Ubuntu Security Podcast

Episode 166


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Overview

From the deep-web to encryption we decode more cybersecurity buzzwords,

plus we cover security updates for Squid, Vim, the Linux kernel, curl and
more.

This week in Ubuntu Security Updates

16 unique CVEs addressed

[USN-5491-1] Squid vulnerability [00:29]
  • 1 CVEs addressed in Bionic (18.04 LTS), Focal (20.04 LTS), Impish (21.10), Jammy (22.04 LTS)
    • CVE-2021-46784
    • Possible DoS when handling Gopher protocol (early alternative to HTTP)
    • [USN-5487-2, USN-5487-3] Apache HTTP Server regression [01:09]
      • 7 CVEs addressed in Trusty ESM (14.04 ESM), Xenial ESM (16.04 ESM), Bionic (18.04 LTS)
        • CVE-2022-31813
        • CVE-2022-30556
        • CVE-2022-30522
        • CVE-2022-29404
        • CVE-2022-28615
        • CVE-2022-28614
        • CVE-2022-26377
        • Episode 165
        • [USN-5492-1] Vim vulnerability [01:25]
          • 1 CVEs addressed in Xenial ESM (16.04 ESM)
            • CVE-2022-2042
            • UAF which could be triggered when opening and then searching through a
            • crafted file -> crash -> DoS / RCE
              [USN-5493-1] Linux kernel vulnerability [01:54]
              • 1 CVEs addressed in Xenial ESM (16.04 ESM), Bionic (18.04 LTS), Focal (20.04 LTS), Impish (21.10)
                • CVE-2022-28388
                • GA kernels (5.13 for 21.10, 5.4 for 20.04 LTS, 4.15 for 18.04 LTS and 4.15 HWE for 16.04 ESM)
                • 8 Devices USB2CAN driver - double-free in error scenario - local attacker
                • could use a crafted device to trigger -> DoS
                  [USN-5494-1] SpiderMonkey JavaScript Library vulnerabilities [02:47]
                  • 2 CVEs addressed in Jammy (22.04 LTS)
                    • CVE-2022-31740
                    • CVE-2022-28285
                    • aka libmozjs-91 - 91.10
                    • Jeremy Bicha from Ubuntu Desktop team
                    • Not easy to identify security issues in mozjs - Jeremy had to search
                    • through the list of commits in mozjs and search for bug numbers in
                      upsteam mozilla bug tracker which were then referenced by the various
                      Mozilla security advisories
                    • also incidentally fixes a FTBFS with vendored ICU (test failure during
                    • build)
                      [USN-5495-1] curl vulnerabilities [04:19]
                      • 4 CVEs addressed in Bionic (18.04 LTS), Focal (20.04 LTS), Impish (21.10), Jammy (22.04 LTS)
                        • CVE-2022-32208
                        • CVE-2022-32207
                        • CVE-2022-32206
                        • CVE-2022-32205
                        • All 4 issues identified by Harry Sintonen
                          • Mishandling of Set-Cookies header - crash -> DoS
                          • mishandling of chained HTTP compression algorithms - a server which
                          • compressed a response with a huge number of repeated steps could result
                            in a malloc bomb during decompression -> OOM -> DoS
                          • Failed to properly set permissions when downloading cookies or other
                          • files so they could possibly by read by other users - can mitigate by
                            making sure you use a strict umask locally (but that can have other
                            unintended consequences for other applications)
                          • FTP xfer secured by krb5 - fails to properly verify messages - could
                          • then have a MiTM inject data etc
                            Decoding cybersecurity buzzwords (part 2) [06:07]
                            • From encryption to the deep/dark web Camila continues the journey into
                            • demystifying some more of the most popular buzzwords in cybersecurity
                              Transcript

                              Hello listener! Welcome to part 2 of our cyber security buzzword series!

                              Last episode we talked about ransomwares, botnets and phishing attacks!
                              Let’s keep the bees happy and continue on in this buzzing journey of better
                              understanding what is the meaning behind the word and turning the
                              “bzzzzzzzzzz” into an “aaaaah, I see” instead! 039 If you haven’t listened
                              to the last episode I highly recommend you do it before you proceed with
                              this one, but hey, that is your choice. I don’t want to take too long with
                              this introduction, so, for those who are already in for this ride, without
                              further ado, let’s jump in! Our first word of today and the fourth
                              overall…we’ve talked about it before, and we are talking about it now
                              once again… buzzword #4 is the one and only firewall! If you listened to
                              the episodes involving the Ubuntu hardening topic, you already know that
                              our dearest friend firewall is one way to keep your network safe because it
                              allows you to filter and possibly block incoming and outgoing traffic in
                              your network. Through use of a firewall you can define that users in your
                              network can’t access a specific website, or you can keep connections coming
                              from a specific IP address from ever being established with these same
                              users. It’s an important job the one done by a firewall, however, it is not
                              100% hacker proof. A firewall does what it needs to do well, but it won’t
                              save you from yourself, for example, if you decide to become the victim of
                              every phishing campaign happening out there. So…do you see that buzzword
                              right there: “phishing”? That is why I recommended you listen to the last
                              episode, because I explain what is phishing THERE. Moving on, if e-mail
                              service is allowed by the firewall, a hacker can try to get to the network
                              through it, and in that case, my friend, you are the weakest link, as said
                              hacker is expecting you to make the mistake that will allow them passage
                              when the firewall will not do so through other ports or services in the
                              network. Don’t expect a wall to protect your network if your staff is
                              handing out keys to the building’s backdoor to anyone that mentions that
                              they work there!!! I am adding firewalls here on this list because ever
                              since the dawn of time…or at least the dawn of my time…I see the word
                              firewall being thrown around in television shows, in presentations that
                              want to nudge cyber security a little bit, and even on the thoughts of
                              people who are wondering “How did I get infected with malware, I have a
                              firewall!!!”. So…yeah. Unfortunately the buzzword became a universal term
                              used to describe all software and defensive techniques, even if they are
                              not all the same. To make an analogy, a firewall is one fruit amongst the
                              huge selection of different fruits that exist in this beautiful world, but
                              people insist on calling all fruits ‘firewalls’. I am sure you can imagine
                              a situation where I give you a lime and call it an apple, and I am sure
                              that in your imagination you are not too pleased about the result once you
                              bite into that fruit expecting one thing and instead getting another. You
                              might feel a little ‘sour’ should I decide to do such a thing. Haha, get
                              it? Bad jokes aside, it’s important to understand what a firewall really is
                              and what it can actually do for you in terms of protecting your
                              network. Not all attacks are the same, so not all attacks will be stopped
                              by a firewall. If you go beyond the buzzword and beyond the beautiful wall
                              and fire icon - which at this point could be called a buzzicon - you start
                              to actually build a defense strategy that makes sense and is efficient for
                              your network, one that will include a firewall, BUT will not expect it to
                              defend the network, cook and wash your clothes all at the same
                              time. Therefore, the next time your hear someone in a show mentioning that
                              they have breached 50% of the firewall, remember your training, remember
                              what a firewall actually is, and remember that if you are able to bypass
                              the firewall, you either did it 100% or you simply didn’t, and then relax
                              and laugh a little, because you used your knowledge to actually build a
                              defense strategy that even if an attacker bypasses the firewall by 100%,
                              you are able to prevent an attack from actually being successful with the
                              help of your other layers of defense. You fought valiantly firewall friend,
                              but not all threats are avoidable by you, and we know that now. We also
                              know now that movie security in movie networks are probably awful, because
                              they seem to only use a firewall to defend very important data, and the
                              firewall is most likely broken, being only 50% bypassed and all…geez, get a
                              grip, hollywood, or hacking might become TOO easy for those imaginary
                              hackers.

                              Buzzword #5: encryption…encrypting…encrypted…encrypt. This buzzword

                              is also one that I think can be considered a long-living buzzword. Data
                              encryption suffers from the same problem as firewalls in the sense that
                              people see it as a solution to all of their problems. Oh…and movies also
                              like to use the word a lot. “If my data is encrypted it is completely
                              safe”. Right? Wrong. What is encryption then, and what purpose does it
                              serve? When you encrypt your data, you are actually just encoding
                              it. Transforming it in such a way that whatever information is actually
                              imbued within it cannot be extracted because the data no longer represents
                              something that can be understood by a potential snooper of that data. One
                              encrypted character a day keeps the snooper away, or at least that is the
                              goal anyway. The main purpose of encryption is to maintain data
                              confidentiality, or, in other words, to prevent an unauthorized party from
                              getting access to the data that is going to be encrypted. Therefore,
                              encryption is a technique that will serve the purpose of encoding data in
                              such a way that it loses its meaning to whoever is not authorized to know
                              it. Who are the ones authorized? Those that have the decryption key…and
                              if that key is stolen or shared with someone it shouldn’t be…well then
                              you can say goodbye to your expected confidentiality, as this new someone
                              can now decode the data and interpret it as you would. I guess what annoys
                              me a little bit about this buzzword is the fact that it is used to make
                              people feel completely safe even when the situation does not necessarily
                              guarantee this. The most simple example I can think of is VPNs. I see
                              advertisements for those all the time, and in these advertisements people
                              mention how VPNs will help you stay safe from hackers when you are browsing
                              online…and that is not completely true. It depends on what the hacker is
                              doing. If a hacker is trying to track you and figure out what you are doing
                              in the internet, that is, they are trying to snoop on your browsing
                              activities, then yes, a VPN, which will help you mask your tracks by adding
                              a layer of encryption to your traffic and acting as a middle man in your
                              communication with your destination, will indeed protect you. Think of it
                              as sending an encrypted letter to an intermediary courier. Only you and the
                              courier know the decryption key and so anyone that tries to intercept the
                              letter and does not have this key will be unable to do anything about
                              it. They don’t know who is the actual destination of the letter nor do they
                              know what is the purpose of the letter, all they know is that the courier
                              will receive it and send it to the actual destination. Encryption keeps
                              your communication confidential. Once it gets to the courier, the courier
                              decrypts it and then sends it to the actual destination and your snooper
                              can’t know it is from you because the courier is also sending and receiving
                              data from a bunch of people, and that courier has promised secrecy to you,
                              meaning, it promised it won’t tell others which is your letter. Anyway, now
                              think about the situation where you willingly decide to access a malicious
                              website through a VPN. There is no encryption that will save you from your
                              bad choices here. An encrypted conversation with an attacker is still a
                              conversation with an attacker, and an encrypted malware sent to you through
                              your VPN tunnel will still execute in your machine should you tell it
                              to. So once again I tell you, use encryption but know its purpose! It is
                              not because a website is HTTPS, or, in other words, it is not because a
                              website has that little lock in the top left corner, that you are protected
                              from all evil lurking on the internet. All it means is that data you send
                              to that website’s server will be sent to it encrypted. This in turn means
                              that your login credentials won’t be out in the open, being sent in clear
                              text through the network, free to be accessed by anyone that chooses to
                              sniff the data in any point of the path from source to destination. They
                              will be encrypted, and whoever comes across this data in transit won’t be
                              able to know the true contents unless they have the decryption key, which
                              is shared between you and the server only. However, you can decide to send
                              encrypted credentials to an attacker as well. Malicious websites can be
                              HTTPS. In fact, attackers take advantage of the fact that people blindly
                              trust HTTPS websites because they are “encrypted” and make fake HTTPS bank
                              pages in order to steal credentials. Phishing attacks, remember those? So
                              here we have a situation where the buzz in the word is being harmful for
                              those that don’t actually try to understand the meaning behind it. When you
                              want to make sure a website is safe, not only check for the tiny lock in
                              the top-left corner of the browser, also do check if the website’s
                              certificate actually identifies that page as being authentic, as being
                              owned and provided by the entity that you believe it to be. So…yeah. I
                              guess final thoughts on this once again are: encryption is fine when you
                              don’t forget to combine….it with other security measures. I wanted to make
                              a cool rhyme, but that didn’t work out. Oh well…onto the next buzzword!

                              Buzzword #6: the deep web. Ooooh, spooky! Once again we are in “buzzword

                              because of the movies” territory. Hacker, firewall, encrypted data, network
                              breach, deep web. Oh, and a guy wearing a black hoodie. The cliché buzzword
                              we see getting thrown around every time someone wants to talk about cyber
                              security and sound mysterious while doing it. I mean…I can’t really blame
                              them, as it is human nature to enjoy mysteries and to want to solve
                              them. So, I guess if you are in the entertainment industry, throwing out
                              the word “deep web” around is indeed one of the ways to go. However, if you
                              are an IT professional, blindly trusting that what you see in movies is how
                              things actually work is definitely not. Does the deep web contain
                              mysterious websites and crazy mind bending information? Yes. Is it a
                              blackhole where only the most courageous may enter and the most bizarre may
                              stay? No. No! A bunch of the websites you have in the surface web also
                              exist in the deep web! If you want, you can do your regular browsing but
                              using the roads - let’s call them that for now - of the deep web
                              instead. All you have to do is download the software tool that will allow
                              you to access it. The most well known tool to do so is the Tor browser,
                              which will give you access to the Tor network, where lot’s of deep web
                              websites are hosted. So let’s talk a little bit about the Tor network and
                              try to understand what is the oh-so-mysterious deep web and why you can’t
                              access it by simply typing “Take me to the deep web” on a search engine in
                              your regular browser. Think about the Internet as being the entire
                              planet. Earth as you know it. Everyone and everything we know and can
                              access is inside the planet…and for the smarty pants that will try to say
                              “but what about space travel???”, don’t be a downer and destroy my
                              analogy. Use your imagination and PRETEND like all we know is inside the
                              planet only, which is the ONLY thing we have access to. The planet is like
                              the entire Internet. Now imagine all of the roads on the planet. You can
                              drive through them and go anywhere you want, the same way your data can
                              flow through the Internet and reach several destinations which will provide
                              you with services such as web browsing and e-mail sending. Consider now,
                              however, that a group of servers, or, to stick to the analogy, a group of
                              destinations for road trips, decide to bundle together and create their own
                              underground secret routes and make themselves and their services accessible
                              only to travelers which use those secret routes. The regular roads that
                              would lead you to them are destroyed and there are now a few single regular
                              roads that lead to the entry-points of the underground tunnels. Anyone can
                              enter the underground tunnels if they wish to and use the tunnels to reach
                              those “secret” destinations, as can anyone download a Tor browser and find
                              websites which are deb web or even darknet services. However, if you want
                              to reach your destination you must use the tunnel, and you can no longer
                              use maps to reach this destination, since in the underground tunnels they
                              provide you with no maps as they do in the surface roads. No maps so that
                              the destinations remain well hidden within this secret underground road
                              network, and so that they can “change their location” or “stop existing”
                              whenever they wish to do so. No records means no tracking. When entering
                              the underground tunnels you set up three intermediate tunnel only
                              destinations that will help you reach your desired end point, let’s
                              consider those toll booths. The first one is where you will always stop at
                              the beginning of your journey, the second one will connect you to the last
                              one, which in turn will be the one that will finally tell you which road to
                              follow to access the destination which will provide you with the service
                              you wish to access. Think now that these intermediate points recognize you
                              by your car color. A very specific color you and each toll booth attendant
                              have previously decided on, the moment you knew they would be your
                              intermediate stops. So the first point recognizes a red car, the second a
                              blue car, and the last a green car. I am using simple colors here, but to
                              amuse your own imagination, you can think of it as a very specific shade of
                              red that cannot be replicated by anyone else, meaning it will identify you
                              uniquely to that specific toll booth. Same goes to the blue and to the
                              green. Before passing through your underground toll booths you paint your
                              car green, then blue and then red. When you get to the first mark, the toll
                              booth guard recognizes the red hue of your car and identifies you as a
                              valid passenger. It removes the red hue and you tell it your next toll
                              booth stop. It forwards you in that direction, meaning it shows you the way
                              to the blue toll booth. You go to the blue tollbooth and the same thing
                              happens. It recognizes the blue hue, removes it and sees that you are going
                              to the green toll booth, and it directs you there. Finally, when you reach
                              green they do the same, but they finally send you to your final
                              destination. Notice that this allows you to stay anonymous because you got
                              in in a red car and got to your destination in a green colored car. The red
                              toll booth does not know your final tollbooth was green, knowing only you
                              went to blue, and the green does not know your starting point was red,
                              knowing only you came from blue. Blue does not know your starting point nor
                              you final destination, knowing only that you came from red and left for
                              green. Going back to that final destination: your final destination can be
                              outside of the underground tunnels and back on the main roads. You used the
                              underground tunnels just so that people who see you get in through the
                              tunnels in a red car don’t follow you and don’t know where you got
                              out. Your final destination, however, can also be inside the tunnel
                              network. If that is the case, you will never go to the actual destination,
                              because underground tunnel services establish an intermediate rendezvous
                              point for communication and service offering instead of letting you reach
                              them at their actual location. Knowing the secret name of the service, you
                              are able to obtain information on what places are set as these rendezvous
                              points. So…leaving the analogy for a little bit…this is basically what
                              the Tor network is and what at least part of the deep web is. The Tor
                              network is an established network inside the internet. The secret
                              underground roads inside of the planet’s entire road network. It still uses
                              roads, meaning, it still uses IP addresses and establishes communication
                              between devices using regular means in layers under the application layer
                              itself. However, it defines a private communication method within the
                              public internet. Anyone can download a Tor browser and access Tor websites,
                              which would be part of the deep web websites, however, to do so, you need
                              to know the website’s address in the format that will be recognized in the
                              Tor network. Unlike the surface web where you register the mapping of your
                              website name and the IP address of the server that will host that website
                              in order for people to be able to find it without having to memorize a
                              complex number to do so - thank you DNS -, in the Tor network what you will
                              know is the name of the onion service and the location where this service
                              meets clients wishing to access it. Tor nodes, our toll booths, can then
                              route you to this destination, where you can introduce yourself to the
                              server and then set a rendezvous point which is where the rest of the
                              communication between you will actually happen. In the Tor network, it is
                              not as simple as the definition of an explicit mapping that says “oh, you
                              want to get to this place? Here is the address!”. Nope. Here, everything is
                              done covertly and secretly. You have a meeting place to define the
                              definitive meeting place. So maybe it is a little bit mysterious after
                              all. I’ll give the movies that. Of course you can use the Tor network, our
                              secret underground tunnels, to access a regular surface web website if you
                              want to. It is not necessary, but a lot of people do it because it allows
                              for anonymous browsing. Our underground tunnels won’t allow for
                              identification of who sent a message that is reaching a specific
                              destination, remember the whole car painting process and the colorful toll
                              booths? Well, in technical terms, Tor uses layers of encryption and
                              intermediate proxy nodes in order to stop someone snooping from knowing who
                              is the original sender of a message arriving at a certain
                              destination. ENCRYPTION being used to assist in keeping anonymity and to
                              maintain confidentiality of the data that is being transferred by whoever
                              is using the Tor network. So yeah…kind of a long explanation, but
                              demystifying it, this is what the deep web is: encryption, intermediary
                              nodes, regular websites, creepy websites, and lots of bureaucracy to get
                              you to your final destination. Oh, wait…that’s just part of it, since Tor
                              is only one of the many underground tunnel networks that exists out
                              there. There are others with different rules, different entry regulations
                              and different functionalities and purposes in general. I decided to tell
                              you about how the most famous one of these secret networks within the
                              network works so that you can get the genral iceberg idea of it. However,
                              lady Internet is a vast place, filled with opportunity to create and embed,
                              so secret networks which can not have their services accessed through the
                              regular WWW URL are plenty out there, all you need is the will and the
                              knowledge of the way to explore it! Oh, and the permission as well. I am
                              not condoning you committing a crime here.

                              Anyway, I think that is enough of me talking for one episode. Tune in for

                              next time where we will talk about our last three buzzwords for this
                              series, which I might add, are three giants…all of them suggested by my
                              Ubuntu Security Team peers of course! Feel free to share your thoughts on
                              today’s episode and buzzwords in any of our social media channels, I would
                              love to hear what you have to say about it! For now, I bid you all farewell
                              and until next time! Bye!

                              Get in contact
                              • #ubuntu-security on the Libera.Chat IRC network
                              • ubuntu-hardened mailing list
                              • Security section on discourse.ubuntu.com
                              • @ubuntu_sec on twitter
                              • ...more
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