Weak TLS ciphers detected by a Qualys scan and not used in SSLCONFIG

[CSCO11645642]

Hello All,

Please find below SSLCONFIG defined on ESA (C395 - 14.2.3-031) and the result of the Qualys scan :

About ECDHE-RSA-NULL-SHA, I tried to disable -aNULL (Inbound and Outbound) but I still see NULL-SHA256 when I did "Verify" TLSv1.2 and confirmed by Qualys.

Regarding ECDHE-RSA-DES-CBC3-SHA, I don't understand why the Qualys scan found it because the settings DES CBC3 SHA1 are not enabled in the SSLCONFIG configuration.

Can anyone help me or have any ideas on how to disable these two threats ?

Many Thanks !

[charella · Accepted solution]

CSCO11645642wrote:
About ECDHE-RSA-NULL-SHA, I tried to disable -aNULL (Inbound and Outbound) but I still see NULL-SHA256 when I did "Verify" TLSv1.2 and confirmed by Qualys.
Regarding ECDHE-RSA-DES-CBC3-SHA, I don't understand why the Qualys scan found it because the settings DES CBC3 SHA1 are not enabled in the SSLCONFIG configuration.
Can anyone help me or have any ideas on how to disable these two threats?

I see the output you referred to using verify:TLSv1.2.
That reveals what is offered in the build of OpenSSL. That is why we as admin modify the string to include/exclude ciphers.
That would not solve the hard findings from your scanner but does show that it is not in use if configured within the ciphers.
To completely remove the null I would recommend upgrading to 15.5 when it is released around April. ( I put a sample output from 15.5 below..)

You may know all this, but I’m adding it just in case.
Try this when using the verify command. Copy your string from the GUI SSL Configuration page for each inbound, outbound or https.
Then use those in the verify.


* The ciphers are present in the ESA but are removed from use based on the configuration.
Example from 14.2
AES128:AES256:!SRP:!AESGCM+DH+aRSA:!AESGCM+RSA:!aNULL:!kRSA:@STRENGTH:-aNULL:-EXPORT:-IDEA:!DHE-RSA-AES256-SHA

Sslconfig > verify
Enter the ssl cipher you want to verify.
[]> AES128:AES256:!SRP:!AESGCM+DH+aRSA:!AESGCM+RSA:!aNULL:!kRSA:@STRENGTH:-aNULL:-EXPORT:-IDEA:!DHE-RSA-AES256-SHA

ECDHE-RSA-AES256-GCM-SHA384 TLSv1.2 Kx=ECDH Au=RSA Enc=AESGCM(256) Mac=AEAD
ECDHE-ECDSA-AES256-GCM-SHA384 TLSv1.2 Kx=ECDH Au=ECDSA Enc=AESGCM(256) Mac=AEAD
ECDHE-RSA-AES256-SHA384 TLSv1.2 Kx=ECDH Au=RSA Enc=AES(256) Mac=SHA384
ECDHE-ECDSA-AES256-SHA384 TLSv1.2 Kx=ECDH Au=ECDSA Enc=AES(256) Mac=SHA384
ECDHE-RSA-AES256-SHA SSLv3 Kx=ECDH Au=RSA Enc=AES(256) Mac=SHA1
ECDHE-ECDSA-AES256-SHA SSLv3 Kx=ECDH Au=ECDSA Enc=AES(256) Mac=SHA1
DHE-DSS-AES256-GCM-SHA384 TLSv1.2 Kx=DH Au=DSS Enc=AESGCM(256) Mac=AEAD
DHE-PSK-AES256-CBC-SHA SSLv3 Kx=DHEPSK Au=PSK Enc=AES(256) Mac=SHA1
DHE-RSA-AES256-SHA256 TLSv1.2 Kx=DH Au=RSA Enc=AES(256) Mac=SHA256
DHE-DSS-AES256-SHA256 TLSv1.2 Kx=DH Au=DSS Enc=AES(256) Mac=SHA256
DHE-DSS-AES256-SHA SSLv3 Kx=DH Au=DSS Enc=AES(256) Mac=SHA1
PSK-AES256-CBC-SHA SSLv3 Kx=PSK Au=PSK Enc=AES(256) Mac=SHA1
ECDHE-RSA-AES128-GCM-SHA256 TLSv1.2 Kx=ECDH Au=RSA Enc=AESGCM(128) Mac=AEAD
ECDHE-ECDSA-AES128-GCM-SHA256 TLSv1.2 Kx=ECDH Au=ECDSA Enc=AESGCM(128) Mac=AEAD
ECDHE-RSA-AES128-SHA256 TLSv1.2 Kx=ECDH Au=RSA Enc=AES(128) Mac=SHA256
ECDHE-ECDSA-AES128-SHA256 TLSv1.2 Kx=ECDH Au=ECDSA Enc=AES(128) Mac=SHA256
ECDHE-RSA-AES128-SHA SSLv3 Kx=ECDH Au=RSA Enc=AES(128) Mac=SHA1
ECDHE-ECDSA-AES128-SHA SSLv3 Kx=ECDH Au=ECDSA Enc=AES(128) Mac=SHA1
DHE-DSS-AES128-GCM-SHA256 TLSv1.2 Kx=DH Au=DSS Enc=AESGCM(128) Mac=AEAD
DHE-RSA-AES128-SHA256 TLSv1.2 Kx=DH Au=RSA Enc=AES(128) Mac=SHA256
DHE-DSS-AES128-SHA256 TLSv1.2 Kx=DH Au=DSS Enc=AES(128) Mac=SHA256
DHE-RSA-AES128-SHA SSLv3 Kx=DH Au=RSA Enc=AES(128) Mac=SHA1
DHE-DSS-AES128-SHA SSLv3 Kx=DH Au=DSS Enc=AES(128) Mac=SHA1
PSK-AES128-CBC-SHA SSLv3 Kx=PSK Au=PSK Enc=AES(128) Mac=SHA1



To verify you could use an open string to connect to the esa and a pcap to see what ciphers are offered.
openssl s_client -debug -starttls smtp -cipher NULL-SHA256 -connect 10.122.144.170:25
openssl s_client -debug -starttls smtp -cipher ECDHE-RSA-AES128-SHA -connect 10.122.144.170:25

-----------

The sslconfig > verify command; paste your whole string of configured ciphers when testing. > copy from the gui for formatting purposes

Example:
HIGH:MEDIUM:@STRENGTH:!aNULL:!eNULL:!MD5:!PSK:!DSS:!RC2:!SEED:!ECDSA:!ADH:!IDEA:!3DES:!SSLv2


The ciphers exist but the settings remove them from use.
To test with the “verify” check, paste the full cipher set, preferably copied from the GUI format


NEXT: I ran your same test using verify TLSv1.2 in our latest AsyncOS 15.5 (to be released in about a month) and the NULL is not present.

Enter the ssl cipher you want to verify.
[]> TLSv1.2

TLS_AES_256_GCM_SHA384 TLSv1.3 Kx=any Au=any Enc=AESGCM(256) Mac=AEAD
TLS_CHACHA20_POLY1305_SHA256 TLSv1.3 Kx=any Au=any Enc=CHACHA20/POLY1305(256) Mac=AEAD
TLS_AES_128_GCM_SHA256 TLSv1.3 Kx=any Au=any Enc=AESGCM(128) Mac=AEAD
ECDHE-ECDSA-AES256-GCM-SHA384 TLSv1.2 Kx=ECDH Au=ECDSA Enc=AESGCM(256) Mac=AEAD
ECDHE-RSA-AES256-GCM-SHA384 TLSv1.2 Kx=ECDH Au=RSA Enc=AESGCM(256) Mac=AEAD
DHE-DSS-AES256-GCM-SHA384 TLSv1.2 Kx=DH Au=DSS Enc=AESGCM(256) Mac=AEAD
DHE-RSA-AES256-GCM-SHA384 TLSv1.2 Kx=DH Au=RSA Enc=AESGCM(256) Mac=AEAD
ECDHE-ECDSA-CHACHA20-POLY1305 TLSv1.2 Kx=ECDH Au=ECDSA Enc=CHACHA20/POLY1305(256) Mac=AEAD
ECDHE-RSA-CHACHA20-POLY1305 TLSv1.2 Kx=ECDH Au=RSA Enc=CHACHA20/POLY1305(256) Mac=AEAD
DHE-RSA-CHACHA20-POLY1305 TLSv1.2 Kx=DH Au=RSA Enc=CHACHA20/POLY1305(256) Mac=AEAD
ECDHE-ECDSA-AES256-CCM TLSv1.2 Kx=ECDH Au=ECDSA Enc=AESCCM(256) Mac=AEAD
DHE-RSA-AES256-CCM TLSv1.2 Kx=DH Au=RSA Enc=AESCCM(256) Mac=AEAD
ECDHE-ECDSA-AES128-GCM-SHA256 TLSv1.2 Kx=ECDH Au=ECDSA Enc=AESGCM(128) Mac=AEAD
ECDHE-RSA-AES128-GCM-SHA256 TLSv1.2 Kx=ECDH Au=RSA Enc=AESGCM(128) Mac=AEAD
DHE-DSS-AES128-GCM-SHA256 TLSv1.2 Kx=DH Au=DSS Enc=AESGCM(128) Mac=AEAD
DHE-RSA-AES128-GCM-SHA256 TLSv1.2 Kx=DH Au=RSA Enc=AESGCM(128) Mac=AEAD
ECDHE-ECDSA-AES128-CCM TLSv1.2 Kx=ECDH Au=ECDSA Enc=AESCCM(128) Mac=AEAD
DHE-RSA-AES128-CCM TLSv1.2 Kx=DH Au=RSA Enc=AESCCM(128) Mac=AEAD
ECDHE-ECDSA-AES256-SHA384 TLSv1.2 Kx=ECDH Au=ECDSA Enc=AES(256) Mac=SHA384
ECDHE-RSA-AES256-SHA384 TLSv1.2 Kx=ECDH Au=RSA Enc=AES(256) Mac=SHA384
DHE-RSA-AES256-SHA256 TLSv1.2 Kx=DH Au=RSA Enc=AES(256) Mac=SHA256
DHE-DSS-AES256-SHA256 TLSv1.2 Kx=DH Au=DSS Enc=AES(256) Mac=SHA256
ECDHE-ECDSA-CAMELLIA256-SHA384 TLSv1.2 Kx=ECDH Au=ECDSA Enc=Camellia(256) Mac=SHA384
ECDHE-RSA-CAMELLIA256-SHA384 TLSv1.2 Kx=ECDH Au=RSA Enc=Camellia(256) Mac=SHA384
DHE-RSA-CAMELLIA256-SHA256 TLSv1.2 Kx=DH Au=RSA Enc=Camellia(256) Mac=SHA256
DHE-DSS-CAMELLIA256-SHA256 TLSv1.2 Kx=DH Au=DSS Enc=Camellia(256) Mac=SHA256
ADH-CAMELLIA256-SHA256 TLSv1.2 Kx=DH Au=None Enc=Camellia(256) Mac=SHA256
ECDHE-ECDSA-AES128-SHA256 TLSv1.2 Kx=ECDH Au=ECDSA Enc=AES(128) Mac=SHA256
ECDHE-RSA-AES128-SHA256 TLSv1.2 Kx=ECDH Au=RSA Enc=AES(128) Mac=SHA256
DHE-RSA-AES128-SHA256 TLSv1.2 Kx=DH Au=RSA Enc=AES(128) Mac=SHA256
DHE-DSS-AES128-SHA256 TLSv1.2 Kx=DH Au=DSS Enc=AES(128) Mac=SHA256
ECDHE-ECDSA-CAMELLIA128-SHA256 TLSv1.2 Kx=ECDH Au=ECDSA Enc=Camellia(128) Mac=SHA256
ECDHE-RSA-CAMELLIA128-SHA256 TLSv1.2 Kx=ECDH Au=RSA Enc=Camellia(128) Mac=SHA256
DHE-RSA-CAMELLIA128-SHA256 TLSv1.2 Kx=DH Au=RSA Enc=Camellia(128) Mac=SHA256
DHE-DSS-CAMELLIA128-SHA256 TLSv1.2 Kx=DH Au=DSS Enc=Camellia(128) Mac=SHA256
ADH-CAMELLIA128-SHA256 TLSv1.2 Kx=DH Au=None Enc=Camellia(128) Mac=SHA256
RSA-PSK-AES256-GCM-SHA384 TLSv1.2 Kx=RSAPSK Au=RSA Enc=AESGCM(256) Mac=AEAD
DHE-PSK-AES256-GCM-SHA384 TLSv1.2 Kx=DHEPSK Au=PSK Enc=AESGCM(256) Mac=AEAD
RSA-PSK-CHACHA20-POLY1305 TLSv1.2 Kx=RSAPSK Au=RSA Enc=CHACHA20/POLY1305(256) Mac=AEAD
DHE-PSK-CHACHA20-POLY1305 TLSv1.2 Kx=DHEPSK Au=PSK Enc=CHACHA20/POLY1305(256) Mac=AEAD
ECDHE-PSK-CHACHA20-POLY1305 TLSv1.2 Kx=ECDHEPSK Au=PSK Enc=CHACHA20/POLY1305(256) Mac=AEAD
DHE-PSK-AES256-CCM TLSv1.2 Kx=DHEPSK Au=PSK Enc=AESCCM(256) Mac=AEAD
AES256-GCM-SHA384 TLSv1.2 Kx=RSA Au=RSA Enc=AESGCM(256) Mac=AEAD
AES256-CCM TLSv1.2 Kx=RSA Au=RSA Enc=AESCCM(256) Mac=AEAD
PSK-AES256-GCM-SHA384 TLSv1.2 Kx=PSK Au=PSK Enc=AESGCM(256) Mac=AEAD
PSK-CHACHA20-POLY1305 TLSv1.2 Kx=PSK Au=PSK Enc=CHACHA20/POLY1305(256) Mac=AEAD
PSK-AES256-CCM TLSv1.2 Kx=PSK Au=PSK Enc=AESCCM(256) Mac=AEAD
RSA-PSK-AES128-GCM-SHA256 TLSv1.2 Kx=RSAPSK Au=RSA Enc=AESGCM(128) Mac=AEAD
DHE-PSK-AES128-GCM-SHA256 TLSv1.2 Kx=DHEPSK Au=PSK Enc=AESGCM(128) Mac=AEAD
DHE-PSK-AES128-CCM TLSv1.2 Kx=DHEPSK Au=PSK Enc=AESCCM(128) Mac=AEAD
AES128-GCM-SHA256 TLSv1.2 Kx=RSA Au=RSA Enc=AESGCM(128) Mac=AEAD
AES128-CCM TLSv1.2 Kx=RSA Au=RSA Enc=AESCCM(128) Mac=AEAD
PSK-AES128-GCM-SHA256 TLSv1.2 Kx=PSK Au=PSK Enc=AESGCM(128) Mac=AEAD
PSK-AES128-CCM TLSv1.2 Kx=PSK Au=PSK Enc=AESCCM(128) Mac=AEAD
AES256-SHA256 TLSv1.2 Kx=RSA Au=RSA Enc=AES(256) Mac=SHA256
CAMELLIA256-SHA256 TLSv1.2 Kx=RSA Au=RSA Enc=Camellia(256) Mac=SHA256
AES128-SHA256 TLSv1.2 Kx=RSA Au=RSA Enc=AES(128) Mac=SHA256
CAMELLIA128-SHA256 TLSv1.2 Kx=RSA Au=RSA Enc=Camellia(128) Mac=SHA256


[]> verify

Enter the ssl cipher you want to verify.
[]> TLSv1.0

TLS_AES_256_GCM_SHA384 TLSv1.3 Kx=any Au=any Enc=AESGCM(256) Mac=AEAD
TLS_CHACHA20_POLY1305_SHA256 TLSv1.3 Kx=any Au=any Enc=CHACHA20/POLY1305(256) Mac=AEAD
TLS_AES_128_GCM_SHA256 TLSv1.3 Kx=any Au=any Enc=AESGCM(128) Mac=AEAD
ECDHE-ECDSA-AES128-SHA TLSv1 Kx=ECDH Au=ECDSA Enc=AES(128) Mac=SHA1
ECDHE-RSA-AES128-SHA TLSv1 Kx=ECDH Au=RSA Enc=AES(128) Mac=SHA1
ECDHE-PSK-AES256-CBC-SHA384 TLSv1 Kx=ECDHEPSK Au=PSK Enc=AES(256) Mac=SHA384
RSA-PSK-AES256-CBC-SHA384 TLSv1 Kx=RSAPSK Au=RSA Enc=AES(256) Mac=SHA384
DHE-PSK-AES256-CBC-SHA384 TLSv1 Kx=DHEPSK Au=PSK Enc=AES(256) Mac=SHA384
ECDHE-PSK-CAMELLIA256-SHA384 TLSv1 Kx=ECDHEPSK Au=PSK Enc=Camellia(256) Mac=SHA384
RSA-PSK-CAMELLIA256-SHA384 TLSv1 Kx=RSAPSK Au=RSA Enc=Camellia(256) Mac=SHA384
DHE-PSK-CAMELLIA256-SHA384 TLSv1 Kx=DHEPSK Au=PSK Enc=Camellia(256) Mac=SHA384
PSK-AES256-CBC-SHA384 TLSv1 Kx=PSK Au=PSK Enc=AES(256) Mac=SHA384
PSK-CAMELLIA256-SHA384 TLSv1 Kx=PSK Au=PSK Enc=Camellia(256) Mac=SHA384
ECDHE-PSK-AES128-CBC-SHA256 TLSv1 Kx=ECDHEPSK Au=PSK Enc=AES(128) Mac=SHA256
ECDHE-PSK-AES128-CBC-SHA TLSv1 Kx=ECDHEPSK Au=PSK Enc=AES(128) Mac=SHA1
RSA-PSK-AES128-CBC-SHA256 TLSv1 Kx=RSAPSK Au=RSA Enc=AES(128) Mac=SHA256
DHE-PSK-AES128-CBC-SHA256 TLSv1 Kx=DHEPSK Au=PSK Enc=AES(128) Mac=SHA256
ECDHE-PSK-CAMELLIA128-SHA256 TLSv1 Kx=ECDHEPSK Au=PSK Enc=Camellia(128) Mac=SHA256
RSA-PSK-CAMELLIA128-SHA256 TLSv1 Kx=RSAPSK Au=RSA Enc=Camellia(128) Mac=SHA256
DHE-PSK-CAMELLIA128-SHA256 TLSv1 Kx=DHEPSK Au=PSK Enc=Camellia(128) Mac=SHA256
PSK-AES128-CBC-SHA256 TLSv1 Kx=PSK Au=PSK Enc=AES(128) Mac=SHA256
PSK-CAMELLIA128-SHA256 TLSv1 Kx=PSK Au=PSK Enc=Camellia(128) Mac=SHA256




TLS 1.3 ciphers:

TLS_AES_256_GCM_SHA384

TLS_CHACHA20_POLY1305_SHA256

TLS_AES_128_GCM_SHA256

[CSCO11645642]

Thank you for your reply.
I will check next Monday the verify command with SSL configuration “Inbound” and confirm this to you.

About Asyncos 15.5, I think it’s a good option but in my opinion, this release will be too “young” to install it immediately. Please let me know which AsyncOS release Cisco recommended currently ?

Also, I saw that TLS 1.3 will be proposed, do you confirm this setting? Our audit recommended enabling it.

[CSCO11645642]

Issue resolved using ssl cipher configuration : AES128:AES256:!SRP:!AESGCM+DH+aRSA:!AESGCM+RSA:!aNULL:!kRSA:@STRENGTH:-aNULL:-EXPORT:-IDEA:!DHE-RSA-AES256-SHA

Thanks for your help