…without snark or jumping down my throat. I genuinely want to know why it’s so unsafe.
I’m running a Synology DS920+, with my DSM login exposed through a Cloudflare tunnel. I have 2FA enabled, Synology firewall enabled with these rules in place. I also have this IP blocklist enabled.
After all of this, how would someone be able to break in via the DSM login?
NAS vendors aren’t known for understanding security. Opening ssh to the world is no problem, because ssh is everywhere, it’s constantly attacked, and half the world would know if an exploitable vulnerability was found.
If NAS vendor ABC has a vulnerability in the login code written by a programmer who hasn’t done much more than CSS, it would surprise nobody, and you wouldn’t hear about it on any IT news sites. It would just be exploited until all the machines were exploited or until they’re all patched.
It really is a world of difference between something known and secure and some random login page.
Opening ssh to the world is no problem
That seems to go against the general consensus… Why is everyone/everything online telling me to either disable SSH entirely, or change the SSH port to something incredibly obscure (and even that’s not safe)?
Because they’re being silly. There is no other public facing service more secure than a relatively modern OpenSSH.
In some instances, yes, it’s best to disable the ssh that comes with whatever NAS OS you’re running, because they often ship old code and don’t care about updates and security.
But if you’re running a relatively up to date OpenSSH and you’re using keys, not passwords, then you are as secure as you can reasonably be. There’s no math suggesting otherwise. Moving to a different port will reduce the frequency of attack, but that will have zero impact on the possibility of intrusion.
Put it this way: if relatively recent OpenSSH has a remotely exploitable vulnerability, you’ll see it on the news on TV. You’ll see it and hear about it literally everywhere. The world will stop for 24 hours and there will be widespread panic. You’ll know.
If your NAS has an exploit, you might read about it on The Register a few months later.
If your DS920+ is completely inaccessible to outside your network except for the Cloudflare tunnel, then the Synology firewall and IP blocklist aren’t going to do squat for you since all connections will appear to originate from either inside your network or from Cloudflare. So you’re 100% dependent on Cloudflare to keep bad actors out.
I’m not familiar with Cloudflare but the impression I had from looking at it was that you can decide which authenticated Cloudflare users can access your tunnel. So it’s a matter of credential management. Supposing some bad actor gets your credentials, they would then be able to access the entirety of your NAS, and you’re now hoping that there isn’t some undiscovered or unpatched security hole that they can use.
All software has bugs. Sometimes bugs let you do things you weren’t intended to be able to do (e.g. access data on a NAS without knowing the login password). Your NAS might have a bug that hasn’t been discovered (or publicized yet) or hasn’t been fixed yet.
If you put your NAS on the internet, you give “bad guys” am opportunity to exploit those bugs to get your data or to use your NAS as a jumping off spot to attack other things inside your home network.
Security for systems are designed for their target use case. The NAS login page was designed to be easily usable and assumed to only live within a private network. By opening to the internet you are opening it up to be targeted in a way the designers may not have accounted for.
Surprised no one posted this, the web and cyber threat look like that : https://livethreatmap.radware.com/
I wouldn’t trust Synology on that aspect, better have an entry over VPN.
