protectionCertificates.Length<1
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
    
Exception Details: Microsoft.Exchange.Diagnostics.ExAssertException: ASSERT: HMACProvider.GetCertificates:protectionCertificates.Length<1

It is likely related to “Microsoft Exchange Server Auth Certificate”, which can be expired, invalid or for other reasons not being picked up. The reported solution is renewing the “Microsoft Exchange Server Auth Certificate”. This procedure can be found here. Do note that it may take an hour for the certificate to become effective. Meanwhile, you can check the comments in the original Exchange Team post, which is lively with feedback and responses.

Exchange 2013 CU23 SU & Schema Updating
Because with Exchange 2013 CU23 schema preparation needs to occur immediately after deploying the SU on (the first) Exchange 2013 CU23 server, a tip might be that you could deploy Exchange 2013 CU23 Management Tools on a workstation, install the SU on that workstation, then run the PrepareSchema from there before deploying the SU on any Exchange 2013 CU23 server.

This might also be helpful in multi-domain organizations, or organizations where AD and Exchange are managed by different teams or require separate changes. Note that performing the schema update this way requires Visual C++ 2012 Runtime, otherwise you will run into a “Exchange Server setup didn’t complete the operation” and the ExchangeSetup.log will contain “Could not load file or assembly ‘Microsoft.Exchange.CabUtility.dll”.