Do you want to reach the heights of having an A graded server on SSLABS server tests? 

First thing you need to do on a fresh install of Windows server 2012 R2 and IIS 8.5 is disable SSL3 functionality, this can be achieved by following this guide. Come back here once you have done this. Or if you trust me here’s my exported regedit key, which you can just import to your server.

Below is the Cipher Key string that I put into the Local Group Policy Editor. To do so click the Windows icon and type in gpedit.msc and press enter to launch the Policy Editor.  Open on the left the folder titled ‘Administrative Templates‘ / ‘Network’  / ‘SSL Configuration Settings’ & double click on ‘SSL Cipher Suite Order‘ to open. Now Enable the SSL Cipher Suites and copy and paste the below list in. Click OK and restart your server, now run the SSL server test again to see the result.

TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P256,
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P384,
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256,
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P384,
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA_P256,
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA_P384,
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA_P256,
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA_P384,
TLS_RSA_WITH_AES_256_GCM_SHA384,
TLS_RSA_WITH_AES_128_GCM_SHA256,
TLS_RSA_WITH_AES_256_CBC_SHA256,
TLS_RSA_WITH_AES_128_CBC_SHA256,
TLS_RSA_WITH_AES_256_CBC_SHA,
TLS_RSA_WITH_AES_128_CBC_SHA,
TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384_P384,
TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256_P256,
TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256_P384,
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384_P384,
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256_P256,
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256_P384,
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA_P256,
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA_P384,
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA_P256,
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA_P384,
TLS_DHE_DSS_WITH_AES_256_CBC_SHA256

Cipher suite from above all on one line for copying into GPEDIT.MSC

TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P256,TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P384,TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256,TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P384,TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA_P256,TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA_P384,TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA_P256,TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA_P384,TLS_RSA_WITH_AES_256_GCM_SHA384,TLS_RSA_WITH_AES_128_GCM_SHA256,TLS_RSA_WITH_AES_256_CBC_SHA256,TLS_RSA_WITH_AES_128_CBC_SHA256,TLS_RSA_WITH_AES_256_CBC_SHA,TLS_RSA_WITH_AES_128_CBC_SHA,TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384_P384,TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256_P256,TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256_P384,TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384_P384,TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256_P256,TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256_P384,TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA_P256,TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA_P384,TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA_P256,TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA_P384,TLS_DHE_DSS_WITH_AES_256_CBC_SHA256

The following 2 Cipher’s currently only work on Windows server 2016 & IIS 10

TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384

*Note: I’ve included ‘TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256‘ & ‘TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384‘ in a separate code block below the main cipher keys, although these do not currently work on Windows 2012 with IIS 8.5 – I’m hoping that a patch with come through from Microsoft soon which enables them, as these will take the ‘A’ to an ‘A+’ rating, as they do when using Windows Server 2016 IIS 10.

So if you are using IIS 10 on Windows Server 2016 then add these to the top and removed the bottom two as all keys will not fit within the cipher field.