SSL Cipher Suite Order recommended

Question

Good day,

Could you give advice what the SSL Cipher Suite Order recommended at windows server 2019?

In the GPP default, I could saw the preset by default is below:

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TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384,TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256,TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384,TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256,TLS_RSA_WITH_AES_256_GCM_SHA384,TLS_RSA_WITH_AES_128_GCM_SHA256

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Brgds

Liu Wei

Answer 1

Ultimately, this is about finding the optimal balance between security and compatibility. Recommendation steer towards the former - but the environment you operate in might force you to consider the latter.

In general though:

1. Prioritize Stronger Cipher Suites:

• Prefer ECDHE (Elliptic Curve Diffie-Hellman Ephemeral) key exchange algorithms. These provide forward secrecy, meaning that even if an attacker later compromises the server's private key, past communications cannot be decrypted.
• Prioritize AES GCM (Galois/Counter Mode) over CBC (Cipher Block Chaining) due to better security properties (e.g., resistance to padding oracle attacks).
• Avoid RSA-based cipher suites unless absolutely necessary, as these are considered less secure compared to ECDHE-based suites.

1. Avoid Legacy Ciphers:
   • TLS 1.0 and TLS 1.1 are outdated and considered insecure.
   • Disable weak hash algorithms such as SHA1. Prefer SHA256 or stronger.

For example, your list might look like this:

TLS_AES_128_GCM_SHA256,TLS_AES_256_GCM_SHA384,
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
TLS_RSA_WITH_AES_256_GCM_SHA384,TLS_RSA_WITH_AES_128_GCM_SHA256

Beyond that:

• Disable Weak Ciphers: Specifically, you should disable the following ciphers:
• Ciphers with SHA1 or weaker hashes (e.g., TLS_RSA_WITH_AES_256_CBC_SHA, TLS_RSA_WITH_AES_128_CBC_SHA, etc.).
  • RC4-based ciphers (e.g., TLS_RSA_WITH_RC4_128_SHA).
  • 3DES ciphers (e.g., TLS_RSA_WITH_3DES_EDE_CBC_SHA).
• Disable SSL 2.0 and SSL 3.0: These older protocols are insecure and should be disabled in favor of TLS 1.2 or 1.3.
• Use Server Name Indication (SNI): To ensure secure connections and enable the use of multiple certificates on the same IP address, ensure that SNI is enabled.

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hth

Marcin