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Archive for the ‘Let’s Encrypt (letsencrypt/certbot)’ Category

5 days before the Let’s Encrypt’s Root Certificate is expiring!

Posted by jpluimers on 2021/09/24

Only 5 days left to take a close look at both your web-clients (including back-end clients!) and servers to prevent potential Let’s Encrypt mayhem.

Last week, [Wayback] Scott Helme published about [Wayback/Archive.is] Let’s Encrypt’s Root Certificate is expiring!

Let’s Encrypt has done loads of work over the past lustrum to prevent trouble like cross-signing, issuing the successor certificates, and more.

The problem is that people like you and me have refrained from keeping their clients and servers up-to-date, so some security issues will occur. Hopefully they are limited to non-functioning communication and not leaking of data.

It is about this DST Root CA X3 certificate, used by the vast majority of Let’s Encrypt certificates, [Wayback/Archive.is] Certificate Checker: CN=DST Root CA X3, O=Digital Signature Trust Co.:

DST Root CA X3
Certificate Trusted anchor certificate
Subject DN CN=DST Root CA X3, O=Digital Signature Trust Co.
Issuer DN CN=DST Root CA X3, O=Digital Signature Trust Co.
Serial Number 44AFB080D6A327BA893039862EF8406B
Valid  to  Key RSAPublicKey (2048 bit)
SHA1 Hash DAC9024F54D8F6DF94935FB1732638CA6AD77C13 MD5 Hash 410352DC0FF7501B16F0028EBA6F45C5
SKI C4A7B1A47B2C71FADBE14B9075FFC41560858910 AKI

Quoting Scott, these clients likely will fail, so need attention:

  • OpenSSL <= 1.0.2
  • Windows < XP SP3
  • macOS < 10.12.1
  • iOS < 10 (iPhone 5 is the lowest model that can get to iOS 10)
  • Android < 7.1.1 (but >= 2.3.6 will work if served ISRG Root X1 cross-sign)
  • Mozilla Firefox < 50
  • Ubuntu < 16.04
  • Debian < 8
  • Java 8 < 8u141
  • Java 7 < 7u151
  • NSS < 3.26
  • Amazon FireOS (Silk Browser)

On the server side, you can help Android devices by using a Let’s Encrypt certificate that is cross-signed with the ISRG Root X1 certificate [Wayback/Archive.is] Certificate Checker: CN=ISRG Root X1, O=Internet Security Research Group, C=US:

ISRG Root X1
Certificate
Subject DN CN=ISRG Root X1, O=Internet Security Research Group, C=US
Issuer DN CN=DST Root CA X3, O=Digital Signature Trust Co.
Serial Number 4001772137D4E942B8EE76AA3C640AB7
Valid  to  Key RSAPublicKey (4096 bit)
SHA1 Hash 933C6DDEE95C9C41A40F9F50493D82BE03AD87BF MD5 Hash C1E1FF07F9F688498274D1A18053EABF
SKI 79B459E67BB6E5E40173800888C81A58F6E99B6E AKI C4A7B1A47B2C71FADBE14B9075FFC41560858910

Via [Archive.is] Scott Helme on Twitter: “There are only 10 days left until the Let’s Encrypt root certificate expires and there are still questions over what the impact will be! Full details here: …” which links to the above article showing a nice graph of the current Let’s Encrtypt root certificate setup:

–jeroen

Posted in Communications Development, Development, Encryption, https, HTTPS/TLS security, Internet protocol suite, Let's Encrypt (letsencrypt/certbot), Power User, Security, Software Development, TCP, TLS, Web Development | Leave a Comment »

SSL certificates – not optional | Open Query Pty Ltd

Posted by jpluimers on 2020/09/04

Some tips on using the certbot for Let’s Encrypt and the support for wildcard certificates through DNS updates: [WayBack] SSL certificates – not optional | Open Query Pty Ltd

–jeroen

Posted in Encryption, HTTPS/TLS security, Let's Encrypt (letsencrypt/certbot), Power User, Security | Leave a Comment »

Expect your sites to be accessed over https and ensure your certificates match

Posted by jpluimers on 2020/05/22

igOver the last lustrum, there has been a steady increase in https usage. It crossed the 30% mark early 2016, crossing the 50% mark early 2017 and 80% mark early 2018, even the https-by-default configuration is now pretty large:

Ever since 2012, but especially with the increased HTTPS adoption, you can expect more and more users to run plugins like HTTPS Everywhere – Wikipedia which switch a request from insecure http to secure https.

Users are right: http is a thing from the past and https is the way to go forward.

This means you need to ensure your web sites to serve https well, which starts with servicing https at all and includes serving a correct https certificate for them.

Often, IT departments are not even aware that when serving http for a domain, the endpoint also answers https requests for that domain.

WordPress.com was really bad at this when servicing custom domains ordered from their premium plans. Which was odd, as customers payed for those domains. They solved this in spring 2016, they started to use LetsEncrypt (which started in 2015) for their certificates: [WayBack] HTTPS Everywhere: Encryption for All WordPress.com Sites — The WordPress.com Blog.

So this is what you need to do for all your subdomains:

  1. check if they are serviced by http
  2. contemplate (in fact urge to) servicing https for them
  3. when an endpoint services https, ensure the certificates for it are correct
  4. do not mix https and http in the same site
  5. avoid redirecting from https to http

Adopting https can be tedious, but many sites have already done this and wrote down their experiences, even back in 2016:

Many sites still get their https configuration wrong though, and this post is a reminder to myself for one of them.

Read the rest of this entry »

Posted in Encryption, HTTPS/TLS security, Let's Encrypt (letsencrypt/certbot), Power User, Security | Leave a Comment »

Viewing certbot installed certificates and their expiry dates

Posted by jpluimers on 2020/01/24

A simple tip on the certbot command-line from [WayBackUser Guide — Certbot 0.19.0.dev0 documentation – Managing certificates (Automatically enable HTTPS on your website with EFF’s Certbot, deploying Let’s Encrypt certificates.):

To view a list of the certificates Certbot knows about, run the certificates subcommand:

certbot certificates

This returns information in the following format:

Found the following certs:
  Certificate Name: example.com
    Domains: example.com, www.example.com
    Expiry Date: 2017-02-19 19:53:00+00:00 (VALID: 30 days)
    Certificate Path: /etc/letsencrypt/live/example.com/fullchain.pem
    Private Key Path: /etc/letsencrypt/live/example.com/privkey.pem

Via: [WayBack] It there a command to show how many days certificate you have? – Server – Let’s Encrypt Community Support

–jeroen

Posted in Encryption, Let's Encrypt (letsencrypt/certbot), Power User, Security | Leave a Comment »

if you allow users to register email addresses on your domain, make sure they can’t get: admin@ administrator@ hostmaster@…

Posted by jpluimers on 2019/12/16

Great tip from: [Archive.isMichal Špaček on Twitter: “Friendly reminder: if you allow users to register email addresses on your domain, make sure they can’t get: admin@ administrator@ hostmaste… https://t.co/wUHXrQC2J0”:

 Friendly reminder: if you allow users to register email addresses on your domain, make sure they can’t get:
  • admin@
  • administrator@
  • hostmaster@
  • postmaster@
  • webmaster@ (and others from RFC 2142)

otherwise users might be able to get an HTTPS certificate for your domain.

–jeroen

Read the rest of this entry »

Posted in Encryption, https, Let's Encrypt (letsencrypt/certbot), Power User, Security | Leave a Comment »

 
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