Solved

Requirements for (Perfect) Forward Secrecy on Exchange 2010?

Posted on 2014-10-08
3
1,355 Views
Last Modified: 2014-10-20
One of our customers is required to use Perfect Forward Secrecy for his mail server.

What are the requirements to use PFS on SBS2011(based on 2008R2)/Exchange for SMTP?

OWA/Outlook Anywhere/Acitve Sync are not the priority, but it would be nice to cover that too. At least it shouldn't break these features.

Do they need a certificate from a public CA or is a private CA enough? Are there special requirements the certificate has to meet?

What changes are needed in SBS2011 and/or Exchange and/or IIS to use Perfect Forward Secrecy for SMTP?
0
Comment
Question by:exexc
  • 2
3 Comments
 
LVL 80

Accepted Solution

by:
David Johnson, CD, MVP earned 500 total points
ID: 40368102
the changes are in SSL settings where you have to set the cipher suites
here is a powershell script to do it for you:
# Copyright 2014, Alexander Hass
# http://www.hass.de/content/setup-your-iis-ssl-perfect-forward-secrecy-and-tls-12
 
# Add and Enable SSL 3.0 for client and server SCHANNEL communications
md 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\SSL 3.0' -Force
md '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' -name 'Enabled' -value '0xffffffff' -PropertyType 'DWord' -Force
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\SSL 3.0\Server' -name 'DisabledByDefault' -value 0 -PropertyType 'DWord' -Force
 
# Add and Enable TLS 1.0 for client and server SCHANNEL communications
md 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.0' -Force
md 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.0\Server' -Force
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.0\Server' -name 'Enabled' -value '0xffffffff' -PropertyType 'DWord' -Force
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.0\Server' -name 'DisabledByDefault' -value 0 -PropertyType 'DWord' -Force
 
# Add and Enable TLS 1.1 for client and server SCHANNEL communications
md 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.1' -Force
md 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.1\Server' -Force
md 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.1\Client' -Force
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.1\Server' -name 'Enabled' -value '0xffffffff' -PropertyType 'DWord' -Force
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.1\Server' -name 'DisabledByDefault' -value 0 -PropertyType 'DWord' -Force
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.1\Client' -name 'Enabled' -value 1 -PropertyType 'DWord' -Force
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.1\Client' -name 'DisabledByDefault' -value 0 -PropertyType 'DWord' -Force
 
# Add and Enable TLS 1.2 for client and server SCHANNEL communications
md 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2' -Force
md 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Server' -Force
md 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Client' -Force
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Server' -name 'Enabled' -value '0xffffffff' -PropertyType 'DWord' -Force
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Server' -name 'DisabledByDefault' -value 0 -PropertyType 'DWord' -Force
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Client' -name 'Enabled' -value 1 -PropertyType 'DWord' -Force
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Client' -name 'DisabledByDefault' -value 0 -PropertyType 'DWord' -Force
 
# Disable Multi-Protocol Unified Hello
md 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\Multi-Protocol Unified Hello\Server' -Force
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\Multi-Protocol Unified Hello\Server' -name Enabled -value 0 -PropertyType 'DWord' -Force
 
# Disable PCT 1.0
md 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\PCT 1.0' -Force
md 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\PCT 1.0\Server' -Force
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\PCT 1.0\Server' -name Enabled -value 0 -PropertyType 'DWord' -Force
 
# Disable SSL 2.0 (PCI Compliance)
md 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\SSL 2.0\Server' -Force
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\SSL 2.0\Server' -name Enabled -value 0 -PropertyType 'DWord' -Force
 
# WARNING: If you disable SSL 3.0 the you may lock out some people still using
# Windows XP with IE6/7. Without SSL 3.0 enabled, there is no protocol available
# for these people to fall back. Safer shopping certifications may require that
# you disable SSLv3. I suspect in mid 2015 this can safely disabled.
#
# Disable SSL 3.0 (PCI Compliance)
#md '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' -name Enabled -value 0 -PropertyType 'DWord' -Force
 
# Disable insecure ciphers
$insecureCiphers = 'NULL','RC2 40/128','RC2 56/128','RC2 128/128','RC4 40/128','RC4 56/128','RC4 64/128','DES 56/56'
Foreach ($insecureCipher in $insecureCiphers) {
  $key = (Get-Item HKLM:\).OpenSubKey('SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers', $true).CreateSubKey($insecureCipher)
  $key.SetValue('Enabled', 0, 'DWord')
  $key.close()
  Write-Host "$insecureCipher has been disabled"
}
 
# Enable new secure ciphers
$secureCiphers = 'RC4 128/128','Triple DES 168/168','AES 128/128','AES 256/256'
Foreach ($secureCipher in $secureCiphers) {
  $key = (Get-Item HKLM:\).OpenSubKey('SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers', $true).CreateSubKey($secureCipher)
  New-ItemProperty -path "HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers\$secureCipher" -name 'Enabled' -value '0xffffffff' -PropertyType 'DWord' -Force
  $key.close()
  Write-Host "$secureCipher has been enabled"
}
 
# Set hashes configuration
md 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Hashes\MD5' -Force
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Hashes\MD5' -name Enabled -value '0xffffffff' -PropertyType 'DWord' -Force
 
md 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Hashes\SHA' -Force
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Hashes\SHA' -name Enabled -value '0xffffffff' -PropertyType 'DWord' -Force
 
# Set KeyExchangeAlgorithms configuration
md 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\KeyExchangeAlgorithms\Diffie-Hellman' -Force
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\KeyExchangeAlgorithms\Diffie-Hellman' -name Enabled -value '0xffffffff' -PropertyType 'DWord' -Force
 
md 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\KeyExchangeAlgorithms\PKCS' -Force
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\KeyExchangeAlgorithms\PKCS' -name Enabled -value '0xffffffff' -PropertyType 'DWord' -Force
 
# Set cipher suites order as secure as possible (Enables Perfect Forward Secrecy)
New-ItemProperty -path 'HKLM:\SOFTWARE\Policies\Microsoft\Cryptography\Configuration\SSL\00010002' -name 'Functions' -value 'TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P521,TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P384,TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P256,TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA_P521,TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA_P384,TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA_P256,TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P521,TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA_P521,TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P384,TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256,TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA_P384,TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA_P256,TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384_P521,TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384_P384,TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256_P521,TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256_P384,TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256_P256,TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384_P521,TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384_P384,TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA_P521,TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA_P384,TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA_P256,TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256_P521,TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256_P384,TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256_P256,TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA_P521,TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA_P384,TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA_P256,TLS_DHE_DSS_WITH_AES_256_CBC_SHA256,TLS_DHE_DSS_WITH_AES_256_CBC_SHA,TLS_DHE_DSS_WITH_AES_128_CBC_SHA256,TLS_DHE_DSS_WITH_AES_128_CBC_SHA,TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA,TLS_RSA_WITH_AES_256_CBC_SHA256,TLS_RSA_WITH_AES_256_CBC_SHA,TLS_RSA_WITH_AES_128_CBC_SHA256,TLS_RSA_WITH_AES_128_CBC_SHA,TLS_RSA_WITH_RC4_128_SHA,TLS_RSA_WITH_3DES_EDE_CBC_SHA' -PropertyType 'String' -Force
 
 
Write-Host 'After the system has been rebooted you can verify your server configuration at https://www.ssllabs.com/ssltest/'
Write-Host -ForegroundColor Red 'A computer restart is required to apply settings. Restart computer now?'
Restart-Computer -Force -Confirm

Open in new window

0
 

Author Comment

by:exexc
ID: 40368155
Thank you for the script.

I have some more questions before I try that in a productive system:

Will these changes have a negative effect or require additional changes to IIS/OWA/Active Sync/Outlook Anywhere?

Is there a way to check the results for SMTP connections? I found a solution using Linux/openssh to check the ciphers - is there any way to do it with Windows? The test from ssllabs.com is for HTTPS only and the test from ssl-tools.net says that PFS is already available (before I made any changes).

Are there any requirements regarding the certificate? Is the SHA1/RSA certificate we created with an internal CA good enough?
0
 

Author Closing Comment

by:exexc
ID: 40391488
After some more research I was able to successfully change the SSL settings. Everything is still working.

Thank you for the solution.
0

Featured Post

Free Tool: ZipGrep

ZipGrep is a utility that can list and search zip (.war, .ear, .jar, etc) archives for text patterns, without the need to extract the archive's contents.

One of a set of tools we're offering as a way to say thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

When you’re making plans to join the modern business race, you should analyze various details that may affect your results. Nowadays, millions of businesses are trying to grow into established and appreciated professional enterprises.
In-place Upgrading Dirsync to Azure AD Connect
In this Micro Video tutorial you will learn the basics about Database Availability Groups and How to configure one using a live Exchange Server Environment. The video tutorial explains the basics of the Exchange server Database Availability grou…
A short tutorial showing how to set up an email signature in Outlook on the Web (previously known as OWA). For free email signatures designs, visit https://www.mail-signatures.com/articles/signature-templates/?sts=6651 If you want to manage em…

685 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question