…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.
Well said!
Here’s the way I think of it. Imagine you live in a house at the end of a long street. Your front door is the login page to your Synology. All the measures you’ve put in place (cloudlfare, ip blocklists, firewall) are the equivalent of putting up a guard booth/gate at the end of your driveway that only allows cars with a license plate of a specific state.
You haven’t made yourself significantly more secure, just lined the traffic up in a more organized fashion. You are still trusting the people that made your door lock to not be vulnerable.
Yes, it’s easier to access vs having a big metal gate that only you have the code to open (VPN) in front of your house. But why open yourself up to a single point of failure?
Here’s just one recent example of an attacker being able to bypass the authentication on a synology. All the things you have implemented wouldn’t prevent a single person in the internet from using this exploit. https://www.zerodayinitiative.com/advisories/ZDI-23-660/
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.
Don’t expose the login to internet. Use twingate, headscale/tailscale. It’s super easy to setup and use zero trust network access.
Speaking as someone who decided to “just be a consumer and trust that my NAS manufacturer had appropriately hardened the login interface”, and was using 2FA, and subsequently fell victim to a ransomware attack:
Do not expose any port on your NAS to the internet.
If you really want it available to you when you’re away from home, set up a VPN using a separate device as the VPN server.
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.
Not true, cloudflare will forward the real IP in the headers, and if your nas is correctly configured (trusts the forwarded header), it can block the source based on IP.
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.
if you must, have you looked at the azure application proxy? if you configure it properly it should work from the outside world, and still remain private. This does put a lost of trust into azure, and your tenant’s users not getting broken into.
If you open your login page to internet without security, someone one day will have a field trip inside your NAS files and will find all your “i know what you did last summer” photos.
I do have DS423+ and i am too using Cloudfare tunnel to access it from anywhere.
My CF Tunnel setup done like this:
Domain: nas.example.com points to http://1.2.3.4: and i have 2 access rules added.
One of these rules NEEDS to match otherwise - “You Shell Not Pass”
#1: Public IP needs to be matched as my public IP
#2: Person who wants to login needs to authenticate via Google Authentication. Google authentication needs to match test1@gmail.com or test2@gmail.comWhile i am at home, i use nas.example.com to access my nas instead of using its local IP and cloudflare allows access with no questions asked.
While i am outside my home network i get asked to authenticate via google and gain access this way.+CF Tunnel adds https automatically for me.
I don’t use any firewall setup or any other rules inside NAS.
Millions of hostile computers are cruising the internet looking for literally anything that can be exploited. Do not give them an opportunity by exposing a login page unnecessarily.
https://www.synology.com/en-us/security/advisory
https://www.cvedetails.com/vulnerability-list/vendor_id-11138/Synology.html
You can look through all known issues.
But don’t get me wrong, I’m glad they provide the information!
Don’t know how much a Cloudflare tunnel protects you. Maybe it’s only security by obscurity.
Because you’re going to be hit by the next of the countless pre-authentication vulnerabilities that constantly pop up for appliance’s like yours.
All your security measure will do absolutely nothing in that case.
I don’t get why you don’t just set up a VPN? It isn’t more complicated than what you did, and offers far superior protection. And for 99% of use cases, you don’t loose any functionality either.
NAS appliances aren’t known for their login security
See my other comment, but the basic problem is you are only putting one layer of protection if you expose directly to the Internet. If there is a vulnerability in NAS, then bots can exploit just that layer and get in.
If you have tunnel/VPN then NAS, they have to have a vulnerability in the VPN, then also be able to use the VPN to exploit the NAS (or some other device on the VPN).
Add another layer, like IP limitations on the tunnel, then you have to have 3 exploits. Etc…
Synology sells based on convenience of features, and good enough security as a second thought. VPN or tunnel software exists to provide security. So you want to mix the focus and the providers to minimize chance any one provider or mistake will let you get hacked.
The biggest risk for a typical home lab is from bot scanners and not targeted attacks, so they are unlikely to target a connection with more than one layer as there are many, many simpler targets.