Re: [PATCH] httpd: prefer AES-GCM ciphers over AES-CBC

[Michael Tremer <michael.tremer@ipfire.org>]

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Hi,

> On 15 May 2019, at 18:01, Peter Müller <peter.mueller(a)ipfire.org> wrote:
> 
> CBC ciphers are vulnerable to a bunch of attacks (being
> rather academic so far) such as MAC-then-encrypt or
> padding oracle.
> 
> These seem to be more serious (see
> https://blog.qualys.com/technology/2019/04/22/zombie-poodle-and-goldendoodle-vulnerabilities
> for further readings) which is why they should be used
> for interoperability purposes only.
> 
> I plan to remove AES-CBC ciphers for the WebUI at the
> end of the year, provided overall security landscape
> has not changed until that.

Yes, I can get behind this.

What do we do about OpenVPN where AES-256-CBC is the default?

> This patch changes the WebUI cipherlist to:
> TLS_CHACHA20_POLY1305_SHA256 TLSv1.3 Kx=any      Au=any  Enc=CHACHA20/POLY1305(256) Mac=AEAD
> TLS_AES_256_GCM_SHA384  TLSv1.3 Kx=any      Au=any  Enc=AESGCM(256) Mac=AEAD
> TLS_AES_128_GCM_SHA256  TLSv1.3 Kx=any      Au=any  Enc=AESGCM(128) Mac=AEAD
> ECDHE-ECDSA-CHACHA20-POLY1305 TLSv1.2 Kx=ECDH     Au=ECDSA Enc=CHACHA20/POLY1305(256) Mac=AEAD
> ECDHE-ECDSA-AES256-GCM-SHA384 TLSv1.2 Kx=ECDH     Au=ECDSA Enc=AESGCM(256) Mac=AEAD
> ECDHE-ECDSA-AES128-GCM-SHA256 TLSv1.2 Kx=ECDH     Au=ECDSA Enc=AESGCM(128) Mac=AEAD
> ECDHE-RSA-CHACHA20-POLY1305 TLSv1.2 Kx=ECDH     Au=RSA  Enc=CHACHA20/POLY1305(256) Mac=AEAD
> ECDHE-RSA-AES256-GCM-SHA384 TLSv1.2 Kx=ECDH     Au=RSA  Enc=AESGCM(256) Mac=AEAD
> ECDHE-RSA-AES128-GCM-SHA256 TLSv1.2 Kx=ECDH     Au=RSA  Enc=AESGCM(128) Mac=AEAD
> ECDHE-ECDSA-AES256-SHA384 TLSv1.2 Kx=ECDH     Au=ECDSA Enc=AES(256)  Mac=SHA384
> ECDHE-ECDSA-AES128-SHA256 TLSv1.2 Kx=ECDH     Au=ECDSA Enc=AES(128)  Mac=SHA256
> ECDHE-RSA-AES256-SHA384 TLSv1.2 Kx=ECDH     Au=RSA  Enc=AES(256)  Mac=SHA384
> ECDHE-RSA-AES128-SHA256 TLSv1.2 Kx=ECDH     Au=RSA  Enc=AES(128)  Mac=SHA256
> 
> (AES-CBC + ECDSA will be preferred over RSA for performance
> reasons. As this cipher order cannot be trivially rebuilt with
> OpenSSL cipher stings, it has to be hard-coded.)
> 
> All working clients will stay compatible.
> 
> Signed-off-by: Peter Müller <peter.mueller(a)ipfire.org>
> ---
> config/httpd/vhosts.d/ipfire-interface-ssl.conf | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/config/httpd/vhosts.d/ipfire-interface-ssl.conf b/config/httpd/vhosts.d/ipfire-interface-ssl.conf
> index f88a6a52a..0166c4920 100644
> --- a/config/httpd/vhosts.d/ipfire-interface-ssl.conf
> +++ b/config/httpd/vhosts.d/ipfire-interface-ssl.conf
> @@ -11,7 +11,7 @@
> 
>     SSLEngine on
>     SSLProtocol all -SSLv3 -TLSv1 -TLSv1.1
> -    SSLCipherSuite TLS_CHACHA20_POLY1305_SHA256:TLS_AES_256_GCM_SHA384:TLS_AES_128_GCM_SHA256:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA256
> +    SSLCipherSuite TLS_CHACHA20_POLY1305_SHA256:TLS_AES_256_GCM_SHA384:TLS_AES_128_GCM_SHA256:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA256
>     SSLHonorCipherOrder on
>     SSLCompression off
>     SSLSessionTickets off
> -- 
> 2.16.4