Information
The RC4 Cipher Suites are considered insecure, therefore should be disabled.
Note: RC4 cipher enabled by default on Server 2012 and 2012 R2 is RC4 128/128.
Rationale:
The use of RC4 may increase an adversaries ability to read sensitive information sent over SSL/TLS.
Impact:
The RC4 Cipher Suites will not be available. The use of RC4 in TLS and SSL could allow an attacker to perform man-in-the-middle attacks and recover plaintext from encrypted sessions.
Solution
Perform the following to disable RC4 40/128, RC4 56/128, RC4 64/128, RC4 128/128 ciphers:
Set the following Registry keys to 0.
HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers\RC4 40/128:Enabled
HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers\RC4 56/128:Enabled
HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers\RC4 64/128:Enabled
HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers\RC4 128/128:Enabled
To disable using PowerShell enter the following commands:
(Get-Item 'HKLM:\').OpenSubKey('SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers', $true).CreateSubKey('RC4 40/128')
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers\RC4 40/128' -name 'Enabled' -value '0' -PropertyType 'DWord' -Force | Out-Null
(Get-Item 'HKLM:\').OpenSubKey('SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers', $true).CreateSubKey('RC4 56/128')
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers\RC4 56/128' -name 'Enabled' -value '0' -PropertyType 'DWord' -Force | Out-Null
(Get-Item 'HKLM:\').OpenSubKey('SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers', $true).CreateSubKey('RC4 64/128')
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers\RC4 64/128' -name 'Enabled' -value '0' -PropertyType 'DWord' -Force | Out-Null
(Get-Item 'HKLM:\').OpenSubKey('SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers', $true).CreateSubKey('RC4 128/128')
New-ItemProperty -path 'HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers\RC4 128/128' -name 'Enabled' -value '0' -PropertyType 'DWord' -Force | Out-Null