I have been thinking about self-hosting my personal photos on my linux server. After the recent backdoor was detected I’m more hesitant to do so especially because i’m no security expert and don’t have the time and knowledge to audit my server. All I’ve done so far is disabling password logins and changing the ssh port. I’m wondering if there are more backdoors and if new ones are made I can’t respond in time. Appreciate your thoughts on this for an ordinary user.
You must log in or register to comment.
“We don’t” is the short answer. It’s unfortunate, but true.
Self hosting personal photos doesn’t generally require opening anything up to the internet, so most backdoors would not be accessible by anyone but you.
Or someone who has penetrated your network.
Of which the chances are slim to none for 99% of people simply because they aren’t interesting enough to be a target beyond phishing, scans, and broad attacks.
How do you know there isn’t a logic bug that spills server secrets through an uninitialized buffer? How do you know there isn’t an enterprise login token signing key that accidentally works for any account in-or-out of that enterprise (hard mode: logging costs more than your org makes all year)? How do you know that your processor doesn’t leak information across security contexts? How do you know that your NAS appliance doesn’t have a master login?
This was a really, really close one that was averted by two things. A total fucking nerd looked way too hard into a trivial performance problem, and saw something a bit hinky. And, just as importantly, the systemd devs had no idea that anything was going on, but somebody got an itchy feeling about the size of systemd’s dependencies and decided to clean it up. This completely blew up the attacker’s timetable. Jia Tan had to ship too fast, with code that wasn’t quite bulletproof (5.6.0 is what was detected, 5.6.1 would have gotten away with it).
In the coming weeks, you will know if this attacker recycled any techniques in other attacks. People have furiously ripped this attack apart, and are on the hunt for anything else like it out there. If Jia has other naughty projects out here and didn’t make them 100% from scratch, everything is going to get burned.
I think the best assurance is - even spies have to obey certain realities about what they do. Developing this backdoor costs money and manpower (but we don’t care about the money, we can just print more lol). If you’re a spy, you want to know somebody else’s secrets. But what you really want, what makes those secrets really valuable, is if the other guy thinks that their secret is still a secret. You can use this tool too much, and at some point it’s going to “break”. It’s going to get caught in the act, or somebody is going to connect enough dots to realize that their software is acting wrong, or some other spying-operational failure. Unlike any other piece of software, this espionage software wears out. If you keep on using it until it “breaks”, you don’t just lose the ability to steal future secrets. Anybody that you already stole secrets from gets to find out that “their secrets are no longer secret”, too.
Anyways, I think that the “I know, and you don’t know that I know” aspect of espionage is one of those things that makes spooks, even when they have a God Exploit, be very cautious about where they use it. So, this isn’t the sort of thing that you’re likely to see.
What you will see is the “commercial” world of cyberattacks, which is just an endless deluge of cryptolockers until the end of time.
You don’t. Hackers often exploit things like this for ages before they are found. Every bit of non simple software also has bugs.
But chances are you won’t be the target.
Just keep everything updated and you should be alright.
And implement least privilege and automatic updates
That’s the neat part, we don’t!
…but, we at least can have a shot of finding them.
In the meantime, I’d advise you to keep an eye out and maybe look into threat models. As people said in this thread already, bad actors probably don’t care about your personal photos.
Unless OP is a celebrity or politician. Or knows they have an enemy with the resources to find and exploit potential backdoors.
I would say you can’t, but if you are using open source software, then somebody can and will find them eventually and they will be patched. Unlike with closed source software, you will never know if it has a backdoor or not. This whole episode shows both the problems with open source, being lack of funding for security audits, and the beauty of open source, being that eventually it will be detected and removed.
The main solace you can take is how quickly xz was caught: there is a lot of diverse scrutiny on it.
Hmm, not really. It’s only because it nerd-sniped someone who was trying to do something completely unrelated that this came to light. If that person has been less dedicated or less skilled we’d still probably be in the dark.
Call me names… But sometimes the story has far more branched backstories than they actually shed into light.
Trust nobody, not even yourself.
The thing is there are a few thousand of those people
Maybe millions of potential eyes, but all of them are looking at other things! Heartbleed existed for two years before being noticed, and OpenSSL must have enormously more scrutiny than small projects like xz.
I am very pro open source and this investigation would’ve been virtually impossible on Windows or Mac, but the many-eyes argument always struck me as more theoretical/optimistic than realistic.
Heartbleed existed for two years before being noticed
That’s a different scenario. That was an inadvertently introduced bug, not a deliberately installed backdoor. So the bad guys didn’t have two years to exploit it because they didn’t know about it either.
It’s also not new that very old bugs get discovered. Just a few years ago a 24 year old bug was discovered in the Linux kernel.
And are bugs harder to find than carefully hidden backdoors? No-one noticed the code being added and if it hadn’t have had a performance penalty then it probably wouldn’t have been discovered for a very long time, if ever.
The flip side to open-source is that bad actors could have reviewed the code, discovered Heartbleed and been quietly exploiting it without anyone knowing. Government agencies and criminal groups are known to horde zero-days.
We can’t know. If we would know, those weren’t undetected backdoors at all. It’s not possible to know something you don’t know. So the question in itself is a paradox. :D The question is not if there are backdoors, but if the most critical software is infected? At least what I ask myself.
Do you backups man, do not install too many stuff, do not trust everyone, use multiple mail accounts and passwords and 2 factor authentication. We can only try to minimize the effects of when something horrible happens. Maybe support the projects you like, so that more people can help and have more eyes on it. Governments and corporations with money could do that as well, if they care.
you don’t and will never will. I would recommend reading a lecture by Ken Thompson the co-creator of Unix for more details on this https://www.cs.cmu.edu/~rdriley/487/papers/Thompson_1984_ReflectionsonTrustingTrust.pdf
Cheeky answer:
Actual answer:
Theoretically anyway, open source software’s guarantee of “no backdoor” is that the code is auditable, and you could study it and know if it has any holes and where. Of course, that presumes that you have the knowledge AND time to actually go and study thousands of lines of code. Unrealistic.
Slightly less guaranteed but still good enough to calm my mind, is the idea that there is a whole-ass community of people who do know their shit and who are constantly checking this.Do note that like. Closed source software is known to be backdoored, only, the backdoors are mostly meant for either the owners of the software (check the fine print folks) or worse, the governments.
The biggest thing that you should note is that: It is unlikely that you (or I or most of the people here) are interesting enough that anyone will actually exploit those vulnerabilities to personally fuck you over. Your photos aren’t interesting enough except as part of a mass database (which is why Google/Facebook want them). Same for your personal work data and shit.
Unless those backdoors could be used to turn your machine into a zombie for some money-making scheme (crypto or whatever) OR you’re connected to people in power OR you personally piss off someone who is a hacker – it is very unlikely you’ll get screwed over due to those vulnerabilities :P
Just a point to add: this backdoor was (likely) planned years in advance; it took ONE guy a couple weeks (after the malicious code was released) to find it because he had nothing else going on that evening.
I’m relatively confident that the FOSS community has enough of that type of person that if there are more incidents like this one, there’s a decent chance it’ll be found quickly, especially now that this has happened and gotten so much attention.
Even better: there are also backdoors in closed-source software that will never be found. There may be fewer backdoors inserted, but the ones that get in there are far more likely to stay undiscovered.
deleted by creator
We don’t. That’s why we use multiple layers of security. For example keeping all services accessible only via VPN and using a major OS that a lot of production workloads depend on such as Debian, Ubuntu LTS or any of the RHEL copycats. This is a huge plus of the free tier of Ubuntu Pro BTW. It’s commercial level security support for $0. Using any of these OSes means that the time between a vulnerability being discovered, patched and deployed is as short as possible. Of course you have to have automatic security updates turned on,
unattended-upgradesin Debian-speak.if you are self hosting and enjoy over-engineering systems… VLANS, ACLs between subnets and IDS/IPS should be part of.your thinking. separate things into zones of vulnerability / least-privilege and maintain that separation with an iron fist. this is a great rabbit hole to fall down if you have the time. however, given a skilled adversary with enough time and money, any network can be infiltrated eventually. the idea is to try to minimize the exposure when it happens.
if the above is not a part of your daily thinking, then don’t worry about it too much. use a production OS like Debian stable, don’t expose ports to the public internet and only allow systems that should initiate communication to the internet to actually do so (preferably only on their well known protocol ports - if possible).
We dont.
This was likely a state-sponsored attack. If your SSH isn’t exposed to the internet this probably wouldn’t have effected you. Also most people run stable distros like Debian on their server, and this particular vulnerability never made it to the stable branch. I would guess that most of the computers you have ever used have backdoors. Even if you run Linux (which may itself have some) you might still have a proprietary UEFI on your motherboard. Something like xz wouldn’t effect you because no government really cares what’s on your server. Smaller attacks can be avoided through common sense. Some people will expose services that require zero authentication to the internet. Follow basic best practices and you will probably be fine.
Edit: Also remember, google photos once flagged a picture of a child that the child’s father had taken for medical reasons as abuse, so self-hosted may not be completely private or secure, but it’s better than the alternative.
