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Livius's avatar
Livius
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Sep 21, 2018

SSL ciphers questions

Hi,

 

I have a F5 pair running 11.5.2 where we are trying to mitigate Poodle vulnerability for a certain public facing VIP.

 

I have performed the following cipher config :

 

!SSLv3:!ADH:AES-GCM:RC4-SHA

 

What we want to achieve is RC4 and SSLv3 disabled, and ECDHE (PFS) prioritised over DHE (PFS, but weak at only 1024 bits) over RSA (non-PFS). There’s no issue with non-PFS, we just want to ensure, that the PFS ones are prioritised.

 

What’s currently live:

 

TLS 1.2 (suites in server-preferred order)

TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (0xc030) ECDH secp256r1 (eq. 3072 bits RSA) FS256 TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 (0x9f) DH 1024 bits FS WEAK256 TLS_RSA_WITH_AES_256_GCM_SHA384 (0x9d) WEAK256 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (0xc02f) ECDH secp256r1 (eq. 3072 bits RSA) FS128 TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 (0x9e) DH 1024 bits FS WEAK128 TLS_RSA_WITH_AES_128_GCM_SHA256 (0x9c) WEAK128 TLS_RSA_WITH_RC4_128_SHA (0x5) INSECURE128

 

TLS 1.1 (we could not determine if the server has a preference)

TLS_RSA_WITH_RC4_128_SHA (0x5) INSECURE128

 

TLS 1.0 (we could not determine if the server has a preference)

TLS_RSA_WITH_RC4_128_SHA (0x5) INSECURE128

 

Essentially, we have two issues here:

 

  1. The ordering of ECDHE > DHE > RSA is not correct.
  2. RC4 is enabled, CBC mode disabled. Should be the other way around.

Thanks. Liviu