Nartac Software

IIS Crypto 1.6 has been released. This version adds the 4 additional cipher suites that were updated as part of the MS14-066 (KB2992611) patch. Along with some minor fixes, the PCI template now disables SSL 3.0 and RC4. Full version history can be found here.

Microsoft released a patch named MS14-066 on November 11, 2014 to address a vulnerability in SChannel that could allow remote code execution. The patch includes 4 new cipher suites for Windows Server versions 2003 through 2012 R2. Previously only Windows Server 2012 R2 had these cipher suites. On November 16, Microsoft updated the advisory stating that they found an issue with the new cipher suites they introduced. If you have applied this patch and are running into connection issues with clients, the work around is to disable the following cipher suites: TLS_DHE_RSA_WITH_AES_256_GCM_SHA384, TLS_DHE_RSA_WITH_AES_128_GCM_SHA256, TLS_RSA_WITH_AES_256_GCM_SHA384 and TLS_RSA_WITH_AES_128_GCM_SHA256. Using IIS Crypto simply uncheck these cipher suites, click Apply and reboot your server.

IIS Crypto 1.4 has finally been released. Along with the usual bug fixes, version 1.4 adds in a new Best Practices template which prefers forward secrecy cipher suites with the highest key length. The BEAST template has been removed as RC4 is now considered much weaker than previously was known. A good explaination can be found here. Finally, the SSL scanner from Qualys is now built in so you can scan your website directly from IIS Crypto.

NOTE – This post is outdated. For a full list of registry keys, see our updated FAQ.

Lately, we have been receiving a lot of questions with regards to what exactly IIS Crypto does. I will do my best to answer these questions in this post.

IIS Crypto was created to simplify enabling and disabling various protocols and cipher suites on the many servers we administer. Originally we had a script that we would execute on each server after the initial setup, however, some servers needed different protocols and cipher suites enabled. We also wanted to see the current configuration of existing servers. Thus IIS Crypto was born.

IIS Crypto simply sets a few registry keys to enable/disable protocols, ciphers and hashes as well as reorder cipher suites. Microsoft has an article explaining all of the settings here. These are the exact keys IIS Crypto uses:

HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELProtocolsMulti-Protocol Unified HelloServer
HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELProtocolsPCT 1.0Server
HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELProtocolsSSL 2.0Server
HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELProtocolsSSL 3.0Server
HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELProtocolsTLS 1.0Server
HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELProtocolsTLS 1.1Server
HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELProtocolsTLS 1.2Server

HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELCiphersNULL
HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELCiphersDES 56/56
HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELCiphersRC2 40/128
HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELCiphersRC2 56/128
HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELCiphersRC2 128/128
HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELCiphersRC4 40/128
HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELCiphersRC4 56/128
HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELCiphersRC4 64/128
HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELCiphersRC4 128/128
HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELCiphersTriple DES 168/168
HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELCiphersAES 128/128
HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELCiphersAES 256/256

HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELHashesMD5
HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELHashesSHA

HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELKeyExchangeAlgorithmsDiffie-Hellman
HKLMSYSTEMCurrentControlSetControlSecurityProvidersSCHANNELKeyExchangeAlgorithmsPKCS

Each registry key has an “Enabled” value that is set. The protocols have an additional value named “DisabledByDefault” that is also set.

To reorder the cipher suites, IIS Crypto uses the following keys:

HKLMSYSTEMCurrentControlSetControlCryptographyConfigurationLocalSSL0010002

HKLMSOFTWAREPoliciesMicrosoftCryptographyConfigurationSSL0010002

The first registry key contains the list of supported cipher suites on the server. The second registry key is used to set the cipher suites order. These are the same keys that the group policy editor (gpedit.msc) use. Microsoft explains how to do this manually here. The full list of cipher suites supported is here.

IIS Crypto also supports pre-defined templates that can be set with a single button click:

PCI – Disables everything except SSL 3.0, TLS 1.0, TLS 1.1, TLS 1.2, RC4 128, Triple DES 168, AES 128, AES 256, MD5, SHA1, DH and PKCS.

FIPS 140-2 – Disables everything except TLS 1.0, TLS 1.1, TLS 1.2, Triple DES 168, AES 128, AES 256, SHA1, DH and PKCS.

BEAST – The same as PCI, but also reorders the cipher suite as follows:

TLS_RSA_WITH_RC4_128_SHA
TLS_RSA_WITH_RC4_128_MD5
TLS_RSA_WITH_AES_128_CBC_SHA256
TLS_RSA_WITH_AES_128_CBC_SHA
TLS_RSA_WITH_AES_256_CBC_SHA256
TLS_RSA_WITH_AES_256_CBC_SHA
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P384
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA_P256
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA_P384
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA_P256
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA_P384
TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256_P256
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256_P256
TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384_P384
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384_P384
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA_P256
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA_P384
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA_P256
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA_P384
TLS_DHE_DSS_WITH_AES_128_CBC_SHA256
TLS_DHE_DSS_WITH_AES_128_CBC_SHA
TLS_DHE_DSS_WITH_AES_256_CBC_SHA256
TLS_DHE_DSS_WITH_AES_256_CBC_SHA

Feel free to leave a comment if you have any questions.

A new version of IIS Crypto has been released. This new version adds in a BEAST template to re-order the SSL cipher suite putting RC4 at the top to mitigate the attack. We have also added .Net 4.0 binaries for Windows 2012 as it does not install .Net 2.0 by default.

IIS Crypto has been updated to fix the security exception issue if it is run under a non-administrator account. Thanks for all of the bug reports, keep them coming!