c0d3 :: j0rg3

A collection of tips, tricks and snips. A proud Blosxom weblog. All code. No cruft.

Sun, 19 Feb 2017

Privacy: perspective and primer.

Hello friends.

While the overall telos of this blog is to, generally speaking, convey code snippets and inspire the personal projects of others, today we’re going to do something a smidgeon different.

This will be a layman’s look at varied dimensions of information security from a comfortable distance. Over the years, I’ve secured servers, operating systems, medical data, networks, communications and I’ve unsecured many of these same things. The topics are too sprawling to be covered in a quick summary — but let’s find a point of entry.

Those of us who are passionate about information security are well aware of how daunting is the situation. For newcomers, it sometimes seems rather impossible. Pick any subject and there are probably well-informed and convincing experts in diametric equidistance from any “happy medium”.

Let’s imagine that (like most of us) you don’t have anything spectacular to protect. However, you dislike the idea of our ever-dissolving privacy. Therefore you want to encrypt communications. Maybe you begin to use Signal. However, there are criticisms that there is a “backdoor” (there is not). Further, there are accusations that open source projects are coded by those who can’t get real jobs. Conversely, open source projects are widely open for peer review. If it worries one enough they are free to review code themselves.

PGP can encrypt content but concerns surround algorithmic selections. Some are worried about metadata crumbs. Of course, there’s nothing preventing the frequent switching of keys and email addresses. You could use BitMessage, any number of chat solutions or drop at paste bins.

Let’s leave those concerns aside for when you’ve figured out what you’re intending to protect. These arguments surround any subject in information security and we’re not going to investigate them on a case by case basis. Least, not in this post.

At the coarsest granularity, the question is analogous to the practicality of locking your doors or sealing your post envelopes. Should I take measures toward privacy?

My opinion is rather predictable: of course you should!

There’s a very pragmatic explanation. If there ever comes a day when you should like to communicate privately, that’s a terrible time to start learning.

Take the easy road and start using some of the myriad tools and services available.

Should you decide to take InfoSec seriously, you’ll need to define a threat model.
That is: What am I protecting? From whom am I protecting? (e.g. what are probable attack vectors?)

That’s where you need to make choices about trusting products, protocols, methods, algorithms, companies, servers, et cet. Those are all exciting subjects to explore but all too often brushing up against them can be exasperating and cause premature burn-out.

That in mind, let’s employ the philosophy that any effort toward security is better than none and take a look at a few points where one might get wetted-toes.

If you have questions or want specific advice, there are several ways below to initiate a secure conversation with me.

 

Secure your browser:

  • Privacy Badger: Block tracking
  • HTTPS Everywhere: Increase your encryptioning
  • uBlock: Advertisements are for others
  •  

    Secure communications:

  • Mailvelope: PGP email encryption for your major webmail provider (e.g., Gmail) | contact | pubkey
  • Tutanota: Encrypted webmail | Kontakt
  • Protonmail: Well-established provider of PGP encrypted webmail, featuring 2FA | kontakta
  • BitMessage: P2P encrypted communications protocol | contact: BM-2D9tDkYEJSTnEkGDKf7xYA5rUj2ihETxVR | Bitmessage channel list
  •   [ Bitmessage in a Docker container ]

  • BitMessage.ch: BitMessage email gateway | contact
  • BitMsg.me: Online BitMessage service
  • Keybase.io: Keybase maps your identity to your public keys, and vice versa
  • Signal: PGP encrypted TXT messages
  • Wire: Encrypted chat, video and calls
  • RIOT: Open-source, IRC-based, Matrix; run your own server
  • Wickr: Encrypted ephemeral chat
  •   [ n.b. Wickr’s .deb package seeks a unicode library (libicu52) which is not available to a recent Kali (or anything) install; .deb file is based on Ubuntu’s 2014 LTS release. Wickr in a Docker container ]

     

    Explore alternate nets (e.g., Deep Web, Dark Net):

  • MaidSafe: Promising new alt-web project
  • Qubes: a reasonably secure operating system
  • FreeNet: Alt-net based primarily on already knowing with whom you intend to collaborate
  • Bitmask: VPN solution to anonymize your traffic
  • TAILS: A live operating system based on the Tor network
  • TorBrowser: Stand-alone browser for Tor (less secure than TAILS)
  • Whonix: the most secure (and complex) way to access the Tor network
  • i2p: an other approach to creating a secure and private alternate web
  • Morph.is: fun alt-net, aimed at producing The World Brain. Although, it’s future looks a lot less promising since the lead dev was killed.
  • ZeroNet: one more encrypted anonymous net
  • Have fun and compute safely!


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    Permalink: 20170219.privacy.prespective.primer

    Fri, 17 Feb 2017

    The making of a Docker: Part I - Bitmessage GUI with SSH X forwarding

    Lately, I’ve been doing a lot of work from a laptop running Kali. Engaged in pursuit of a new job, I’m brushing up on some old tools and skills, exploring some bits that have changed.

    My primary desktop rig is currently running Arch because I love the fine grain control and the aggressive releases. Over the years, I’ve Gentoo’d and Slacked, Crunchbanged, BSD’d, Solarised, et cet. And I’ve a fondness for all of them, especially the security-minded focus of OpenBSD. But, these days we’re usually on Arch or Kali. Initially, I went with Black Arch on the laptop but I felt the things and ways I was fixing things were too specific to my situation to be good material for posts.

    Anyway, I wanted to get Bitmessage running, corresponding to another post I have in drafts. On Kali, it wasn’t going well so I put it on the Arch box and just ran it over the network. A reasonable solution if you’re in my house but also the sort of solution that will keep a hacker up at night.

    If you’re lucky, there’s someone maintaining a package for the piece of software that you want to run. However, that’s often not the case.

    If I correctly recall, to “fix” the problem with Bitmessage on Kali would’ve required the manual installation an older version of libraries that were already present. Those libraries should, in fact, be all ebony and ivory, living together in harmony. However, I just didn’t love the idea of that solution. I wanted to find an approach that would be useful on a broader scale.

    Enter containerization/virtualization!

    Wanting the lightest solution, I quickly went to Docker and realized something. I have not before built a Docker container for a GUI application. And Bitmessage’s CLI/daemon mode doesn’t provide the fluid UX that I wanted. Well, the easy way to get a GUI out of a Docker container is to forward DISPLAY as an evironment variable (i.e., docker run -e DISPLAY=$DISPLAY). Splendid!

    Except that it doesn’t work on current Kali which is using QT4. There’s a when graphical apps are run as root and though it is fixed in QT5, we are using current Kali. And that means we are, by default, uid 0 and QT4.

    I saw a bunch of workarounds that seemed to have spotty (at best) rates of success including seting QT’s graphics system to Native and giving Xorg over to root. They, mostly, seemed to be cargo cult solutions.

    What made the most sense to my (generally questionable) mind was to use X forwarding. Since I had already been running Bitmessage over X forwarding from my Arch box, I knew it should work just the same.

    To be completely truthful, the first pass I took at this was with Vagrant mostly because it’s SO easy. Bring up your Vagrant Box and then:
    vagrant ssh -- -X
    Viola!

    Having proof of concept, I wanted a Docker container. The reason for this is practical. Vagrant, while completely awesome, has substantially more overhead than Docker by virtualizing the kernel. We don’t want a separate kernel running for each application. Therefore Docker is the better choice for this project.

    Also, we want this whole thing to be seemless. We want to run the command bitmessage and it should fire up with minimal awkwardness and hopefully no extra steps. That is we do not want to run the Docker container then SSH into it and execute Bitmessage as individual steps. Even though that’s going to be how we begin.

    The Bitmessage wiki accurately describes how to install the software so we’ll focus on the SSH setup. Though when we build the Dockerfile we will need to add SSH to the list from the wiki.

    We’re going to want the container to start so that the SSH daemon is ready. Until then we can’t SSH (with X forwarding) into the container. Then we’ll want to use SSH to kick off the Bitmessage application, drawing the graphical interface using our host system’s X11.

    We’re going to take advantage of Docker’s -v --volume option which allows us to specify a directory on our host system to be mounted inside our container. Using this feature, we’ll generate our SSH keys on the host and make them automatically available inside the container. We’ll tuck the keys inside the directory that Bitmessage uses for storing its configuration and data. That way Bitmessage’s configuration and stored messages can be persistent between runs — and all of your pieces are kept in a single place.

    When we generate the container /etc/ssh/sshd_config is configured to allow root login without password only (i.e., using keys). So here’s how we’ll get this done:
    mkdir -p ~/.config/PyBitmessage/keys #Ensure that our data directories exist
    cd ~/.config/PyBitmessage/keys
    ssh-keygen -b 4096 -P "" -C $"$(whoami)@$(hostname)-$(date -I)" -f docker-bitmessage-keys #Generate our SSH keys
    ln -fs docker-bitmessage-keys.pub authorized_keys #for container to see pubkey

    Build our container (sources available at Github and Docker) and we’ll make the script to handle Bitmessage to our preferences. #!/bin/bash
    # filename: bitmessage
    set -euxo pipefail

    # open Docker container:
    # port 8444 available, sharing local directories for SSH and Bitmessage data
    # detatched, interactive, pseudo-tty (-dit)
    # record container ID in $DID (Docker ID)
    DID=$(docker run -p 8444:8444 -v ~/.config/PyBitmessage/:/root/.config/PyBitmessage -v ~/.config/PyBitmessage/keys/:/root/.ssh/ -dit j0rg3/bitmessage-gui bash)

    # find IP address of new container, record in $DIP (Docker IP)
    DIP=$(docker inspect $DID | grep IPAddress | cut -d '"' -f 4)

    # pause for one second to allow container's SSHD to come online
    sleep 1

    # SSH into container and execute Bitmessage
    ssh -oStrictHostKeyChecking=no -oUserKnownHostsFile=/dev/null -oIdentityFile=~/.config/PyBitmessage/keys/docker-bitmessage-keys -X $DIP ./PyBitmessage/src/bitmessagemain.py

    # close container if Bitmessage is closed
    docker kill $DID

    Okay, let’s make it executable: chmod +x bitmessage

    Put a link to it where it can be picked up system-wide: ln -fs ~/docker-bitmessage/bitmessage /usr/local/bin/bitmessage

    There we have it! We now have a functional Bitmessage inside a Docker container. \o/

    In a future post we’ll look at using eCryptfs to further protect our Bitmessage data stores.

      Project files: Github and Docker


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    Permalink: 20170217.making.a.docker.bitmessage

    Mon, 02 Jan 2017

    Securing a new server

    Happy new year! New year means new servers, right?

    That provides its own set of interesting circumstances!

    The server we’re investigating in this scenario was chosen for being a dedicated box in a country that has quite tight privacy laws. And it was a great deal offered on LEB.

    So herein is the fascinating bit. The rig took a few days for the provider to set up and, upon completion, the password for SSHing into the root account was emailed out. (o_0)

    In very security-minded considerations, that means that there was a window of opportunity for bad guys to work on guessing the password before its owner even tuned in. That window remains open until the server is better secured. Luckily, there was a nice interface for reinstalling the OS permitting its purchaser to select a password.

    My preferred approach was to script the basic lock-down so that we can reinstall the base OS and immediately start closing gaps.


    In order:

  • Set up SSH keys (scripted)
  • Disable password usage for root (scripted)
  • Install and configure IPset (scripted. details in next post)
  • Install and configure fail2ban
  • Install and configure PortSentry

  • In this post, we’re focused on the first two steps.


    The tasks to be handled are:

  • Generate keys
  • Configure local SSH to use key
  • Transmit key to target server
  • Disable usage of password for ‘root’ account

  • We’ll use ssh-keygen to generate a key — and stick with RSA for ease. If you’d prefer ECC then you’re probably reading the wrong blog but feel encouraged to contact me privately.

    The code:

    #!/bin/bash
    #configure variables
    remote_host="myserver.com"
    remote_user="j0rg3"
    remote_pass="thisisaratheraquitecomplicatedpasswordbatterystaple" # https://xkcd.com/936/
    local_user=`whoami`
    local_host=`hostname`
    local_date=`date -I`
    local_filename=~/.ssh/id_rsa@$remote_host

    #generate key without passphrase
    ssh-keygen -b 4096 -P "" -C $local_user@local_host-$local_date -f $local_filename

    #add reference to generated key to local configuration
    printf '%s\n' "Host $remote_host" "IdentityFile $local_filename" >> ~/.ssh/config

    #copy key to remote host
    sshpass -p $remote_pass ssh-copy-id $remote_user@$remote_host

    #disable password for root on remote
    ssh $remote_user@$remote_host "cp /etc/ssh/sshd_config /etc/ssh/sshd_config.bak && sed -i '0,/RE/s/PermitRootLogin yes/PermitRootLogin no/' /etc/ssh/sshd_config"

    We just run this script soon as the OS is reinstalled and we’re substantially safer. As a Deb8 install, quickly pulling down fail2ban and PortSentry makes things quite a lot tighter.

    In another post, we’ll visit the 2017 version of making a DIY script to batten the hatches using a variety of publicly provided blocklists.

    Download here:
        ssh_quick_fix.sh


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    Permalink: 20170102.securing.a.new.server