Go Premium for a chance to win a PS4. Enter to Win

x
  • Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 1466
  • Last Modified:

Requirements for (Perfect) Forward Secrecy on Exchange 2010?

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
exexc
Asked:
exexc
  • 2
1 Solution
 
David Johnson, CD, MVPOwnerCommented:
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
 
exexcAuthor Commented:
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
 
exexcAuthor Commented:
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

Problems using Powershell and Active Directory?

Managing Active Directory does not always have to be complicated.  If you are spending more time trying instead of doing, then it's time to look at something else. For nearly 20 years, AD admins around the world have used one tool for day-to-day AD management: Hyena. Discover why

  • 2
Tackle projects and never again get stuck behind a technical roadblock.
Join Now