[pfg]

I don't know where they got the information about the certificate being issued 5 months prior to the attack, but that's not what Certificate Transparency shows. Here's the certificate that was issued on the day of the attack[1]. Let's Encrypt hasn't issued any certificates prior to that[2].

Another fun fact: It took them about a month to revoke the certificate in question. They didn't even bother revoking a second certificate[3] (valid for a subdomain). Heh, at least this will make a good example when discussion the pros of short-lived certificates.

[1]: https://crt.sh/?id=47675898

[2]: https://crt.sh/?Identity=%25.banrisul.com.br&iCAID=16418

[3]: https://crt.sh/?id=47630635