I stumbled across a nasty XSS hole involving DNS A records. Found out today that an old subdomain that I had assigned an IP address to via a DNS A record was serving unexpected content—turned out I’d shut down the associated VPS and the IP had been recycled to someone else, so their content was now appearing under my domain. It strikes me that if you got really unlucky this could turn into an XSS hole—and that new server could even use Let’s Encrypt to obtain an HTTPS certificate for your subdomain.
I’ve added “audit your A records” to my personal security checklist.
Recent articles
- The last six months in LLMs, illustrated by pelicans on bicycles - 6th June 2025
- Tips on prompting ChatGPT for UK technology secretary Peter Kyle - 3rd June 2025
- How often do LLMs snitch? Recreating Theo's SnitchBench with LLM - 31st May 2025