Skip to content

Checking For Outdated Ciphers

Keeping the software up-to-date on your machine is important and evermore so for security reasons. However, some people forget to update their configurations when they update their software. Running an old config could be just as dangerous as running old software!

I am going to show how to check a network-listening service for outdated ciphers. First make sure you have nmap installed. Second grab the nmap script named 'ssl-enum-ciphers.nse' from the official nmap website.

Example checking a webserver:

nmap --script ssl-enum-ciphers -p 443


I ran this against an internal webserver that is running Ubuntu 16.04:

Starting Nmap 7.91 ( https://nmap.org ) at 2021-08-06 12:38 PDT
Nmap scan report for 10.53.209.159
Host is up (0.00015s latency).

PORT STATE SERVICE
443/tcp open https
| ssl-enum-ciphers:
| TLSv1.0:
| ciphers:
| TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA (dh 2048) - C
| TLS_DHE_RSA_WITH_AES_128_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_256_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_SEED_CBC_SHA (dh 2048) - A
| TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA (secp256r1) - C
| TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_RC4_128_SHA (secp256r1) - C
| TLS_RSA_WITH_3DES_EDE_CBC_SHA (rsa 2048) - C
| TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_AES_256_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_CAMELLIA_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_CAMELLIA_256_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_RC4_128_MD5 (rsa 2048) - C
| TLS_RSA_WITH_RC4_128_SHA (rsa 2048) - C
| TLS_RSA_WITH_SEED_CBC_SHA (rsa 2048) - A
| 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
| TLSv1.1:
| ciphers:
| TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA (dh 2048) - C
| TLS_DHE_RSA_WITH_AES_128_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_256_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_SEED_CBC_SHA (dh 2048) - A
| TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA (secp256r1) - C
| TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_RC4_128_SHA (secp256r1) - C
| TLS_RSA_WITH_3DES_EDE_CBC_SHA (rsa 2048) - C
| TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_AES_256_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_CAMELLIA_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_CAMELLIA_256_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_RC4_128_MD5 (rsa 2048) - C
| TLS_RSA_WITH_RC4_128_SHA (rsa 2048) - C
| TLS_RSA_WITH_SEED_CBC_SHA (rsa 2048) - A
| 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
| TLSv1.2:
| ciphers:
| TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA (dh 2048) - C
| TLS_DHE_RSA_WITH_AES_128_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_128_CBC_SHA256 (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_256_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_256_CBC_SHA256 (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 (dh 2048) - A
| TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_SEED_CBC_SHA (dh 2048) - A
| TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA (secp256r1) - C
| TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (secp256r1) - A
| TLS_ECDHE_RSA_WITH_RC4_128_SHA (secp256r1) - C
| TLS_RSA_WITH_3DES_EDE_CBC_SHA (rsa 2048) - C
| TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_AES_128_CBC_SHA256 (rsa 2048) - A
| TLS_RSA_WITH_AES_128_GCM_SHA256 (rsa 2048) - A
| TLS_RSA_WITH_AES_256_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_AES_256_CBC_SHA256 (rsa 2048) - A
| TLS_RSA_WITH_AES_256_GCM_SHA384 (rsa 2048) - A
| TLS_RSA_WITH_CAMELLIA_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_CAMELLIA_256_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_RC4_128_MD5 (rsa 2048) - C
| TLS_RSA_WITH_RC4_128_SHA (rsa 2048) - C
| TLS_RSA_WITH_SEED_CBC_SHA (rsa 2048) - A
| 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
|_ least strength: C

Nmap done: 1 IP address (1 host up) scanned in 0.43 seconds


We want our target to show the least strength cipher as "A" and we do not want NULL ciphers or options. This particular host is running Apache2, so we need to edit /etc/apache2/mods-enabled/ssl.conf and look for or add a line like this:

SSLCipherSuite HIGH:!aNULL


Then restart apache2 and retest:

Starting Nmap 7.91 ( https://nmap.org ) at 2021-08-06 12:55 PDT
Nmap scan report for 10.53.209.159
Host is up (0.00015s latency).

PORT STATE SERVICE
443/tcp open https
| ssl-enum-ciphers:
| TLSv1.0:
| ciphers:
| TLS_DHE_RSA_WITH_AES_128_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_256_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA (dh 2048) - 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_RSA_WITH_CAMELLIA_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_CAMELLIA_256_CBC_SHA (rsa 2048) - A
| compressors:
| NULL
| cipher preference: client
| TLSv1.1:
| ciphers:
| TLS_DHE_RSA_WITH_AES_128_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_256_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA (dh 2048) - 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_RSA_WITH_CAMELLIA_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_CAMELLIA_256_CBC_SHA (rsa 2048) - A
| compressors:
| NULL
| cipher preference: client
| TLSv1.2:
| ciphers:
| TLS_DHE_RSA_WITH_AES_128_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_128_CBC_SHA256 (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_256_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_256_CBC_SHA256 (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 (dh 2048) - A
| TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA (dh 2048) - A
| TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (secp256r1) - A
| TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_AES_128_CBC_SHA256 (rsa 2048) - A
| TLS_RSA_WITH_AES_128_GCM_SHA256 (rsa 2048) - A
| TLS_RSA_WITH_AES_256_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_AES_256_CBC_SHA256 (rsa 2048) - A
| TLS_RSA_WITH_AES_256_GCM_SHA384 (rsa 2048) - A
| TLS_RSA_WITH_CAMELLIA_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_CAMELLIA_256_CBC_SHA (rsa 2048) - A
| compressors:
| NULL
| cipher preference: client
|_ least strength: A

Nmap done: 1 IP address (1 host up) scanned in 0.47 seconds


Now we can see the lowest grade cipher in-use is an "A" which is what we want to see.

This was just a basic intro to cipher checking with nmap and I hope this article is helpful to someone. I enjoy receiving feedback; be it suggestions, corrections, or questions. Feel free to drop some love, be safe, and hack away!

Trackbacks

No Trackbacks

Comments

Display comments as Linear | Threaded

No comments

Add Comment

Enclosing asterisks marks text as bold (*word*), underscore are made via _word_.
Standard emoticons like :-) and ;-) are converted to images.
E-Mail addresses will not be displayed and will only be used for E-Mail notifications.

To prevent automated Bots from commentspamming, please enter the string you see in the image below in the appropriate input box. Your comment will only be submitted if the strings match. Please ensure that your browser supports and accepts cookies, or your comment cannot be verified correctly.
CAPTCHA

Form options