Due to the vulnerability that allows privilege escalation I wrote about in this post, Microsoft has released a cumulative update for all supported versions of Exchange Server (Exchange 2010, 2013, 2016 and 2019).
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A new vulnerability that affects Exchange on-premise servers has been discovered recently (https://dirkjanm.io/abusing-exchange-one-api-call-away-from-domain-admin/). By making use of the high privileges Exchange servers have by default, the attacker would be able to escalate from any user with a mailbox to Domain Admin access.
According to Dirk-jan Mollema (see upper link), the vulnerability has been tested against …
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Symptom: Large mail.que file size
Last week my Icinga started alerting about low free space in my Exchange server disk.
After using a software to scan for file sizes I realized there was a too big mail.que file.
This is the file in which exchange manages its queues before finally delivering emails. It is usually located in <Exchange_Installation_Path>/TransportRoles/data/Queue
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Some days ago I tried to cleanup old certificates from my Exchange servers, but I received the following error:
[PS] C:\> Remove-ExchangeCertificate -Thumbprint D09EDD6D5F18C175254AB97046AAAAAAAAAAAAA
Are you sure you want to perform this action?
Remove certificate with thumbprint DD09EDD6D5F18C175254AB97046AAAAAAAAAAAAA from the computer's certificate store?
[Y] Yes [A] Yes to All [N] No [L] No to All [?] Help (default is
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In June 2018 Microsoft released Cumulative Update 21 (build 15.00.1395.004) which is the last planned quarterly update for Exchange 2013 (https://blogs.technet.microsoft.com/rmilne/2018/06/19/exchange-2013-cu21-released/)
I was not sure about updating my Exchange 2013 directly from CU12 to CU21. It is supposed to be supported by Microsoft. Maybe I could install an intermediate CU before but, anyway, I decided to move on.… Read more
I needed to install .NET 4.7.1 to allow updating Exchange 2013 to CU 21.
This is the installer I downloaded and tried to install: https://www.microsoft.com/en-us/download/details.aspx?id=56116
But the installation never ends. It remains stuck without progressing in the “Installation progress” bar. Tested both with offline and online installation:
To install .NET Framework 4.7.1 download the msu package from the following link:… Read more
When performing mailbox migrations using the New-MoveRequest, the movement is performed online while the user is using the mailbox without suffering outage until the end.
Only when completing the movement there are some seconds during which the user mailbox is not online.
Thats the reason to use the parameter “SuspendWhenReadyToComplete“. It moves almost all the mailbox except the … Read more
A user asked me the way to grant permissions to other users to access to some of his mailbox folders. And for certain folder only read-only permissions.
Let’s suppose “testuser1” wants to allow accessing some folders to “testuser2”.
Permission configuration (Outlook)
First of all, “testuser2” must have “Reviewer” (read-only) permissions on the mailbox root
Then, configure the permission … Read more
Last week I was testing the IMAP/SMTP connection of my Exchange 2013. Unexpectedly Outlook returned the following error:
The message does not appear completely but seems to be “550 5.7.1 Client does not have permissions to send as this sender”. Obviously the user does have the permissions (the user was the owner of the mailbox itself).
Thanks … Read more
Exchange 2013 can produce IMAP issues when trying to authenticate. This is a known bug in CU9 and CU10 but in my CU12 scenario also happens.
The IMAPSettings EnableGSSAPIAndNTLMAuth atribute must be set to False in order to solve the problem.
Yesterday, when one of my users asked me how to configure the email client using IMAP I realized … Read more