This policy setting determines whether RC4 stream cipher is disabled. The RC4 algorithm, as used in the TLS protocol and SSL protocol, has many single-byte biases, which makes it easier for remote attackers to conduct plaintext-recovery attacks via statistical analysis of ciphertext in a large number of sessions that use the same plaintext. Countermeasure: Configure this setting to disable RC4. Potential Impact: Windows clients that have these registry entries set won't be able to connect to sites that require RC4. Windows servers that have these registry entries set won't be able to service clients that must use RC4. Fix: (1) REG: HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlSecurityProvidersSCHANNELCiphersRC4 128/128!Enabled HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlSecurityProvidersSCHANNELCiphersRC4 40/128!Enabled HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlSecurityProvidersSCHANNELCiphersRC4 56/128!Enabled

[disabled/enabled]

REG: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers\RC4 128/128!Enabled HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers\RC4 40/128!Enabled HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Ciphers\RC4 56/128!Enabled