looking for ssl certs with keys less than 1024bits
On September 11, 2012 Microsoft released an update that will block SSL certificates that use RSA keys less than 1024bits. If you are looking for a way to discover if there are weak certificates in use on your network one tool you can use is good ol nmap. nmap has a handy dandy scripting engine that you can use to do things like look for certain vulnerabilities. Lucky for us their is a script built into the default bundle that comes with nmap that we can use to find SSL certs and their bit length.
A basic scan would look like this dumping everything to standard out:
nmap -sV -sC -v network/subnet
If you have a lot of hosts to scan you probably need a report:
nmap -sV -sC -v —webxml -oX sslCerts.xml 192.168.1.1/24
xsltproc sslCerts.xml sslCerts.html
Then you can open sslCerts.html in your browser and voila. This assumes you have xsltproc available on your OS of course.