I'm running the below Nmap command to test the strength of the cipher suites I have used in my host
nmap -sV --script ssl-enum-ciphers -p 443 <host>
The Nmap doc says that Each ciphersuite is shown with a letter grade (A through F) indicating the strength of the connection and the output line beginning with Least strength shows the strength of the weakest cipher offered
When I ran the command against the host I got the output as shown below
| ssl-enum-ciphers:
| TLSv1.0:
| ciphers:
| TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA (dh 768) - E
| TLS_DHE_RSA_WITH_AES_128_CBC_SHA (dh 768) - C
| TLS_DHE_RSA_WITH_DES_CBC_SHA (dh 768) - E
| TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_RC4_128_MD5 (rsa 2048) - C
| TLS_RSA_WITH_RC4_128_SHA (rsa 2048) - C
| compressors:
| NULL
| cipher preference: client
| warnings:
| 64-bit block cipher 3DES vulnerable to SWEET32 attack
| 64-bit block cipher DES vulnerable to SWEET32 attack
| Broken cipher RC4 is deprecated by RFC 7465
| Ciphersuite uses MD5 for message integrity
| Key exchange (dh 768) of lower strength than certificate key
| TLSv1.1:
| ciphers:
| TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA (dh 768) - E
| TLS_DHE_RSA_WITH_AES_128_CBC_SHA (dh 768) - C
| TLS_DHE_RSA_WITH_DES_CBC_SHA (dh 768) - E
| TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_RC4_128_MD5 (rsa 2048) - C
| TLS_RSA_WITH_RC4_128_SHA (rsa 2048) - C
| compressors:
| NULL
| cipher preference: client
| warnings:
| 64-bit block cipher 3DES vulnerable to SWEET32 attack
| 64-bit block cipher DES vulnerable to SWEET32 attack
| Broken cipher RC4 is deprecated by RFC 7465
| Ciphersuite uses MD5 for message integrity
| Key exchange (dh 768) of lower strength than certificate key
| TLSv1.2:
| ciphers:
| TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA (dh 768) - E
| TLS_DHE_RSA_WITH_AES_128_CBC_SHA (dh 768) - C
| TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 (secp256r1) - A
| TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_RC4_128_MD5 (rsa 2048) - C
| TLS_RSA_WITH_RC4_128_SHA (rsa 2048) - C
| compressors:
| NULL
| cipher preference: client
| warnings:
| 64-bit block cipher 3DES vulnerable to SWEET32 attack
| Broken cipher RC4 is deprecated by RFC 7465
| Ciphersuite uses MD5 for message integrity
| Key exchange (dh 768) of lower strength than certificate key
|_ least strength: E
My questions
- As per the doc, the Ciphers marked as "E" is the weak cipher and in another way can I consider the cipher marked as "A" as the strong cipher?
- TLS_RSA_WITH_AES_128_CBC_SHA is marked as "A" here, but in some discussions, I have observed it is mentioned as WEAK. Is it because of the SHA1 usage? if so why this is rated as "A" in NMAP?
- I have configured the below cipher list on my server.
ciphers="SSL_RSA_WITH_RC4_128_MD5,SSL_RSA_WITH_RC4_128_SHA,SSL_DHE_RSA_WITH_DES_CBC_SHA,SSL_DHE_RSA_WITH_3DES_EDE_CBC_SHA,TLS_RSA_WITH_AES_128_CBC_SHA,TLS_DHE_RSA_WITH_AES_128_CBC_SHA,TLS_RSA_WITH_AES_256_CBC_SHA,TLS_DHE_RSA_WITH_AES_256_CBC_SHA,TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256,TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256"
but the ciphers such as SSL_RSA_WITH_RC4_128 is not available in the Nmap output, instead, there are ciphers like TLS_RSA_WITH_RC4_128, what is the reason for this? Can we use SSL and TLS interchangeably in the Ciphers?
- Even though I have added the TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 as a cipher in my server, it wasn't available in the Nmap results, what might be the reason for this?
PS: I'm using JDK 1.7 as the underlying JDK version for the server