This is a text-only version of the following page on https://raymii.org: --- Title : Exchange 2010 - OWA - Lock user after x amount of failed logins Author : Remy van Elst Date : 19-12-2012 URL : https://raymii.org/s/tutorials/Exchange_2010_OWA_lock_users_after_x_amount_of_failed_logins.html Format : Markdown/HTML --- This is a tutorial to set up automatic user lockout in Exchange 2010 - Outlook Web Acces (OWA). When a user does 5 wrong login attempts, he/she is locked out from the webinterface. After for example 5 minutes he or she is unlocked again automatically. This helps you mitigate brute force attacks, since an attacker can only try 1 password/minute, but the user will not be blocked for to long. Exchange 2010 has some special register settings to make IIS stop caching, otherwise it would not work.

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#### Group Policy settings Execute the following steps on one of your domain controllers. `Start` -> `Administrative Tools` -> `Group Policy Editor`. Right click the "Default Domain Policy" (or any other policy where you might want to apply this). Click `Edit` Navigate to: `Computer Configuration` -> `Policies` -> `Windows Settings` -> `Security Settings` -> `Account Policies` -> `Account Lockout Policy`. Set the following values: - "Account Lockout Duration": 5 minutes - "Account Lockout Threshold": 5 invalid logon attempts - "Reset Account Lockout Counter After": 5 minutes Adapt this to your own time/threshold if you feel so. Also make sure the group policy is enforced. Lets move on to IIS to make sure that OWA does not cache the login token. ### IIS / OWA Outlook Web Access operates via the IIS server, which when using form based authentication caches login tokens for a set amount of time. [(See this link)][2] and [this one][3]. If you have set the above group policy and you test in on the outlook web access of the exchange server, you will notice that if you have done more than 5 failed logins you can still login with the good password. On your IIS server(s) where OWA resides execute the following: Click `Start` Click `Run` Type: `regedit` Navigate to the following key: `HKEY_LOCAL_MACHINESystemCurrentControlSetServicesInetInfoParameters` Click the `Edit` menu, then the `Add` menu, select a `32 bit DWORD` (or just `DWORD`). Name it: `UserTokenTTL` Then set its value to `30`. This means that user tokens will be cached for 30 seconds by IIS. Now that is also solved. ### Bonus: Active Directory Saved Search to view Locked Out users Open the `Active Directory Users && Computers` window from the `Administrative Tools` menu. Right Click the `Saved Queries`, select `New` -> `Query`. Name: `Locked Out users` Description: `-` Click `Define Query`. Click the `Find` dropdown, select `Custom Search`. Select the `Advanced` tab. Paste the following LDAP Query: (&&(&&(&&(objectCategory=Person)(objectClass=User)(lockoutTime>=1)))) Click `OK`. Click `OK`. Now if a users calls you that they cannot login, you can see if they are locked out via that Saved Search. (Note that you might have to refresh the view a few times before seeing it.) [1]: https://www.digitalocean.com/?refcode=7435ae6b8212 [2]: http://support.microsoft.com/kb/173658/en-us [3]: https://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/iis/6b2e7fcd-5fad-4ac8-ac0a-dcfbe771e9e1.mspx --- License: All the text on this website is free as in freedom unless stated otherwise. This means you can use it in any way you want, you can copy it, change it the way you like and republish it, as long as you release the (modified) content under the same license to give others the same freedoms you've got and place my name and a link to this site with the article as source. This site uses Google Analytics for statistics and Google Adwords for advertisements. You are tracked and Google knows everything about you. Use an adblocker like ublock-origin if you don't want it. All the code on this website is licensed under the GNU GPL v3 license unless already licensed under a license which does not allows this form of licensing or if another license is stated on that page / in that software: This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see . Just to be clear, the information on this website is for meant for educational purposes and you use it at your own risk. I do not take responsibility if you screw something up. Use common sense, do not 'rm -rf /' as root for example. If you have any questions then do not hesitate to contact me. See https://raymii.org/s/static/About.html for details.