Category: Linux

Ubuntu 22.04 LTS (Jammy Jellyfish) ships Firefox as a snap, but some people (like me) may prefer installing it from .deb packages to retain control over upgrades or to keep extensions working.

Luckily there is still a PPA serving firefox (and thunderbird) debs at https://launchpad.net/~mozillateam/+archive/ubuntu/ppa maintained by the Mozilla Team. (Thank you! 🙏)

Block Ubuntu’s Snap Version of Firefox

Block the Ubuntu archive’s version that just pulls in the snap by pinning it

$ cat /etc/apt/preferences.d/firefox-no-snap 
Package: firefox*
Pin: release o=Ubuntu*
Pin-Priority: -1

Remove Firefox Snap

Remove the transitional package and the Firefox snap itself

sudo apt purge firefox
sudo snap remove firefox

Install Firefox DEB

Install the DEB packaged Firefox from the Mozilla PPA

sudo add-apt-repository ppa:mozillateam/ppa
sudo apt update
sudo apt install firefox

⚠️ Optional: Enable Unattended Upgrades

Since the package comes from a PPA unattended-upgrades will not upgrade it automatically, unless you enable this origin:

echo 'Unattended-Upgrade::Allowed-Origins:: "LP-PPA-mozillateam:${distro_codename}";' | sudo tee /etc/apt/apt.conf.d/51unattended-upgrades-firefox

Intro

Debian 9 Stretch was released as the latest stable version of the Linux Distribution: Debian. While it’s always possible to install Debian 9 fresh from scratch, it’s also possible to perform an in-place upgrade from Debian 8. The following post describes the necessary steps to do so.

For a incredibly thorough documentation of the process, I suggest you also read through the official release notes.

Notes:

• Upgrading to Debian 9 Stretch is only supported from Debian 8 Jessie. If you are running a version older than 8, you must first upgrade to 8 before working through this process.
• The upgrade involves a kernel update, so a reboot will be required toward the end of the process.
• It is strongly recommended that you have a full system backup or backup of any important data before proceeding with the upgrade, ensure that you have a plan to roll back. In the case of a virtual machine, take a snapshot before starting.

Performing the upgrade to Debian 9 Stretch

Before proceeding with the upgrade, please read through the list of issues to be aware of when upgrading to Stretch.

1. It is recommended that you have your Debian 8 Jessie installation completely up to date before starting, to do this run “apt-get update” followed by “apt-get upgrade” and install available updates.

root@debian8:~# apt-get update
root@debian8:~# apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

In this case all updates have been applied already, so it’s fine to proceed.

Edit the /etc/apt/sources.list file, my file is shown below. As you can see all of the lines are currently specifying “jessie”. Note that your mirror sources will likely be different which is fine.

deb http://ftp.ch.debian.org/debian/ jessie main
deb-src http://ftp.ch.debian.org/debian/ jessie main

deb http://security.debian.org/ jessie/updates main contrib
deb-src http://security.debian.org/ jessie/updates main contrib

# jessie-updates, previously known as 'volatile'
deb http://ftp.ch.debian.org/debian/ jessie-updates main contrib
deb-src http://ftp.ch.debian.org/debian/ jessie-updates main contrib

Change the instances of “jessie” to “stretch”, you can either do this manually, or automatically with the below sed command.

sed -i 's/jessie/stretch/g' /etc/apt/sources.list

You can either use “stretch” or “stable”, as Debian 9 Stretch is now the current stable version as of writing. However note that if you use stable instead of the specific release name, in future when Debian 10 is released that will be the stable version so you may upgrade to that unintentionally.

The recommended way to upgrade Debian is with the ‘apt-get’ command. First update the list of available packages with the below command, as we’ve just updated the sources.list file.

apt-get update

Use “apt list –upgradable” command to quickly see what will be installed, updated, and removed during the upgrade process without affecting the system.

apt list --upgradable

Sample Output:

unattended-upgrades/stable 0.93.1+nmu1 all [upgradable from:0.83.3.2+deb8u1]
util-linux/stable 2.29.2-1 amd64 [upgradable from: 2.25.2-6]
uuid-runtime/stable 2.29.2-1 amd64 [upgradable from: 2.25.2-6]
vim/stable 2:8.0.0197-4 amd64 [upgradable from: 2:7.4.488-7+deb8u3]
vim-common/stable 2:8.0.0197-4 amd64 [upgradable from: 2:7.4.488-7+deb8u3]
vim-runtime/stable 2:8.0.0197-4 all [upgradable from: 2:7.4.488-7+deb8u3]
vim-tiny/stable 2:8.0.0197-4 amd64 [upgradable from: 2:7.4.488-7+deb8u3]

Now that the list of available packages has been updated from the mirror, run the below command to perform a minimal upgrade.

apt-get upgrade

This is known as a minimal system upgrade as it only upgrades packages that can be upgraded without needing any other packages to be removed or installed, so it’s a safe place to start. This upgraded 932 packages requiring 412MB on my system.

Now you’re ready to do the complete system upgrade, this will upgrade to the latest available version for all packages installed.

apt-get dist-upgrade

Ensure that you have enough free disk space to complete the operation, in my case it notes that afterwards 1,048MB of additional disk space will be used with 639 package upgrades and 479 newly installed packages.

During the distribution upgrade, services installed on your system needs to be restarted after up gradation of each service packages (ex. Apache, NTP) which may cause you the service interruptions. You can choose to restart automatically during upgrade or manually after the upgrade. Here, I opted to do “an automatic restart of services during the OS upgrade“.

Verify upgrade:

Reboot your machine after the distribution upgrade.

reboot

Verify the current version of Debian operating system.

lsb_release -a

Distributor ID: Debian
Description: Debian GNU/Linux 9.0 (stretch)
Release: 9.0
Codename: stretch

A large number of companies use “security” products to inspect HTTPS traffic for detecting malware and prevent other types of attacks. However, they might inadvertently make their user’s more susceptible to man-in-the-middle attacks by  decrypting and re-encrypting HTTPS connections.

The U.S. Computer Emergency Readiness Team (US-CERT) warns in an advisory that HTTPS inspection products don’t mirror the security attributes of the original HTTPS connections between the client and the server (Mirror: HTTPS Interception Weakens TLS Security | US-CERT).

HTTPS inspection is deployed in companies for checking the encrypted traffic coming from an HTTPS website to make sure it does not contain any malware or any other type of attacks. It basically performs a decryption and re-encryption of the client’s connection to an HTTPS server. The “security” products (proxy, web-gateway, firewall etc.) establish the connection on the client’s behalf by first decrypting the client’s HTTPS connection and re-encrypting the traffic sent to the HTTPS server. The client is served with a different, locally generated certificate by the security product which essentially perform a man-in-the-middle attack.

In some enterprise environments, an HTTPS connection may even be intercepted and re-encrypted multiple times. For example, at the network perimeter by a security gateway product and later, on the endpoint by a client’s antivirus program which needs to inspect the traffic for malware.

The problem revolves around the fact that the client’s browser no longer validates the real certificate issued by the server because its replaced with a locally generated certificate from the security product. In return, the task of validating the certificate now falls to the intercepting proxy.

According to the published advisory, those security products are evidently pretty bad at validating server certificates. An investigation conducted by researches from Google, Mozilla, Cloudfare, and multiple Universities states that the intercepted connections use weaker cryptographic algorithms (Source: interception-ndss17). The security products even advertise support for known-broken encryption ciphers that would allow an active man-in-the-middle attack by intercepting and downgrading a connection in order to decrypt it.

The analysis by the researches found that at least 32 percent of connections to e-comerce sites and 54 percent of Cloudflare HTTPS connections, which were intercepted, became less secure than they would have been if the user had connected directly to the server.

Browser makers had a long time to properly unterstand the quirks of TLS connections and certificate validation. Therefore, there is no better client-side implementation of TLS, the protocol used for encrypting HTTPS connection, than the one found in modern browsers.
In comparison, security product vendors use outdated, customised TLS libraries where they even back-port new protocol features. Re-implementing those features found in newer libraries makes them susceptible to serious vulnerabilities.

Furthermore, the US-CERT points out another widespread problem that many products intercepting HTTPS don’t properly validate the certificate chain presented by servers. Certificate-chain verification errors are infrequently forwarded to the client, leading the client to believe that operations were performed with the correct server.

The BadSSL website allows organisations and even employees to check if their HTTPS inspection products improperly validate certificates or allow for insecure ciphers. The client test from Qualys SSL Labs also provides checks for some known TLS vulnerabitiles and weakenesses.