Information
RC4 is a stream cipher that has known practical attacks. It is recommended that RC4 be disabled. The only 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.
Solution
To disable RC4 40/128, ensure the following key is absent. If the key is present, ensure it is set to 0.
HKLM\System\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers\RC4 40/128\Enabled
To disable RC4 56/128, ensure the following key is absent. If the key is present, ensure it is set to 0.
HKLM\System\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers\RC4 56/128\Enabled
To disable RC4 64/128, ensure the following key is absent. If the key is present, ensure it is set to 0.
HKLM\System\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers\RC4 64/128\Enabled
To disable RC4 128/128, ensure the following key is set to 0.
HKLM\System\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers\RC4 128/128\Enabled