Today I was asked how can you verify if a WebServer is running TLS (Transport Layer Security) 1.2?
How Do You Run NMAP’s ssl-enum-ciphers Script to Check TLS Support?
User Summary
This script repeatedly initiates SSLv3 (SSL version 3) / TLS connections, each time trying a new cipher or compressor while recording whether a host accepts or rejects it. The end result is a list of all the ciphersuites and compressors that a server accepts.
Each ciphersuite is shown with a letter grade (A through F) indicating the strength of the connection. The grade is based on the cryptographic strength of the key exchange and of the stream cipher. The message integrity (hash) algorithm choice is not a factor. The output line beginning with Least strength shows the strength of the weakest cipher offered.
more…[https://nmap.org/nsedoc/scripts/ssl-enum-ciphers.html]
Example Usage
nmap -sV –script ssl-enum-ciphers -p 443
Script Output
PORT STATE SERVICE REASON
443/tcp open https syn-ack
| ssl-enum-ciphers:
| TLSv1.0:
| ciphers:
| TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA (secp256r1) - A
| TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (secp256r1) - A
| TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_AES_256_CBC_SHA (rsa 2048) - A
| TLS_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA (secp256r1) - C
| TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA (secp256r1) - C
| TLS_RSA_WITH_3DES_EDE_CBC_SHA (rsa 2048) - C
| TLS_ECDHE_ECDSA_WITH_RC4_128_SHA (secp256r1) - C
| TLS_ECDHE_RSA_WITH_RC4_128_SHA (secp256r1) - C
| TLS_RSA_WITH_RC4_128_SHA (rsa 2048) - C
| TLS_RSA_WITH_RC4_128_MD5 (rsa 2048) - C
| compressors:
| NULL
| cipher preference: server
| warnings:
| 64-bit block cipher 3DES vulnerable to SWEET32 attack
| Broken cipher RC4 is deprecated by RFC 7465
| Ciphersuite uses MD5 for message integrity
| Weak certificate signature: SHA1
| TLSv1.2:
| ciphers:
| TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 (secp256r1) - A
| TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 (secp256r1) - A
| TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA (secp256r1) - A
| TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (secp256r1) - A
| TLS_RSA_WITH_AES_128_GCM_SHA256 (rsa 2048) - A
| TLS_RSA_WITH_AES_256_GCM_SHA384 (rsa 2048) - A
| TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_AES_256_CBC_SHA (rsa 2048) - A
| TLS_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA (secp256r1) - C
| TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA (secp256r1) - C
| TLS_RSA_WITH_3DES_EDE_CBC_SHA (rsa 2048) - C
| TLS_ECDHE_ECDSA_WITH_RC4_128_SHA (secp256r1) - C
| TLS_ECDHE_RSA_WITH_RC4_128_SHA (secp256r1) - C
| TLS_RSA_WITH_RC4_128_SHA (rsa 2048) - C
| TLS_RSA_WITH_RC4_128_MD5 (rsa 2048) - C
| compressors:
| NULL
| cipher preference: server
| warnings:
| 64-bit block cipher 3DES vulnerable to SWEET32 attack
| Broken cipher RC4 is deprecated by RFC 7465
| Ciphersuite uses MD5 for message integrity
|_ least strength: CFrequently Asked Questions
What NMAP command do you run to check which TLS versions a web server supports?
Run nmap -sV --script ssl-enum-ciphers -p 443 <host>. The script initiates repeated SSLv3/TLS handshakes with different cipher suites and returns a full list of accepted ciphers organized by protocol version (TLSv1.0, TLSv1.2, etc.).
What do the letter grades in the ssl-enum-ciphers output mean?
Each cipher suite receives a grade from A to F based on the cryptographic strength of the key exchange and stream cipher. Grade A indicates strong modern ciphers (e.g., ECDHE with AES-GCM); Grade C indicates weak or deprecated ones like 3DES or RC4. The least strength line shows the weakest cipher the server will accept.
What security warnings should you watch for in the ssl-enum-ciphers output? Key warnings include: 3DES being vulnerable to the SWEET32 attack, RC4 being deprecated per RFC 7465, MD5 being used for message integrity, and a weak SHA1 certificate signature. Any of these indicate the server should be reconfigured to offer only strong TLS 1.2+ cipher suites.