Code to Test Lets Encrypt CAA Bug.https://medium.com/@muchilwa/all-you-need-to-know-about-lets-encrypt-caa-bugs-part-1-aa93e51ec0b1
The script is a hack written in python 3 It allows you to run the check against a single domain or from a text file containing a list of domain. Main purpose is to allow the community identify affected sites and do something about it. I also needed to learn how to python 3.

• Python 3
• Internet access

• Clone the repor.
• Run the vulnech.py script and follow the prompts

run

./vulncheck.py

Once executed, the scripts will generate a txt file with your results.
You can find data to kick you off from https://github.com/ScottHelme/le-scan by Scott Helme. Another useful links:

• https://github.com/hannob/lecaa
• https://www.cyberciti.biz/security/letsencrypt-is-revoking-certificates-on-march-4/