Hello all,
I have noticed an important difference in PANOS v8.0 in comparison with PANOS 7.x.x concerning the SSL settings for the GlobalProtect portal.
More specific, the famous site for SSL Server tests, Qualys SSL Labs presents PANOS 7.0.x with Grade A-, while for PANOS 8.0.x the grade is lowered to Grade B (worst).
This happends because, while in PANOS 8.0.x there is a wider support of ciphersuites fot TLSv1.2, the additional ciphersuites supported use weak weak Diffie-Hellman (DH) key exchange parameters. More specific, for some cipher suites, the DH key exchange is weak, as 1024-bits are being used.
More specific, for version 7.0.x, the Cipher Suites list is the following:
TLS 1.2 (suites in server-preferred order) | |
| TLS_RSA_WITH_AES_256_GCM_SHA384 (0x9d) | 256 |
| TLS_RSA_WITH_AES_128_GCM_SHA256 (0x9c) | 128 |
| TLS_RSA_WITH_AES_256_CBC_SHA256 (0x3d) | 256 |
| TLS_RSA_WITH_AES_128_CBC_SHA256 (0x3c) | 128 |
| TLS_RSA_WITH_AES_128_CBC_SHA (0x2f) | 128 |
while in PANOS 8.0.x the list is the following:
# TLS 1.2 (suites in server-preferred order) | |
| TLS_RSA_WITH_AES_256_GCM_SHA384 (0x9d) | 256 |
| TLS_RSA_WITH_AES_128_GCM_SHA256 (0x9c) | 128 |
| TLS_RSA_WITH_AES_256_CBC_SHA256 (0x3d) | 256 |
| TLS_RSA_WITH_AES_128_CBC_SHA256 (0x3c) | 128 |
| TLS_RSA_WITH_AES_128_CBC_SHA (0x2f) | 128 |
| TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (0xc014) ECDH secp521r1 (eq. 15360 bits RSA) FS | 256 |
| TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (0xc013) ECDH secp521r1 (eq. 15360 bits RSA) FS | 128 |
| TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (0xc030) ECDH secp521r1 (eq. 15360 bits RSA) FS | 256 |
| TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (0xc02f) ECDH secp521r1 (eq. 15360 bits RSA) FS | 128 |
| TLS_DHE_RSA_WITH_AES_256_CBC_SHA (0x39) DH 1024 bits FS WEAK | 256 |
| TLS_DHE_RSA_WITH_AES_128_CBC_SHA (0x33) DH 1024 bits FS WEAK | 128 |
| TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 (0x9f) DH 1024 bits FS WEAK | 256 |
| TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 (0x9e) DH 1024 bits FS WEAK | 128 |
The big question is how to disable these weak Forward Secrecy (FS) DH Weak key exchange exchange parameters as there is no option to manipulate these settings either from the Web UI or the CLI.
Maybe the new SSL/TLS Service Profile that appears in PANOS 7.1.x should have something for the CipherSuites and the Forward Secrecy (FS) key exchange parameters that need to be enabled/disabled/used (and the order they are being presented to the client's web browser.
Regards,
George G.
