How to Check for TLS Vulnerabilities Using Nmap

As you probably know, there’s a new encryption vulnerability called Logjam, which affects the Diffie-Hellman key exchange process.

There are number of online tools that can help you check for it, but it’s often not a good idea to ask random people to see if you’re vulnerable to something. They could be making a naughty Christmas list for all you know.

That’s where nmap comes in. With it’s NSE capabilities it can check for all sorts of vulns that you’d otherwise have to use one of those sites or roll your own code for:

nmap --script ssl-enum-ciphers -p 443 vulnerable.com

You can also pipe that to grep weak if you want to see just the weak ciphers:

Or you can pipe to grep DHE_EXPORT to see if you support the Diffie-Hellman Export algorithm that’s causing all the commotion.

Either way, you may want to keep this nmap-based TLS check handy since we seem to be conducing this excercise on a regular basis.