Publish DirectAccess with Forefront TMG 2010

January 26, 2015 Comments off

DirectAccess is a compelling remote access solution that provides seamless and transparent, always-on, bi-directional remote corporate network connectivity for managed Windows clients. In Windows Server 2008 R2 and Forefront Unified Access Gateway (UAG) 2010, the DirectAccess server had to be configured with two network adapters, with the external network interface configured with two consecutive public IPv4 addresses. Many security engineers were understandably concerned about exposing a domain-joined Windows server directly to the public Internet, which limited the adoption of the technology. Beginning with Windows Server 2012, DirectAccess is integrated in to the operating system and provides more flexible network configuration. DirectAccess can now be deployed behind an existing edge security solution performing NAT, and even supports single-NIC configuration.

The Forefront TMG 2010 firewall is an excellent choice to provide essential protection for the DirectAccess workload. When DirectAccess is deployed behind a NAT device, the only firewall port that needs to be opened is TCP port 443 (HTTPS).

When publishing DirectAccess with TMG, it is important to use a server publishing rule and not a web publishing rule. To publish DirectAccess, open the Forefront TMG 2010 management console, right-click Firewall Policy in the navigation tree, and then choose New Non-Web Server Publishing Rule.

Publish DirectAccess with Forefront TMG 2010

Provide a descriptive name for the rule, enter the IP address of the DirectAccess server, choose HTTPS Server for the protocol, and then select the network interface on which to listen for these requests.

Publish DirectAccess with Forefront TMG 2010

To ensure the proper operation of Receive Side Scaling (RSS) on the DirectAccess server, it is recommended that the server be configured to use TMG as its default gateway and to configure the publishing rule on TMG using the option Requests appear to come from the original client.

Publish DirectAccess with Forefront TMG 2010

Also, TMG does not support load balancing for server publishing rules, so it is not possible to deliver traffic to multiple back end servers using TMG. For high availability and to provide for scalability, it is recommended to configure load balancing for DirectAccess using NLB or an external load balancer (recommended) and publish the virtual IP address (VIP) using the steps described above.

To learn more about DirectAccess, visit http://directaccess.richardhicks.com/

Forefront TMG 2010 SQL Services Fail to Start After Disabling SSL 3.0

November 20, 2014 5 comments

When performing POODLE attack mitigation on the Forefront TMG 2010 firewall by disabling SSL 3.0, you may encounter a scenario in which TMG’s SQL services fail to start after a reboot.

Forefront TMG 2010 SQL Services Fail to Start After Disabling SSL 3.0

Looking through the Windows system event log you may see an error message logged by the Service Control Manager with event ID 36871 which states:

A fatal error occurred while creating an SSL server credential.
The internal error state is 10013.

Forefront TMG 2010 SQL Services Fail to Start After Disabling SSL 3.0

In addition you may also see an error message logged by the Service Control Manager with event ID 7024 which states:

The SQL Server (ISARS) service terminated with service-specific
error %%-2146893007.

Forefront TMG 2010 SQL Services Fail to Start After Disabling SSL 3.0

This can occur when SSL 3.0 is disabled at the same time that TLS 1.0 is also disabled. Even though TLS 1.1 and 1.2 might be enabled, TMG requires that TLS 1.0 specifically be enabled for SQL server services to function properly when SSL 3.0 is disabled.

To resolve this issue, enable TLS 1.0 Server in the registry by changing the value of Enabled to 1, as shown here. If these registry keys do not exist, create them.

Forefront TMG 2010 SQL Services Fail to Start After Disabling SSL 3.0

Restart the server for the change to take effect.

Mitigating the POODLE SSL 3 Vulnerability on Forefront TMG 2010

October 21, 2014 20 comments

Recently a new and very serious vulnerability in the SSL 3.0 protocol has been discovered that allows an attacker to recover sensitive information for an encrypted session. The Qualys SSL Labs server test has been updated to identify and warn about this issue.

Mitigating the POODLE SSL 3.0 Vulnerability on Forefront TMG 2010

Figure 1 – Qualys SSL Labs Server Test Score for TMG Published Secure Web Site

On a Forefront TMG server with SSL hardening implemented as I’ve outlined here and here, the POODLE attack is mitigated, but it is still recommended that you disable SSL 3.0 altogether. SSL 3.0 is an old, outdated protocol that is no longer widely used, and disabling it should have minimal impact on clients connecting to secure web sites published by the Forefront TMG 2010 firewall.

To disable SSL 3.0 on the TMG firewall, open an elevated PowerShell window and execute the following commands:

New-Item -Path “HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\SSL 3.0\Server” -Force

New-ItemProperty -Path “HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\SSL 3.0\Server” -PropertyType dword -Value 0 -Name Enabled

Note: Use caution when copying/pasting the above commands as wrapping of the text has occurred.

A restart of the server is required for the change to take effect.

Forefront TMG 2010 Network Inspection System NIS Signature Updates

September 15, 2014 2 comments

When Microsoft announced the formal end-of-life for Forefront TMG 2010, they laid out in clear detail the support boundaries for the product going forward. Microsoft stated specifically that they would continue mainstream support for TMG until April of 2015, and extended support would terminate in April 2020. However, the Web Protection Service (WPS) updates for the URL filtering database, antimalware signatures, and the Network Inspection System (NIS) would only continue until December 31, 2015.

Unfortunately, it appears that Microsoft has abandoned the updating for NIS signatures. You may have noticed that a fully updated Forefront TMG firewall with the latest signature updates shows that the last NIS signature was released for security bulletin MS12-050 on July 20, 2012!

Forefront TMG 2010 Network Inspection System (NIS) Signature Updates

Forefront TMG 2010 Network Inspection System (NIS) Signature Updates

I find it difficult to believe that there hasn’t been a single vulnerability discovered or hotfix released since July of 2012 that wouldn’t benefit from NIS protection, so I have to assume that Microsoft is no longer supporting NIS in spite of their pledge to provide support for WPS through the end of 2015. If you are relying on NIS for essential network protection, it’s time to consider deploying a dedicated IDS/IPS solution or another solution that provides this functionality.

Recommended Forefront TMG 2010 SSL and TLS Configuration

September 8, 2014 6 comments

Last year I wrote an article for ISAserver.org that provided detailed guidance for improving security for SSL and TLS protected web sites using Forefront TMG 2010. Many people have reached out to me recently to ask about enabling forward secrecy, which my original article did not include because, at the time, it was not recommended to enable it. However, as times have changed, it is now recommended to enable forward secrecy so I recently wrote a short post with guidance on how to do that. The post was written with a very narrow scope and addressed only the enabling of forward secrecy for TLS. Many of you have since asked for guidance on overall security best practices with regard to SSL and TLS along with adding support for forward secrecy. In addition to the configuration changes detailed in my original ISAserver.org article, I also recommend the following list of SSL and TLS cipher suites be explicitly enforced using the method outlined here.

TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256_P256
TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256_P384
TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256_P521
TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384_P384
TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384_P521
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256_P256
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA_P256
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA_P256
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P256
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA_P256
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA_P256
TLS_DHE_DSS_WITH_AES_128_CBC_SHA256
TLS_DHE_DSS_WITH_AES_256_CBC_SHA256
TLS_DHE_DSS_WITH_AES_128_CBC_SHA
TLS_DHE_DSS_WITH_AES_256_CBC_SHA
TLS_RSA_WITH_AES_128_CBC_SHA256
TLS_RSA_WITH_AES_256_CBC_SHA256
TLS_RSA_WITH_AES_128_CBC_SHA
TLS_RSA_WITH_AES_256_CBC_SHA

Using this configuration, the Forefront TMG 2010 firewall should receive an A rating from the SSL Labs test site (at the time of this writing).

Forefront TMG 2010 SSL Security Configuration

Enabling and supporting the above list of cipher suites will provide the best overall protection and performance for your SSL protected web sites. Note that the list above does not include support for SSL 3.0. If you need to support SSL 3.0 you should add the following cipher suites to the end of the list.

TLS_RSA_WITH_RC4_128_SHA
TLS_RSA_WITH_RC4_128_MD5

Please note that this configuration may not work with older browsers on old, unsupported operating systems, for example Internet Explorer 6 on Windows XP. Before deploying this configuration in production I would encourage you to conduct some testing with your supported clients to ensure operability.

Enable TLS Forward Secrecy for Forefront TMG 2010 Published Web Sites

August 28, 2014 3 comments

Last year I wrote an article for ISAserver.org that outlined in detail how to improve SSL and TLS security for web sites published using Forefront TMG 2010. In its default configuration, Windows Server 2008 R2 and Forefront TMG leave quite a bit to be desired in terms of SSL and TLS security. In the article I demonstrated how to dramatically improve the security posture of TMG when publishing web sites that use SSL and TLS. At the time I wrote the article it was not recommended to enable forward secrecy, so the changes I originally proposed resulted in an “A” score from the Qualys SSL Labs test site. However, times have changed since then, and with the recent revelations of wide spread government spying, it is now recommended to enable forward secrecy by default. Sites that don’t support forward secrecy will now receive a reduced grade.

Enable TLS Forward Secrecy for Forefront TMG 2010 Published Web Sites

To accomplish this on the Forefront TMG 2010 firewall, open the Local Group Policy Editor (gpedit.msc) and navigate to Computer Configuration, Administrative Templates, Network, SSL Configuration Settings. Double-click SSL Cipher Suite Order and choose Enabled. Copy the list of SSL cipher suites to a blank notepad document and then move all of the cipher suites that begin with TLS_ECDHE_RSA_WITH_AES_ to the front of the list. Use caution here because the list cannot have any extra commas, line breaks, or spaces at all. Paste the updated list back in to the SSL Cipher Suites box and click Ok.

Enable TLS Forward Secrecy for Forefront TMG 2010 Published Web Sites

The server will have to be restarted for the changes to take effect. Once complete, forward secrecy will now be used by modern browsers and you should once again receive an “A” grade from SSL Labs.

Enable TLS Forward Secrecy for Forefront TMG 2010 Published Web Sites

Hotfix Rollup 5 for Forefront TMG 2010 SP2 Now Available

Hotfix rollup 5 for Microsoft Forefront TMG 2010 with Service pack 2 (SP2) is now available for download. This latest hotfix rollup includes fixes for the following issues:

KB2963805 – Account lockout alerts are not logged after you install Rollup 4 for Forefront TMG 2010 SP2

KB2963811 – The Forefront TMG 2010 Firewall service (wspsrv.exe) may crash when the DiffServ filter is enabled

KB2963823 – “1413 Invalid Index” after you enable cookie sharing across array members in Forefront TMG 2010

KB2963834 – HTTPS traffic may not be inspected when a user accesses a site through Forefront TMG 2010

KB2967726 – New connections are not accepted on a specific web proxy or web listener in Forefront TMG 2010

KB2965004 – EnableSharedCookie option doesn’t work if the Forefront TMG 2010 service runs under a specific account

KB2932469 – An incorrect value is used for IPsec Main Mode key lifetime in Threat Management Gateway 2010

KB2966284 – A zero value is always returned when an average counter of the “Forefront TMG Web Proxy” object is queried from the .NET Framework

KB2967763 – The “Const SE_VPS_VALUE = 2” setting does not work for users if the UPN is not associated with a real domain

KB2973749 – HTTP Connectivity Verifiers return unexpected failures in TMG 2010

You can download hotfix rollup 5 for Forefront TMG 2010 SP2 here. After applying this update, the new Forefront TMG 2010 build number will be 7.0.9193.644.

Forefront TMG 2010 Computer Certificate Request or Renewal Fails

April 21, 2014 2 comments

When attempting to request or renew a computer certificate on the Forefront TMG 2010 firewall, you may receive the following error message:

Status: Failed
The RPC server is unavailable.

 

forefront_tmg_2010_certificate_01

This occurs because the Forefront TMG 2010 firewall does not, by default, allow the protocols and ports required to request or renew a certificate from a Certificate Authority (CA). Common workarounds suggest stopping the firewall completely or creating a rule allowing all protocols and ports from the TMG firewall to the CA. However, both of these workarounds are problematic. Stopping the firewall is a manual process that will cause a service disruption. It also leaves the firewall in an unprotected state. For edge deployment scenarios, the underlying operating system will be exposed directly to untrusted networks, which is a serious security risk. Creating an open access rule is not desirable because it violates the basic security principle of least privilege by allowing more access than is required.

To properly address this issue and allow for the secure request and renewal of certificates without disruption and with the least exposure, it will be necessary to create an access rule on the Forefront TMG 2010 firewall to allow all dynamic ports (TCP 49152-65535) from the local host network to the IP address of the CA for all users.

forefront_tmg_2010_certificate_02

Note: Allowing all dynamic ports (TCP 49152-65535) might also be considered too much access from the Forefront TMG 2010 firewall to the CA. It is possible to restrict the dynamic ports used by TMG and further tighten the access rule, if required. For information about restricting dynamic ports, click here.

In addition to the access rule allowing all dynamic ports, it will also be necessary to make a change to a system policy rule. To do this, right-click the Firewall Policy node in the navigation tree and choose All Tasks, System Policy, and then Edit System Policy. In the Authentication Services group highlight Active Directory and clear the checkbox next to Enforce strict RPC compliance.

forefront_tmg_2010_certificate_03

Once these changes have been made you can now request or renew a computer certificate on the Forefront TMG 2010 firewall successfully.

forefront_tmg_2010_certificate_04

Forefront UAG 2010 End of Life Statement

December 17, 2013 4 comments

Today, Microsoft announced the end of life for the Forefront UAG 2010 product. Microsoft will continue to provide mainstream support for UAG until April 14, 2015, and extended support until April 14, 2020. Existing customers with active Software Assurance on their existing UAG licenses as of December 1, 2013, may add new UAG server instances, users, and devices without having to purchase additional UAG licenses. In addition, existing customers who have purchased Forefront UAG server licenses will be given upgrade rights to Windows Server 2012 R2, which provides some of the remote access features found in Forefront UAG. For example, Windows Server 2012 R2 supports DirectAccess, client-based VPN, and reverse web proxy with new Web Application Proxy role.

With regard to license upgrade rights, users are entitled to a Windows Server 2012 R2 license for each Forefront UAG server license (or External Connector license) they currently own. Software Assurance for UAG can still be purchased until January 1, 2014. Forefront UAG 2010 will be removed from the pricelist on July 1, 2014. Forefront UAG 2010 will continue to be available from Microsoft OEM hardware partners like Celestix Networks for the foreseeable future, however.

Forefront UAG Service Pack 4 Now Available for Download

November 27, 2013 Comments off

Good news! Service Pack 4 (SP4) for Forefront Unified Access Gateway (UAG) 2010 is now available for download. This latest service pack for UAG includes updates to support Windows 8.1 client devices using Internet Explorer 11, the native mail app, and Remote Desktop Connection (RDC) 8.1 client. In addition, SP4 for Forefront UAG 2010 also includes support for publishing RemoteApps from a Remote Desktop Session Host running on Windows Server 2012 or 2012 R2. The service pack also includes fixes for various reported issues.

KB2907776 – The UserMgrCom service crashes intermittently in Forefront UAG 2010

KB2909151 – Trunk authentication fails when the global catalog server is unavailable in Forefront UAG 2010

KB2909168 – The W3wp.exe process randomly stops and causes all sessions to disconnect in Forefront UAG 2010

KB2909182 – “The URL contains an invalid path” error occurs when you try to access an Exchange 2013 OWA website

KB2909191 – You cannot connect to corporate IPv4 resources by using DirectAccess after Forefront UAG 2010 Service Pack 3 is installed

KB2909350 – An SSL VPN application that has the Socket Forwarding mode set to Disabled uses 100 percent of the CPU’s time in Forefront UAG 2010

KB2909353 – You have to authenticate again to the ADFS server when the published server is configured for single sign-on in Forefront UAG 2010

KB2909356 – A detailed HTTP 403.14 error message occurs when you go to a specific InternalSite URL in a Forefront UAG 2010 environment

KB2909365 – A memory leak in W3wp.exe occurs when Outlook Anywhere is published through a Forefront UAG 2010 trunk

KB2909367 – Intermittent HTTP 500 error codes when you access a Forefront UAG 2010 portal

KB2909376 – File uploads do not occur to SharePoint Server 2013 or SkyDrive Pro through Forefront UAG 2010

KB2910407 – An internal 500 error occurs if a custom URL logoff page is configured in Forefront UAG 2010

KB2910413 – Multiple 4625 event IDs are logged when a user logs on in Forefront UAG 2010

KB2910467 – Configuration activation fails on some servers in a large array in Forefront UAG 2010

KB2910498 – A handle leak occurs in Lsass.exe in Forefront UAG 2010

KB2910506 – An authentication prompt is received even though a user is successfully authenticated in Forefront UAG 2010

KB2910517 – An incorrect domain password policy may be used if Active Directory integrated authentication is configured in Forefront UAG 2010

You must have Forefront UAG 2010 SP3 hotfix rollup 1 installed prior to installing SP4. You can download SP3 rollup 1 here. You can download Forefront UAG 2010 SP4 here. Once the update is installed the new Forefront UAG 2010 build number will be 4.0.4083.10000.