antipaucity

fighting the lack of good ideas

4 places to check your website’s ssl/tls security settings

Qualys – https://www.ssllabs.com/ssltest

High-Tech Bridge – https://www.htbridge.com/ssl

Comodo – https://sslanalyzer.comodoca.com

SSL Checker – https://www.sslchecker.com/sslchecker

ssl configuration for apache 2.4 on centos 7 with let’s encrypt

In follow-up to previous posts I’ve had about SSL (specifically with Let’s Encrypt), here is the set of SSL configurations I use with all my sites. These, if used correctly, should score you an “A+” with no warnings from ssllabs.com. Note: I have an improved entropy package installed (twuewand). This is adapted from the Mozilla config generator with specific options added for individual sites and/or to match Let’s Encrypt’s recommendations.

Please note: you will need to modify the config files to represent your own domains, if you choose to use these as models.

[/etc/httpd/conf.d/defaults.conf]

#SSL options for all sites
Listen 443
SSLPassPhraseDialog  builtin
SSLSessionCache         shmcb:/var/cache/mod_ssl/scache(512000)
SSLSessionCacheTimeout  300
Mutex sysvsem default
SSLRandomSeed startup builtin
SSLRandomSeed startup file:/dev/urandom  1024
# requires twuewand to be installed
SSLRandomSeed startup exec:/bin/twuewand 64
SSLRandomSeed connect builtin
SSLRandomSeed connect file:/dev/urandom 1024
SSLCryptoDevice builtin
# the SSLSessionTickets directive should work - but on Apache 2.4.6-45, it does not
#SSLSessionTickets       off
SSLCompression          off
SSLHonorCipherOrder	on
# there may be an unusual use case for enabling TLS v1.1 or 1 - but I don't know what that would be
SSLProtocol all -SSLv2 -SSLv3 -TLSv1 -TLSv1.1
SSLCipherSuite ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256
SSLOptions +StrictRequire
SSLUseStapling on
SSLStaplingResponderTimeout 5
SSLStaplingReturnResponderErrors off
SSLStaplingCache        shmcb:/var/run/ocsp(128000)

#all unknown requests get domain.tld (over http)
<VirtualHost *:80>
    DocumentRoot /var/html
    ServerName domain.tld
    ServerAlias domain.tld *.domain.tld
    ErrorLog logs/domain-error_log
    CustomLog logs/domain-access_log combined
    ServerAdmin user@domain.tld
    <Directory "/var/html">
         Options All +Indexes +FollowSymLinks
         AllowOverride All
         Order allow,deny
         Allow from all
    </Directory>
</VirtualHost>

SetOutputFilter DEFLATE
AddOutputFilterByType DEFLATE text/html text/plain text/xml text/javascript text/css text/php

[/etc/httpd/conf.d/z-[sub-]domain-tld.conf]

<Virtualhost *:80>
    ServerName domain.tld
# could use * instead of www if you don't use subdomains for anything special/separate
    ServerAlias domain.tld www.domain.tld
    Redirect permanent / https://domain.tld/
</VirtualHost>

<VirtualHost *:443>
    SSLCertificateFile /etc/letsencrypt/live/domain.tld/cert.pem
    SSLCertificateKeyFile /etc/letsencrypt/live/domain.tld/privkey.pem
# if you put "fullchain.pem" here, you will get an error from ssllabs
    SSLCertificateChainFile /etc/letsencrypt/live/domain.tld/chain.pem
    DocumentRoot /var/www/domain
    ServerName domain.tld
    ErrorLog logs/domain-error_log
    CustomLog logs/domain-access_log \
          "%t %h %{SSL_PROTOCOL}x %{SSL_CIPHER}x \"%r\" %b"
    ServerAdmin user@domain.tld

# could put this in defaults.conf - I prefer it in each site config
    SSLEngine on

<Files ~ "\.(cgi|shtml|phtml|php3?)$">
    SSLOptions +StdEnvVars
</files>
<Directory "/var/www/cgi-bin">
    SSLOptions +StdEnvVars
</Directory>

SetEnvIf User-Agent ".*MSIE.*" \
         nokeepalive ssl-unclean-shutdown \
         downgrade-1.0 force-response-1.0

    <Directory "/var/www/domain">
         Options All +Indexes +FollowSymLinks
         AllowOverride All
         Order allow,deny
         Allow from all
    </Directory>

</VirtualHost>

I use the z....conf formatting to ensure all site-specific configs are loaded after everything else. That conveniently breaks every site into its own config file, too.

The config file for a non-https site is much simpler:

<VirtualHost *:80>
    DocumentRoot /var/www/domain
    ServerName domain.tld
    ServerAlias domain.tld *.domain.tld
    ErrorLog logs/domain-error_log
    CustomLog logs/domain-access_log combined
    ServerAdmin user@domain.tld
    <Directory "/var/www/domain">
         Options All +Indexes +FollowSymLinks
         AllowOverride All
         Order allow,deny
         Allow from all
    </Directory>
</VirtualHost>

If you’re running something like Nextcloud, you may want to turn on Header always set Strict-Transport-Security "max-age=15552000; includeSubDomains" in the <VirtualHost&gt directive for the site. I haven’t decided yet if I should put this in every SSL-enabled site’s configs or not.

automated let’s encrypt ssl certificate renewal on centos 7

In my how-to for Let’s Encrypt, I gave an example script that can be called via cron (or manually) which will renew Let’s Encrypt SSL certificates under CentOS 6.

If you want to do it on CentOS 7 (which is what I am now running), use the following:

cd ~/letsencrypt
git pull
systemctl stop httpd.service
~/letsencrypt/letsencrypt-auto --agree-tos --keep --rsa-key-size 2048 --standalone certonly -m user@domain.tld -d domain.tld [-d sub.domain.tld [-d ...]]
systemctl start httpd.service

Now, what does this script do? Step by step:

  1. clear-out the last grab of the Let’s Encrypt git repo (there’s probably a better way to do this, but I don’t know what it is)
  2. go to root’s home (/root)
  3. clone-down the Let’s Encrypt toolset
  4. stop httpd (Apache in my case, though you might be running nginx or something else
  5. run the cert tool in automated form:
    1. agree to terms of service
    2. keep current cert if it doesn’t need to be updated
    3. key size of 2048 bits
    4. run the standalone webserver to verify “ownership” of the domain
    5. generate just the cert
    6. administrative email (optional, but “encouraged”)
    7. domain(s) to issue cert for (must be individually identified with successive -d flags; LE does not support wildcard certs)
  6. restart httpd

I set mine to run @weekly in cron@monthly is likely good enough, but since it’s “free” to run, running slightly more than is necessary seems good to me. Plus, if you’re getting SSL certs for many domains all being served from the same server, they may have different expiration dates, so running more often is better.

My crontab entry for renewing certs:

@weekly /root/renew-le-ssl.sh

let’s encrypt centos 6 – truly free ssl

There’s been quite a bit of excitement surrounding Let’s Encrypt recently – a truly 100% free SSL issuer.

Last week I helped a friend of mine get his first Let’s Encrypt certificate generated and configured for his website. One of the things I found incredibly frustrating is that Let’s Encrypt does not have a package for Red Hat/CentOS/Fedora! Ignoring such a massive installed base seems monumentally dumb – so I hope that they correct it soon. Until they do, however, here’s a tutorial that should cover the gotchas for getting Let’s Encrypt to work on a CentOS 6 server with Apache 2.

The documentation (as of 06 Jan 2015) on the Let’s Encrypt website is in error in a few places (or, at least, not as correct as is could/should be). One big thing to note, for example, is that it says Python 2.6 is supported (the current release for RHEL/CentOS 6). If you run the certificate generator without the --debug flag, though, it will error-out saying Python 2.6 is not supported.

While I used an existing CentOS 6 server, I’ll start this tutorial as I have many others – by telling you to go get a CentOS 6 server from Digital Ocean or Chunk Host.

Preliminaries

Login as root (or a sudo-privileged account – but root is easier), and install Apache, Python, and SSLyum install httpd python mod_ssl.

Also enable the EPEL repository: yum install epel-repository (available from the CentOS Extras repository. I’m going to assume you are familiar with configuring Apache, and will only provide the relevant snippets from ssl.conf herein.

Now that the basics are done, let’s move to Let’s Encrypt. I ran the tool in interactive mode (which is going to require ncurses to be available – it’s probably already installed on your system) – but you’ll want to add a crontab entry since Let’s Encrypt certs expire after 90 days, so I’ll compact the interactive session into a single command-line call at the end, which you’ll need to “know” how to do, since the --help argument doesn’t do anything yet (that I could find).

Initial Certificate Creation

First, grab the latest Let’s Encrypt from GitHub:
git clone https://github.com/letsencrypt/letsencrypt && cd letsencrypt

Stop Apache: service httpd stop. Let’s Encrypt is going to try to bind to ports 80 and 443 to ensure you have control the domain.

Now run the letsencrypt-auto tool – in debug mode so it’ll work with Python 2.6: ./letsencrypt-auto --debug certonly.

Use certonly because the plugins to automate installing for Apache and Nginx don’t work on CentOS yet.

Enter your domain name(s) for which you want to issue a certificate. If you accept incoming connections to www.domain.tld and domain.tld, be sure to put both in the list (likewise, if you have, say, blog.domain.tld that you want included).

Enter an administrative email address.

When the tool finishes, it’ll put symlinks in /etc/letsencrypt/live/domain.tld, with the “actual” certs in /etc/letsencrypt/archive/domain.tld. We’re going to reference the symlinks in /etc/letsencrypt/live/domain.tld next.

Edit /etc/httpd/conf.d/ssl.conf (I prefer emacs – but use whatever you prefer), and add the following lines in your VirtualHost directive:
SSLCertificateFile /etc/letsencrypt/live/domain.tld/fullchain.pem
SSLCertificateKeyFile /etc/letsencrypt/live/domain.tld/privkey.pem
SSLCACertificateFile /etc/letsencrypt/live/domain.tld/cert.pem

Restart Apacheservice httpd start.

Try hitting https://domain.tld in your web browser – and you should be golden!

Automating Renewal

Create a small shell script called renew-LE-certs.sh somewhere you’ll remember where it is – like /root:
service httpd stop
# add additional '-d' entries for more subdomains
/path/to/letsencrypt/letsencrypt-auto --debug --keep --agree-tos --rsa-key-size 2048 certonly -m ssladmin@domain.tld -d domain.tld -d www.domain.tld
service httpd start

For your crontab entry, do the following to setup monthly cert renewal:
@monthly /path/to/renew-LE-certs.sh

on using nmap to help find tlstorm-affected devices

You may have heard of the recently-discovered/-published TLStorm vulnerability that affects – at least – APC SmartUPS devices.

One of the prime issues highlighted is the embedded nanoSSL library that APC has used on these systems.

If you want to find out if your system is affected, the following nmap except should start you towards a solution:

for octet in {30..39}; do (nmap -A -T4 192.168.0.$octet > nmap-192.168.0.$octet.out &) ; done

This will kick-off nmap to run in parallel. When they all finish (you can monitor how many are running using ps aux | grep nmap), you can then process the files rapidly thusly:

grep -i nano nmap*.out

If nanoSSL has been found, you’ll get a listing of all IPs running it (since you cleverly named your files with the IP in the name).

The mitigations you choose to implement have been explained well in the articles linked above, but finding these systems can be a pain.

Hope this helps someone 🙂

determining the ‘legitimacy’/’reliability’ of a domain

I’ve recently been asked by several people to investigate websites (especially e-commerce ones) for reliability/legitimateness.

Thought someone else may find my process useful, and/or have some ideas on how to improve it ?

So here goes:

  1. Pop a terminal window (I’m on a Mac, so I open Terminal – feel free to use your terminal emulator of choice (on Windows, you’ll need to have the Subsystem for Linux or Cygwin installed))
    1. Type whois <domain.tld> | less
    2. Look at all of the following:
      • Creation (Creation Date: 2006-02-22T01:12:10Z)
      • Expiration (Registry Expiry Date: 2023-02-22T01:12:10Z)
      • Name server(s) (NS3.PAIRNIC.COM)
      • Registral URL (http://www.pairdomains.com)
      • Registrar (Pair Domains)
      • Contact info (should [generally] be anonymized in some manner)
    3. Possible flags:
      • If the domain’s under 2 years old, and/or the registration period is less than a year (we can talk about when short registrations may make sense in the comments)
      • If the name servers are “out of the country” (which, of course, will vary based on where you are)
      • If the contact info isn’t anonymized
  2. Load the website in question in a browser (use an ingonito and/or proxied tab, if you like) and review the following types of pages:
    • Contact Us
      • Where are they located?
      • Does the location stated match what you expect based on the whois response?
    • About Us
      • Does it read “naturally” in the language it purports to be written in?
        • Ie, does it sound like a native speaker wrote it, or does it sound stiltedly/mechanically translated?
    • Does it match what is in the whois record and the Contact Us page?
    • Do they provide social media links (Twitter, Facebook, LinkedIn, Instagram, etc)?
      • What do their social media presence(s) say about them?
    • Return/Refund Policy (for ecommerce sites only)
      • What is the return window?
      • How much will be charged to send it back and/or restorck it?
    • Shipping Policy (for ecommerce sites only)
      • How long from submitting an order to when it ships to when it arrives?
      • Where is it shipping from?
    • Privacy Policy (only applies if you may be sharing data with them (ecommerce, creating accounts, etc)
      • What do they claim they will (and will not) do with your private information?
  3. Is the site running over TLS/SSL?
    • You should see a little padlock icon in your browser’s address bar
    • Click that icon, and read what the browser reports about the SSL certificate used
    • Given that running over TLS is 100% free, there is absolutely NO reason for a site to NOT use SSL (double especially if they’re purporting to be an ecommerce site)

Reviewing these items usually takes me about 2-3 minutes.

It’s not foolproof (after all, better fools are invented every day), but it can give you a good overview and relative confidence level in the site in question.

sshuttle – a simple transparent proxy vpn over ssh

I found out about sshuttle from a random tweet that happened to catch my eye.

Here’s the skinny (from the readme):

  • Your client machine (or router) is Linux, FreeBSD, or MacOS.
  • You have access to a remote network via ssh.
  • You don’t necessarily have admin access on the remote network.
  • The remote network has no VPN, or only stupid/complex VPN protocols (IPsec, PPTP, etc). Or maybe you are the admin and you just got frustrated with the awful state of VPN tools.
  • You don’t want to create an ssh port forward for every single host/port on the remote network.
  • You hate openssh’s port forwarding because it’s randomly slow and/or stupid.
  • You can’t use openssh’s PermitTunnel feature because it’s disabled by default on openssh servers; plus it does TCP-over-TCP, which has terrible performance.

Here’s how I set it up on my Mac

Install homebrew:

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"

Install sshuttle (as a regular user):

brew install sshuttle

Test the connection to a server you have:

sudo sshuttle -r <user>@host.tld -x host.tld 0/0 -vv

I also made sure that my target server could be connected-to via certificate for my local root user – but you can use a password if you prefer.

Check your IP address:

curl https://ipv4.cf

Once you make sure the connection works, Ctrl-C to end the session.

Then setup an alias in your shell’s .profile (for me, it’s .bash_profile):

alias vpn='sudo sshuttle -r <user>@domain.tld -x domain.tld 0/0'

Other things you can do

According to the full docs, there are a lot more things you can do with sshuttle – including running it on your router, thereby VPN’ing your whole LAN through an endpoint! You can also run it in server mode.

This is a super useful little utility!