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Methods to Secure Windows Remote Desktop RDP

How To Secure Windows Remote Desktop

In September 2018 the FBI issued a public service announcement regarding risks and hacking attempts again the RDP protocol.  See the announcement here which includes some suggestions (with additional considerations below) https://www.ic3.gov/media/2018/180927.aspx

Considerations For Securing your Windows Server / RDP Terminal Server

Here is a list of various actions to consider to help secure your remote server environment:

After applying any of the actions above, make sure to test whether they are working properly.  You can open multiple RDP sessions using different user names initiated from one PC which can be useful for testing.

 

The information provided in this document/post is intended to provide general information only and is not a complete listing of available considerations.  The content is provided AS IS without any express or implied warranties of any kind with respect to the accuracy, correctness, reliability, or fitness for a particular purpose.  You should be discussing all security policies and related procedures, configurations, monitoring and other server management functions with your IT staff or consultants.  Riptide Hosting does not provide managed services and is not a substitute for you maintaining your own IT staff/consultants. 

RD Session Host Security settings in Windows Server 2016

RD Session Host Security settings in Windows Server 2016 (SSL, High encryption, etc.)

Gpedit.msc, computer configuration, administrative templates, windows components, remote desktop services, remote desktop session host, security, see various options.

  • “Require use of specific security layer for remote (RDP) connections” – Changing Security Layer to SSL is the recommendation listed in Windows 2016,
  • “Client Connection Encryption Level to High” – enabled/Yes
  • “Require Secure RPC communication” – enabled/Yes
  • “Require user authentication for remote connections by using NLA” – enabled/Yes

Enable Group Policies to automatically logoff disconnected sessions or idle sessions after X minutes/hours

Enable Group Policies to automatically logoff disconnected sessions or idle sessions after X minutes/hours

Not only does this reduce server resources (ram/cpu) that are used up by disconnected sessions and affecting the overall performance of the remote desktop server, automatically logging off disconnected and idle sessions may help lessen risk if vulnerabilities in Windows are found that allow a user on one active session to access another active session.  See this post on how to enable policies to automatically logoff disconnected and idle sessions (highly recommended to do, and something we do by default now on new servers):

http://www.riptidehosting.com/blog/how-to-modify-timing-of-windows-updates-in-windows-server-2016-to-control-timing-of-updates-and-restarts/

RD Gateway Role in RDS

RD Gateway Role in RDS

Using the Remote Desktop Gateway Role (RDGW) provides additional security by forcing RDP traffic over https/port 443 (requires SSL certificate) instead of port 3389.

General steps to install the RDGW role on Windows Server 2016: (we have a more detailed post on this too)

  • Install RDGW role which will also install IIS
  • In RD Gateway Manager, create CAP and RAP policies for who can login to the gateway and what resources they can access.
  • For initial testing/deployment, you can create a self-signed certification and change the certificate name to IP address in the name field. Using a self-signed certificate will require you to install the certificate on each client device. Using a SSL cert issued by a certificate authority is preferred and can only be issued in the domain name, not IP address).
  • Confirm that all items in the RD Gateway Manager have green checkmarks.
  • From the RD Connection Client on your local PC, go to more options, advanced tab, enter gateway settings before connecting.
  • Turn off port 3389 to the outside on the Windows Firewall on the server to force traffic to use port 443.

Test deployment

Windows Server Lockout Policies

Lockout Policies (based on username attempts, not IP addresses):

To lock out an account for a period of time after a number of incorrect login attempts (to create delay with recurring failed logins), you can set up Account Lockout Policies in Windows.  It does NOT apply to the Administrator account (so you may want to disable the Administrator account and create a different account with administrator rights – see previous suggestion).  Lockout policies can be useful to prevent brute-force password guessing attacks but can cause your accounts to be locked out without you being able to access the server (so plan accordingly).

Local Security Policy (secpol.msc) -> Security Policies -> Account Policies -> Account Lockout Policy, set values for the three options, OR

Gpedit.msc -> Local Computer Policy -> Computer Configuration -> Windows Settings -> Security Policies -> Account Policies -> Account Lockout Policy, set values for the three options

To unlock an account, (if a legit user is locked out) login under an active account (with administrator properties), go to the locked out user’s properties, and uncheck the box by “account is locked out”.

You can see detailed status of a user account by opening the command prompt and typing “net user [username]”

Limit users who can login via RDP

Limit users who can login via RDP

By default, all users in the “Administrators group” have RDP access rights.  And, of course, all users in the “Remote Desktop Users group” have RDP access rights too.  If you only want some members of the Administrators group to have RDP access, you can adjust this in Local Security Settings as follows: by removing the “administrators group” and then making sure all required remote users are part of the “Remote Desktop Users group”.

Local Security Policy (secpol.msc) -> Security Settings -> Local Policies -> User Rights Assignment -> Allow Logon Through Remote Desktop Services, change settings to remove “Administrators group” (but make sure any users you want to have RDP access are already part of the “Remote Desktop Users Group” especially the one you are currently logged in with).

Change RDP Listening Port

Change RDP Listening Port from default 3389

Changing the RDP listening port to a non-default port may not defeat a determined hacker but it should reduce attacks from automated bots.  **Remember to create new firewall rules to allow the new port number so you don’t accidently lock yourself out.  And remember that end-users will need to add the new port # to the IP address/computer name when logging in, such as 123.456.78.888:5555 where the new listening port is 5555.  If you have MAC users, you should verify if the RD Client for MACs support a port other than 3389.

  • Change port in Registry first – http://support.microsoft.com/kb/306759 (older link but still should apply)
  • Regedit, then locate and click the following registry subkey: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\TerminalServer\WinStations\RDP-Tcp\PortNumber On the Edit menu, click Modify, and then click Decimal. Type the new port number, and then click OK. Quit Registry Editor.)
  • Create two new Windows Firewall rules (one for TCP and one for UDP) for the new port number. For example, in a administrative command prompt, type this to create two new inbound rules (tcp & upd) where 35000 is the new port you used in the registry change:

netsh advfirewall firewall add rule name=”Remote Desktop (TCP-In) 35000″ dir=in localport=35000 protocol=tcp action=allow

netsh advfirewall firewall add rule name=”Remote Desktop (UDP-In) 35000″ dir=in localport=35000 protocol=udp action=allow

You can compare these new rules to the existing rules in the firewall.

  • Reboot server
  • Then Login using new port number using :ZZZZ where ZZZZ is new RDP listening port – for example, 250.197.92.199:ZZZZ (and also test that 3389 to confirm it won’t work).
  • Disable previous RDP Firewall rules that allowed port 3389

Windows Server 2016 VPN

VPN

Using a VPN with RDP is more secure because it provides two steps to access your network.  You could require clients to connect with a VPN first before being able to RDP to the server.  Unless you are using our Dedicated Server Hosting offering where you can have a hardware vpn device, you will need to install a software VPN on the server.  One option is using the free built-in Windows VPN role service. Other software VPN options available have been Hamachi (acquired by LogMeIn), Zerotier which provides software defined networking capabilities, and other options.

 

WINDOWS SERVER BUILT-IN VPN ROLE:

If you are interested in setting up the built-in VPN role on Windows Server 2016 and then limiting RDP access to private IPs after VPN is connected, contact Riptide Hosting for a post we wrote on how to set this up.  PPTP VPN using Windows Authentication is password based so strong/complex passwords are still very important. Other VPN protocols, certificate authentication, may provide stronger security depending on your needs and environment.  You can use the built-in Windows VPN to setup a L2TP VPN with preshared keys too.

General steps to install the (free) built-in VPN role on Windows Server 2016:

  • Add “Remote Access” server role with “DirectAccess and VPN (RAS)” role service.
  • Open the Getting Started Wizard, select “Deploy VPN only”, “Configure and Enable Routing and Remote Access”, Select “Custom Configuration”, Select “VPN access” only. Start Service.  Reboot
  • Go into “Routing and Remote Access” properties, IPv4 tab to add static IP address pool with private IPs
  • Change Network Adapter settings, IPv4, to add secondary IP from private IP range above
  • Adjust User Properties for each user on the Dial-In tab to Allow “Network Access Permission”
  • Setup VPN Connection on each user PC (may need to uncheck “use default gateway on remote network” if having internet issues on the PC)
  • Adjust Server Firewall rules to disable RDP access on port 3389
  • Test deployment (verify you can’t RDP without using VPN first, etc.)
  • Our steps generally follow the steps in these links with a few additional items noted

https://www.thomasmaurer.ch/2016/10/how-to-install-vpn-on-windows-server-2016/

https://www.starwindsoftware.com/blog/how-to-install-vpn-access-on-windows-server-2016

Two-Factor / Dual-Factor Authentication

Two-Factor / Dual-Factor Authentication

There are several third-party software products available that enable two-factor authentication.  One third party software option is Duo Security (www.duo.com) which provides two-factor authentication for RDP access (and more) where you have to enter a code during RDP login that you receive on your smartphone first.  Duo has a free personal account for up to 10 users, trials and various other paid levels.

Disable built-in Administrator account

Disable built-in Administrator account (create alternative admin account)

All Windows Servers come with the built-in Administrator account (SID 500) by default and all administrator accounts have RDP access by default (when RDP is enabled overall).  Therefore the Administrator account, if port 3389 is open, is frequently the target of repeated brute-force hack attempts against this account name.  Options include disabling the Administrator account completely and setup a separate account that has administrator rights, or removing RDP access from the Administrator account.  Make sure you have a different account with admin rights available before disabling the Administrator account so you don’t get locked out.  Generally it is better to disable the Administrator account (and replace with a different account with administration rights) rather than just renaming the Administrator account because the SID remains 500 when you rename it and there are some non-Microsoft tools that allow authentication by using SID rather than account name (but renaming is still better than doing nothing….you can rename the  Administrator account in Local Security Policy (Security Settings, Local Policies, Security Options, Accounts: Rename administrator account) or via gpedit.msc).   We noted on a test server with port 3389 open that over 50% of the failed login attempts were using the “administrator” user name, followed by admin, user, test, user1, etc.

Whitelist IPs: Use Windows Firewall to restrict RDP access to specific IPs only

Whitelist IPs: Use Windows Firewall to restrict RDP access to specific IPs only

If you always connect from the same IP address, or IP address range (or the range your ISP uses), you can restrict RDP access to those IPs through the Windows Firewall (Inbound Rules for Remote Desktop which may consist of multiple rules, TCP-in and UDP-in, and Remote Desktop-User Mode and Remote Desktop Services-User Mode).  Go to the scope tab of the inbound firewall rule and add your IP addresses to the Remote IP list for both rules.  This is a great method to secure RDP when always working from the same location but it won’t work if you plan to access your Remote Desktop Server while traveling because you won’t be using the same static IP address.

Always use complex usernames and passwords for user accounts

Utilize complex usernames/passwords

It’s very important to use mix of special characters, numbers, upper & lower case letters, non-words and require longer length.  Don’t use standard usernames such as administrator, user, user1, test, admin, etc.  Avoid creating passwords that include your name, dictionary words or reusing passwords from other accounts.  You may want to increase the default minimum length beyond 6 characters.  Using simple passwords is the easiest way for someone to compromise your server – do NOT use simple passwords that are vulnerable to brute-force and dictionary attacks.

You can enforce strong/complex passwords and policies at Local Security Policy, Security Settings, Account Policies, Password Policy, see policies including “password must meet complexity requirements”  (or this can be done via gpedit.msc, Computer Configuration -> Windows Settings -> Security Settings -> Account Policies -> Password Policy) – the password complexity policy should be enabled by default on Windows Server 2016 but you should verify and adjust policies if needed (such as keeping password complexity enabled but increase the password length policy to a higher number of characters).  After changing policies, you should always test your changes.

Also, please note that the “user much change password at next logon” selection box in user properties does not work with RDP sessions.  A workaround is to have users manually change their password upon logon by pressing control-alt-end and following the change password prompts within a desktop session.

See following links for additional info:

https://technet.microsoft.com/en-us/library/hh994562(v=ws.11).aspx

https://docs.microsoft.com/en-us/windows/device-security/security-policy-settings/password-must-meet-complexity-requirements

Make sure to keep this policy Disabled, “Store password using reversible encryption”, as described here:  https://technet.microsoft.com/en-us/library/hh994559%28v=ws.11%29.aspx?f=255&MSPPError=-2147217396

Windows 2016 Remote Desktop Server RDS doesn’t allow change password at next logon

We have seen several users have this issue where they cannot login if the checkbox in user properties for “user much change password at next logon” has been enabled.  Various comments and posts online indicate that changes in the windows authentication process in recent OS versions don’t allow expired users to change their password via RDP once it expires when Network Level Authentication or Credential Security Support Provider (CredSSP) is enabled.  This is only an issue trying to force users to change their password on a RDP session – it works fine from a console session if you are local to the machine.

Try to un-check this box by “user must change password at next logon” if it is currently checked. Remember to always create complex, strong passwords!

Users can manually change their password upon logon by pressing control-alt-end and following the change password prompts).

Advantages to using Riptide Hosting SPLA Microsoft Licenses

Advantages to using Riptide Hosting SPLA Microsoft Licenses

Most customers use our Microsoft licensing (Windows Server, Office, SQL Server, Remote Desktop Services – RDS) provided under the SPLA program (Service Provider Licensing Agreement) on a monthly basis rather than purchasing their own MS Volume Licenses.  (Windows Server CAL licenses are not required with our SPLA licensing which are required under regular MS Volume Licensing).

Using our Microsoft SPLA licensing eliminates upfront fees and makes it easy to increase and decrease licenses each month.

If you own Microsoft Volume Licenses, you can use our Dedicated Hardware Server offering and transfer your own licenses but depending on which licenses you own and how many users you have, it may still be cheaper to utilize our virtual servers/VMs with our SPLA licenses.  Contact us to review options and pricing.  We discuss the advantages to using SPLA licenses below.

SPLA LICENSES — Advantages to using our MS Licensing under SPLA:

  • Pay monthly with no commitment (versus Volume Licenses which may be 1-3 year term)
  • Pay for exactly the number of licenses you need today, not more (for user based licensing (i.e. RDS SALs/user licenses, Office SALs), we can increase the number of licenses easily so you can only license what is needed)
  • For Windows Server under SPLA, no additional Windows Server CALs are needed (you still need RDS SALs if applicable).
  • Upgrade rights (similar to software assurance) are included– You can upgrade to the latest version.
  • No large upfront payment like if you purchase perpetual MS Volume Licenses.
  • No minimum purchase – Can increase user licenses in increments of one user. (Some volume licensing programs have a minimum purchase or minimum points)
  • You cannot install or use your own licenses for SQL Server, RDS, Office or Office 365 on our Virtual Servers due to Microsoft licensing restrictions.
  • Example Pricing:
    • Windows Server licensing is included in our base server cost
    • RDS user licenses are $8.99 per user per month
    • SQL Server Standard is $316/mo per 4 cores versus retail pricing of approx. $7,500 per 4 cores plus add Software Assurance annually.

VOLUME LICENSES — Advantages to using/purchasing your own Volume Licensing

  • If measuring over a long-term period, perpetual volume license may cost less than monthly SPLA license (but you have a long-term agreement with large upfront fee, plus you have to purchase Software Assurance separately, as well as Windows CALs on top of Windows Server).
    **If you end up needing fewer licenses you will still pay for all the licenses you purchased.
  • SQL Server Standard and Enterprise can be very expensive (often times as much as the underlying server cost!) and if you have already purchased these licenses you may want to use them to save money, although you are required to use our Dedicated Hardware Server hosting to use your own licensing.
  • If you have a large number of users and already have your own Office licensing (or Office 365 plan that will work on a server or terminal server), then you may want to use them to save money, although you are required to use our Dedicated Hardware Server hosting to use your own licensing.

VIRTUAL SERVER HOSTING — Virtual Server Environment at Riptide Hosting:

  • SPLA licenses only. You must license SQL Server, RDS and Office through us (SPLA) in our VM environment.  You cannot use your own licensing of SQL Server, RDS, Office, or Office 365 on our VMs.
  • Lower entry costs, VMs start at $100/month
  • Best for VMs with fewer resources (less than 25 users, less than 200 GB space, less than 8g RAM and 4vCPU)
  • Less expensive full image backup options with quick restores
  • May be less expensive to use our SPLA licenses on a VM with full image backup, even in scenarios where you have your own licensing.

DEDICATED SERVER HOSTING — Dedicated Hardware Server Environment at Riptide Hosting:

  • You can use our SPLA licenses or use your own Volume Licenses. Where the server hardware is fully dedicated to you, the outsourcing language within Microsoft Product Terms applies.
  • Best when you need significant resources (greater than 25 users, more than 200 GB disk space, more than 8g RAM and 4vCPU).
  • Our Dedicated Servers start around $300/month. Compare this to AWS Dedicated Instances or AWS Dedicated Hosts that start at over $1k per month and you have to bring all your own licensing.
  • Requires more expensive full server image backup options due to much higher disk space provided.
  • Only hosting offering we provide that allows you to use your own SQL Server, RDS, Office, or Office 365 licenses. Even if you have your own licensing, make sure it can be use on a remote hosted server.  For example, Office 365 Business Plans won’t work on a Windows Server with Remote Desktop Services because Office 365 Business doesn’t include Pro Plus.

RDS — Remote Desktop Services (RDS) Licensing Notes:

  • We get asked a lot of questions about RDS licenses and here are some of our most common discussions.
  • Many hosting providers don’t even offer the ability to license RDS SALs through them and require you to have your own licenses. If you are using Remote Desktop Services (RDS), make sure you understand whether your hosting provider can provide the required licenses or not.  **If you can only login with two accounts then they did not provide you licensing for RDS access other than for maintenance.
  • The RDS CALs/SALs are not part of the Windows Server OS licensing and are applied separately. Riptide Hosting provides RDS SALs on a monthly basis (with no long-term commitment) at $8.99 per user. For example, AWS doesn’t offer RDS user licensing.  You have to buy them from MS and then bring them to AWS via License Mobility which requires that you maintain active Software Assurance on the RDS CALs and go through a MS license verification process.
  • Microsoft only provides RDS user licenses on a per-unique-end-user basis. There is no concurrent licensing model available from Microsoft for RDS.  All users, regardless of actual usage, require a license. 

Windows Server and SQL Server Licensing Notes:

  • SQL Server is licensed per core but with a minimum of 4 cores per VM or per processor.
  • Windows Server is also now licensed per core (starting with Windows Server 2016)
  • SQL Server comes in multiple editions: Express (free), Web (through SPLA only; for publicly accessible web pages, etc.), Standard, Enterprise. Contact us for differences and monthly SPLA pricing.