8 ms·

Synology MFA Fails if Internet is down

60 points by alexfromapex 3y ago

WirelessGigabit 3y ago
I can think of many reasons not to use a Synology router, and this is one of them. Other ones: * Depending on your settings they broadcast an IPv6 DNS when they shouldn't. I told them about the bug and they scoffed. * Wrong setting when you DO broadcast an IPv6 DNS with just SLAAC. They send it via DHCPv6 without setting the right bits. * Setting up 2 networks with 2 domains, like iot.wirelessgigabit.com & home.wirelessgigabit.com does not work. They don't attach the domain to the the network. Last one wins. * No way of redirecting traffic, like all outgoing :53 to a port. All you can do is block which breaks things like a Google Mini. * No WireGuard VPN * No OIDC authentication. (DSM has it but for some arcane reason you need to join the domain before OIDC works...)
michael_michael 3y ago
MFA for my Synology failed recently because (I suspect) I let the drive go unused for a while and it lost sync with the time server. So all one time passwords my password manager generated were "wrong". Off in time by some unknown amount. No way to fix it, since I would need MFA to log in and fix it anyway. I had to reset the administrative UI and lose my user settings/admin preferences, but it did hang on to the data on the drives, luckily.
- antsar 3y ago
  Experienced this too. Having SSH access enabled on the Synology saved the day. There's no 2FA prompt on SSH, so you can SSH in and manually fix the time.
  - naasking 3y ago
    Old tricks are the best tricks!
  - olyjohn 3y ago
    Kinda defeats the whole point of MFA if you can just bypass it like that.
    - TrickardRixx 3y ago
      If the SSH key is password-protected, then SSH access is MFA.
      - doubled112 3y ago
        My SSH key is on a YubiKey. How many factors is that?
        eli 3y ago
        1 if it isn't password protected and 2 if it is
      - olyjohn 3y ago
        Not sure that's true... If the key gets compromised, having it password protected does nothing.
        password4321 3y ago
        > If the key gets compromised, having it password protected does nothing I apologize for my ignorance in advance: having a private key file password-protected does nothing? I guess I'm not understanding what you mean by "compromised"?
        olyjohn 3y ago
        Compromised, meaning someone has the key in an unprotected format, or they somehow got your password. Say someone manages to MITM you somehow and get your password to the file, or they manage to crack it, or phish it out of you. Then they can just take the key and use it freely to log into your things. With MFA, there's no way that any key can be used to log in as long as the other factor exists. If you have to push OK on your cell phone to log in for example, the key is useless without physical access to your phone. I'm not saying the password protection does nothing, it makes the key harder to crack but it's not another factor. It's simply an extension of the existing key. In other words, it's just a longer password.
blkhawk 3y ago
huh - normally there should be a set of "one use" codes for exactly this scenario.
- crazygringo 3y ago
  Yeah it's weird they don't: https://kb.synology.com/en-ca/DSM/help/DSM/SecureSignIn/2factor_authentication?version=7 https://kb.synology.com/en-ca/DSM/help/DSM/SecureSignIn/2fac... They support a backup e-mail address that it will send a verification code to if you lose your 2FA device. But, whoops -- that's not gonna work if it can't connect to the internet.
RedShift1 3y ago
MFA always feels like such a kludge... Do we really have no better ideas to solve this?
- whizzter 3y ago
  There's an RFC for a standard that I believe the Google Authenticator uses (and other authenticators also?). Basically (if I've understood it correctly), You get an random seed that you initiate the authenticator with, then for (each minute?) it combines the unix timestamp, the seed and calculate the time-based-one-time-password. So combining a user-specific password, the TOTP (whose seed is on an initiated device for the user) you have 2 factors that can be hard for an attacker to retrieve both of. https://datatracker.ietf.org/doc/html/rfc6238 https://datatracker.ietf.org/doc/html/rfc6238 (Kludgy? Maybe a bit but feels fairly secure in practice)
  - oldbbsnickname 3y ago
    HOTP (one-time) and TOTP are typically used in conjunction with one another. HOTP provide backup codes should client or server time be out of sync. https://www.rfc-editor.org/rfc/rfc4226 https://www.rfc-editor.org/rfc/rfc4226 FIDO2 with a hardware key source provides a much stronger and more secure guarantee than a 6 digit hash and an unencrypted symmetric secret stored in an app. https://fidoalliance.org/fido2/ https://fidoalliance.org/fido2/ Any and all 2FA approaches demand backup codes (and backup code management with confidentiality and durability) to protect against 2FA loss or inability of the 2FA to function. For example, there are some apps that insist on performing FIDO2 on a non-NFC platform. While I can use a Lightning to USB-C adapter to workaround this limitation, it's possible that I might not have it and would need some other 2FA "sufficient" mechanism. By the way, there is "HSM"-like passkey functionality embedded in most modern Apple and Samsung devices that doesn't require a USB token. This has the downside of not being a dedicated hardware token, so it cannot be physically isolated offline and requires an additional piece of software to act as a FIDO2 authenticator.
    - lll-o-lll 3y ago
      What sucks is that password’s don’t need to be so insecure. If you took WebAuthn and, instead of the private key, used one password, it’d be nearly as strong. Assuming that one password is sufficiently strong, and the password input could not be intercepted, and no one ever looked over your shoulder, or used a camera, and you never wrote it down somewhere others can find it, and you never typed it where someone had installed a key logger… Actually, let’s bring on the passkeys.
wiml 3y ago
tldr: TOTP doesn't work if one device doesn't know what time it is.
crazygringo 3y ago
Genuine question: does MFA conceptually make any sense for a device on your local network, accessed locally? I understand why you'd want it if trying to access your NAS from the internet, while traveling. (And in which case, if the internet is down, you can't access it anyways.) But I'm struggling to understand why you'd ever want to enable MFA for signing into a device on your LAN. If it's on your LAN, you probably have physical access to it, and that's basically a factor in itself. Not "something you have", but "where you are" (or I guess it is "something you have" -- the device itself). I've only encountered MFA before as something to protect remote account access. None of my other local devices support MFA -- I don't use it to unlock my phone, or my encrypted hard drive. So supporting it for local NAS access seems a bit unexpected.
- deleted 3y ago
  [deleted]
- KeepFlying 3y ago
  For a home network I think I agree with you, but in a corporate or SOHO environment there may be an open WiFi that requires at least some access to the server locked in the closet. You can't necessarily trust that people who have access to to the network should have full access to the server. Add thats before accounting for "defense in depth" approaches.
- velcrovan 3y ago
  Lots of companies do in fact treat MFA this way. Microsoft's AAD^H^H^H sorry, Entra ID has conditional access rules that forgo the need for MFA when signing in from known locations, and lots of companies make use of that. But it's becoming more and more popular, and in many cases necessary, to adopt a "zero-trust" approach to all devices no matter where they are located. That login attempt coming from your office LAN — how do you know it isn't an automated request from a compromised device? If you are enough of a high-value target, do you think it's inconceivable that someone might try and hop on your wifi network from the parking lot?
  - NoMoreNicksLeft 3y ago
applied_heat 3y ago
Bank of New Zealand and Canadian government both issue a 4x4 grid of three character codes and ask for some of them when I login to online services, this proves the “something I physically have” component of the authentication. I have the grid either on a card or printed off. I like that it doesn’t depend on a phone.
- velcrovan 3y ago
  Unfortunately the thing they gave you is static and easily reproducible. If infinitely many copies can be made by someone snapping a photo, then the "something you physically have" is no more secure than a second password you have written on a piece of paper.
  - applied_heat 3y ago
    If someone breaks in to the locked filing cabinet in my house I have bigger problems than 1 factor being compromised
- doubled112 3y ago
  Meanwhile, I put the grid in my password manager because I'll never find that paper. Defeats the purpose? Only kind of.
- pid-1 3y ago
  I've seen some investment banks provide a small device that looks like a calculator and generate MFA codes. Not sure what they are called.
  - wlesieutre 3y ago
    RSA SecurID tokens?
  - fergbrain 3y ago
    Barclays calls it a PINsentry card reader
  - 3y ago
verall 3y ago
I had this router and it had issues passing data through the ethernet ports at gigabit speed. It would cap between 500-600mbps. I turned off all of the intrusion detection, monitoring, parental control, etc services and it didn't fix anything. I had (2 PCs)<->DumbSwitch<->rt2600ac<->(3rd PC) The PCs connected to the dumb switch could communicate at gigabit but anything that went through the rt2600ac was limited, very frustrating. Running a long cable from 3rd PC to the $20 dumb switch fixed it. Eventually just gave up and use google fibers stupid dot router/WAP which I hate but at least it works. The dual WAN on the synology was nice though.
- Marsymars 3y ago
  > The dual WAN on the synology was nice though. If you only need the dual WAN for a lowish-bandwidth backup connection, Eero’s implementation works well enough, though does have some limitations. (Requires a subscription, only does backup over wi-fi.)
NKosmatos 3y ago
This needs a 2021 in the title.

60 points by alexfromapex 3y ago

I can think of many reasons not to use a Synology router, and this is one of them. Other ones: * Depending on your settings they broadcast an IPv6 DNS when they shouldn't. I told them about the bug and they scoffed. * Wrong setting when you DO broadcast an IPv6 DNS with just SLAAC. They send it via DHCPv6 without setting the right bits. * Setting up 2 networks with 2 domains, like iot.wirelessgigabit.com & home.wirelessgigabit.com does not work. They don't attach the domain to the the network. Last one wins. * No way of redirecting traffic, like all outgoing :53 to a port. All you can do is block which breaks things like a Google Mini. * No WireGuard VPN * No OIDC authentication. (DSM has it but for some arcane reason you need to join the domain before OIDC works...)

michael_michael 3y ago

MFA for my Synology failed recently because (I suspect) I let the drive go unused for a while and it lost sync with the time server. So all one time passwords my password manager generated were "wrong". Off in time by some unknown amount. No way to fix it, since I would need MFA to log in and fix it anyway. I had to reset the administrative UI and lose my user settings/admin preferences, but it did hang on to the data on the drives, luckily.

antsar 3y ago
Experienced this too. Having SSH access enabled on the Synology saved the day. There's no 2FA prompt on SSH, so you can SSH in and manually fix the time.
- naasking 3y ago
  Old tricks are the best tricks!
- olyjohn 3y ago
  Kinda defeats the whole point of MFA if you can just bypass it like that.
  - TrickardRixx 3y ago
    If the SSH key is password-protected, then SSH access is MFA.
    - doubled112 3y ago
      My SSH key is on a YubiKey. How many factors is that?
      - eli 3y ago
        1 if it isn't password protected and 2 if it is
    - olyjohn 3y ago
      Not sure that's true... If the key gets compromised, having it password protected does nothing.
      - password4321 3y ago
        > If the key gets compromised, having it password protected does nothing I apologize for my ignorance in advance: having a private key file password-protected does nothing? I guess I'm not understanding what you mean by "compromised"?
        olyjohn 3y ago
        Compromised, meaning someone has the key in an unprotected format, or they somehow got your password. Say someone manages to MITM you somehow and get your password to the file, or they manage to crack it, or phish it out of you. Then they can just take the key and use it freely to log into your things. With MFA, there's no way that any key can be used to log in as long as the other factor exists. If you have to push OK on your cell phone to log in for example, the key is useless without physical access to your phone. I'm not saying the password protection does nothing, it makes the key harder to crack but it's not another factor. It's simply an extension of the existing key. In other words, it's just a longer password.

blkhawk 3y ago

huh - normally there should be a set of "one use" codes for exactly this scenario.

crazygringo 3y ago
Yeah it's weird they don't: https://kb.synology.com/en-ca/DSM/help/DSM/SecureSignIn/2factor_authentication?version=7 https://kb.synology.com/en-ca/DSM/help/DSM/SecureSignIn/2fac... They support a backup e-mail address that it will send a verification code to if you lose your 2FA device. But, whoops -- that's not gonna work if it can't connect to the internet.

RedShift1 3y ago

MFA always feels like such a kludge... Do we really have no better ideas to solve this?

whizzter 3y ago
There's an RFC for a standard that I believe the Google Authenticator uses (and other authenticators also?). Basically (if I've understood it correctly), You get an random seed that you initiate the authenticator with, then for (each minute?) it combines the unix timestamp, the seed and calculate the time-based-one-time-password. So combining a user-specific password, the TOTP (whose seed is on an initiated device for the user) you have 2 factors that can be hard for an attacker to retrieve both of. https://datatracker.ietf.org/doc/html/rfc6238 https://datatracker.ietf.org/doc/html/rfc6238 (Kludgy? Maybe a bit but feels fairly secure in practice)
- oldbbsnickname 3y ago
  HOTP (one-time) and TOTP are typically used in conjunction with one another. HOTP provide backup codes should client or server time be out of sync. https://www.rfc-editor.org/rfc/rfc4226 https://www.rfc-editor.org/rfc/rfc4226 FIDO2 with a hardware key source provides a much stronger and more secure guarantee than a 6 digit hash and an unencrypted symmetric secret stored in an app. https://fidoalliance.org/fido2/ https://fidoalliance.org/fido2/ Any and all 2FA approaches demand backup codes (and backup code management with confidentiality and durability) to protect against 2FA loss or inability of the 2FA to function. For example, there are some apps that insist on performing FIDO2 on a non-NFC platform. While I can use a Lightning to USB-C adapter to workaround this limitation, it's possible that I might not have it and would need some other 2FA "sufficient" mechanism. By the way, there is "HSM"-like passkey functionality embedded in most modern Apple and Samsung devices that doesn't require a USB token. This has the downside of not being a dedicated hardware token, so it cannot be physically isolated offline and requires an additional piece of software to act as a FIDO2 authenticator.
  - lll-o-lll 3y ago
    What sucks is that password’s don’t need to be so insecure. If you took WebAuthn and, instead of the private key, used one password, it’d be nearly as strong. Assuming that one password is sufficiently strong, and the password input could not be intercepted, and no one ever looked over your shoulder, or used a camera, and you never wrote it down somewhere others can find it, and you never typed it where someone had installed a key logger… Actually, let’s bring on the passkeys.

wiml 3y ago

tldr: TOTP doesn't work if one device doesn't know what time it is.

crazygringo 3y ago

Genuine question: does MFA conceptually make any sense for a device on your local network, accessed locally? I understand why you'd want it if trying to access your NAS from the internet, while traveling. (And in which case, if the internet is down, you can't access it anyways.) But I'm struggling to understand why you'd ever want to enable MFA for signing into a device on your LAN. If it's on your LAN, you probably have physical access to it, and that's basically a factor in itself. Not "something you have", but "where you are" (or I guess it is "something you have" -- the device itself). I've only encountered MFA before as something to protect remote account access. None of my other local devices support MFA -- I don't use it to unlock my phone, or my encrypted hard drive. So supporting it for local NAS access seems a bit unexpected.

deleted 3y ago
[deleted]
KeepFlying 3y ago
For a home network I think I agree with you, but in a corporate or SOHO environment there may be an open WiFi that requires at least some access to the server locked in the closet. You can't necessarily trust that people who have access to to the network should have full access to the server. Add thats before accounting for "defense in depth" approaches.
velcrovan 3y ago
Lots of companies do in fact treat MFA this way. Microsoft's AAD^H^H^H sorry, Entra ID has conditional access rules that forgo the need for MFA when signing in from known locations, and lots of companies make use of that. But it's becoming more and more popular, and in many cases necessary, to adopt a "zero-trust" approach to all devices no matter where they are located. That login attempt coming from your office LAN — how do you know it isn't an automated request from a compromised device? If you are enough of a high-value target, do you think it's inconceivable that someone might try and hop on your wifi network from the parking lot?
- NoMoreNicksLeft 3y ago

applied_heat 3y ago

Bank of New Zealand and Canadian government both issue a 4x4 grid of three character codes and ask for some of them when I login to online services, this proves the “something I physically have” component of the authentication. I have the grid either on a card or printed off. I like that it doesn’t depend on a phone.

velcrovan 3y ago
Unfortunately the thing they gave you is static and easily reproducible. If infinitely many copies can be made by someone snapping a photo, then the "something you physically have" is no more secure than a second password you have written on a piece of paper.
- applied_heat 3y ago
  If someone breaks in to the locked filing cabinet in my house I have bigger problems than 1 factor being compromised
doubled112 3y ago
Meanwhile, I put the grid in my password manager because I'll never find that paper. Defeats the purpose? Only kind of.
pid-1 3y ago
I've seen some investment banks provide a small device that looks like a calculator and generate MFA codes. Not sure what they are called.
- wlesieutre 3y ago
  RSA SecurID tokens?
- fergbrain 3y ago
  Barclays calls it a PINsentry card reader
- 3y ago

verall 3y ago

I had this router and it had issues passing data through the ethernet ports at gigabit speed. It would cap between 500-600mbps. I turned off all of the intrusion detection, monitoring, parental control, etc services and it didn't fix anything. I had (2 PCs)<->DumbSwitch<->rt2600ac<->(3rd PC) The PCs connected to the dumb switch could communicate at gigabit but anything that went through the rt2600ac was limited, very frustrating. Running a long cable from 3rd PC to the $20 dumb switch fixed it. Eventually just gave up and use google fibers stupid dot router/WAP which I hate but at least it works. The dual WAN on the synology was nice though.

Marsymars 3y ago
> The dual WAN on the synology was nice though. If you only need the dual WAN for a lowish-bandwidth backup connection, Eero’s implementation works well enough, though does have some limitations. (Requires a subscription, only does backup over wi-fi.)

NKosmatos 3y ago

This needs a 2021 in the title.