9 ms·

I disagree with you - security is important at all layers of the stack. Right now, your mobile phone will connect to fake towers (Stingray). This means that SM

I disagree with you - security is important at all layers of the stack. Right now, your mobile phone will connect to fake towers (Stingray). This means that SMS 2FA codes can be intercepted to you, I believe. https://nakedsecurity.sophos.com/2018/04/06/washington-dc-awash-with-fake-cell-towers/ https://nakedsecurity.sophos.com/2018/04/06/washington-dc-aw...

silvestrov 8y ago
No, the problem is that the SMS standard was never updated with an encrypted version. Apple didn't want to open iMessage to the world. EU/USA should enforce a common, secure method for sending text messages to mobiles.
- simias 8y ago
  I agree with your main point but I feel like SMS is going to remain cleartext forever. It's basically like email (it's not like encrypted email formats ever gained mainstream traction). Besides I can't really imagine the EU/USA pushing for end-to-end SMS encryption. Fortunately as data plans get cheaper we have plenty of alternatives for encrypted messaging on smartphones.
  - dbdjfjrjvebd 8y ago
    Didn't the UK prevent SMS encryption when the standard was developed?
- wyldfire 8y ago
  > EU/USA should enforce a common, secure method for sending text messages to mobiles. No way do we want any regulation here! I will accept balkanization of messaging apps for the lack of government interference here. If a government messaging standard is introduced, it will absolutely be designed to consider lawful intercepts like US CALEA. It would be a key escrow system upon inception. EDIT: downvoters, join the debate. Do you feel differently? If so, why?
  - romshark 8y ago
    Shouldn't such old standards like SMS just die? I didn't write or receive any SMS for like 5 years now (except some confirmation codes) since encrypted messengers became so common and accessible. I think it's obvious that SMS is outdated either way and I too think that encryption should be P2P on the "application layer" for many reasons. Encrypting the actual physical transport would add extra cost in terms of latency and hardware and could become a maintenance disaster over time if I'm not mistaking.
  - toomuchtodo 8y ago
    I downvoted you because you show disdain regulation but it is clear the marketplace for a secure, unified messaging solution has failed. EU regulation of the telcom sector has proven effective in protecting consumers from poor decisions (such as exorbitant roaming fees). Regulation should not be the first option, but the last, and it is clear it is the only solution left in this regard.
    - wyldfire 8y ago
      It's not a general disdain but IMO here it makes sense. Has it really failed though?
      - toomuchtodo 8y ago
        Do we have secure SMS messages? Do we have unified mobile messaging with a mature protocol that is both widely accessible as well as secure? How many more decades shall we wait? (asked rhetorically, yet politely) Yes, I argue it has failed, and an SMS/MMS successor would look like a descendent of iMessages and Google's RCS. iMessages supports CALEA (but is still end to end encrypted, as well as FaceTime), all US messaging products must support it (even Twilio supports it [1] [2]). You are unable to subvert nation state legal jurisdictions within fundamental telcom infrastructure. Signal can get away with it, Apple, Google, and cellular carriers cannot. Can't have your cake (universal messaging) and eat it (end to end encryption with zero trust requirement) too. So can't we push from something better than SMS, using regulation if required? It must not be perfect, but simply extensible in the future (similar to SS7). In jurisdictions that are favorable to it, you support E2E encryption. In those that are not, you downgrade loudly. Compromises must occasionally be made. [1] https://www.twilio.com/legal/law-enforcement-guidelines https://www.twilio.com/legal/law-enforcement-guidelines [2] https://support.twilio.com/hc/en-us/articles/223136547-Submitting-subpoenas-court-orders-or-other-official-legal-requests-to-Twilio https://support.twilio.com/hc/en-us/articles/223136547-Submi...
repomies68 8y ago
Seriously? The problem is using SMS for anything where security is needed. SMS is garbage, don't use it for 2fa.
- remcob 8y ago
  Is there court precedence of a vendor (for example a bank) being held responsible for customer loss due to relying on SMS for 2FA? The insecurity of SMS needs to have way more awareness and vendors need to feel it in their pockets for this to improve. There are better alternatives like TOTP.
mikeash 8y ago
Consider a world where the cellular data protocol is totally secure and nothing else changes. Your SMS 2FA codes can still be intercepted by your service provider and anyone else who handles the message before it gets to them. Now consider a world where SMS is end-to-end encrypted. Nobody can intercept your 2FA codes, no matter how insecure the transport is.
- ethbro 8y ago
  End-to-end encryption doesn't solve your problem when the attacker is your first link network provider, without out-of-band signaling. Which I believe was parent's point. Attestation and authentication of network infrastructure (in a way that would preclude Stingray attacks) is equally important as anything you layer on top. Otherwise, without some sort of global PKI you can consult out of band, you're just rolling the dice that the cellular station you're connecting to isn't rogue and performing a man in the middle attack.
  - philsnow 8y ago
    If you have to trust your first network hop, then the "ends" of your "end to end" encryption are not the actual ends. The trust boundary needs to be pushed all the way up into the application on both sides. Some sort of global PKI like what iMessage uses under the covers?
  - mikeash 8y ago
    Without some sort of global PKI, how do you know your data connection actually goes to your cell provider?
    - ethbro 8y ago
      I assume the way most embedded devices guarantee security for their limited number of use cases -- pre-seed trusted root keys in hardware + validate signing against them when connecting. My point was that app-layer security magic doesn't mean much if your first network step is "connect to closest, highest power base station and implicitly trust it." There are wonderful things we can do on top of lower layer protocols, but the lower layers are pretty damn important too.
gnopgnip 8y ago
But if you visit an HTTPS website via a fake tower your connection is still secure
- zamadatix 8y ago
  Assuming there is never a vulnerability in the HTTPS implementation on the server/client. In reality there are.
tptacek 8y ago
No, you're not reasoning through this all the way. Yes, SS7 vulnerabilities mean that SMS 2FA codes can be captured. But that's not an argument for improving SS7; it's an argument for not trusting SS7 in the first place, and modern 2FA systems don't. Even if you "fixed" SS7, you'd still have to trust the phone companies with part of your authentication to unrelated third-party services.
- Alex3917 8y ago
  > modern 2FA systems don't Sure, if you're defining 'modern' as something other than what's actually used by the vast majority 2FA users. Even for people who use U2F or TOTP as their primary Gmail 2FA, what percentage do you think have actually correctly deleted their phone numbers from both their primary account and any recovery accounts? I have no idea, but I'm guessing less than 1%.
  - tedunangst 8y ago
    Not sure why there's such a hang up on prevalent vs modern. Yes, sms is prevalent. That doesn't make it modern.
    - kuwze 8y ago
      Next you’ll tell me email isn’t encrypted.
      - squirrelicus 8y ago
        Poe's law is biting me.
fooker 8y ago
Making all layers secure is just an exercise in redundancy.

silvestrov 8y ago

No, the problem is that the SMS standard was never updated with an encrypted version. Apple didn't want to open iMessage to the world. EU/USA should enforce a common, secure method for sending text messages to mobiles.

simias 8y ago
I agree with your main point but I feel like SMS is going to remain cleartext forever. It's basically like email (it's not like encrypted email formats ever gained mainstream traction). Besides I can't really imagine the EU/USA pushing for end-to-end SMS encryption. Fortunately as data plans get cheaper we have plenty of alternatives for encrypted messaging on smartphones.
- dbdjfjrjvebd 8y ago
  Didn't the UK prevent SMS encryption when the standard was developed?
wyldfire 8y ago
> EU/USA should enforce a common, secure method for sending text messages to mobiles. No way do we want any regulation here! I will accept balkanization of messaging apps for the lack of government interference here. If a government messaging standard is introduced, it will absolutely be designed to consider lawful intercepts like US CALEA. It would be a key escrow system upon inception. EDIT: downvoters, join the debate. Do you feel differently? If so, why?
- romshark 8y ago
  Shouldn't such old standards like SMS just die? I didn't write or receive any SMS for like 5 years now (except some confirmation codes) since encrypted messengers became so common and accessible. I think it's obvious that SMS is outdated either way and I too think that encryption should be P2P on the "application layer" for many reasons. Encrypting the actual physical transport would add extra cost in terms of latency and hardware and could become a maintenance disaster over time if I'm not mistaking.
- toomuchtodo 8y ago
  I downvoted you because you show disdain regulation but it is clear the marketplace for a secure, unified messaging solution has failed. EU regulation of the telcom sector has proven effective in protecting consumers from poor decisions (such as exorbitant roaming fees). Regulation should not be the first option, but the last, and it is clear it is the only solution left in this regard.
  - wyldfire 8y ago
    It's not a general disdain but IMO here it makes sense. Has it really failed though?
    - toomuchtodo 8y ago
      Do we have secure SMS messages? Do we have unified mobile messaging with a mature protocol that is both widely accessible as well as secure? How many more decades shall we wait? (asked rhetorically, yet politely) Yes, I argue it has failed, and an SMS/MMS successor would look like a descendent of iMessages and Google's RCS. iMessages supports CALEA (but is still end to end encrypted, as well as FaceTime), all US messaging products must support it (even Twilio supports it [1] [2]). You are unable to subvert nation state legal jurisdictions within fundamental telcom infrastructure. Signal can get away with it, Apple, Google, and cellular carriers cannot. Can't have your cake (universal messaging) and eat it (end to end encryption with zero trust requirement) too. So can't we push from something better than SMS, using regulation if required? It must not be perfect, but simply extensible in the future (similar to SS7). In jurisdictions that are favorable to it, you support E2E encryption. In those that are not, you downgrade loudly. Compromises must occasionally be made. [1] https://www.twilio.com/legal/law-enforcement-guidelines https://www.twilio.com/legal/law-enforcement-guidelines [2] https://support.twilio.com/hc/en-us/articles/223136547-Submitting-subpoenas-court-orders-or-other-official-legal-requests-to-Twilio https://support.twilio.com/hc/en-us/articles/223136547-Submi...

repomies68 8y ago

Seriously? The problem is using SMS for anything where security is needed. SMS is garbage, don't use it for 2fa.

remcob 8y ago
Is there court precedence of a vendor (for example a bank) being held responsible for customer loss due to relying on SMS for 2FA? The insecurity of SMS needs to have way more awareness and vendors need to feel it in their pockets for this to improve. There are better alternatives like TOTP.

mikeash 8y ago

Consider a world where the cellular data protocol is totally secure and nothing else changes. Your SMS 2FA codes can still be intercepted by your service provider and anyone else who handles the message before it gets to them. Now consider a world where SMS is end-to-end encrypted. Nobody can intercept your 2FA codes, no matter how insecure the transport is.

ethbro 8y ago
End-to-end encryption doesn't solve your problem when the attacker is your first link network provider, without out-of-band signaling. Which I believe was parent's point. Attestation and authentication of network infrastructure (in a way that would preclude Stingray attacks) is equally important as anything you layer on top. Otherwise, without some sort of global PKI you can consult out of band, you're just rolling the dice that the cellular station you're connecting to isn't rogue and performing a man in the middle attack.
- philsnow 8y ago
  If you have to trust your first network hop, then the "ends" of your "end to end" encryption are not the actual ends. The trust boundary needs to be pushed all the way up into the application on both sides. Some sort of global PKI like what iMessage uses under the covers?
- mikeash 8y ago
  Without some sort of global PKI, how do you know your data connection actually goes to your cell provider?
  - ethbro 8y ago
    I assume the way most embedded devices guarantee security for their limited number of use cases -- pre-seed trusted root keys in hardware + validate signing against them when connecting. My point was that app-layer security magic doesn't mean much if your first network step is "connect to closest, highest power base station and implicitly trust it." There are wonderful things we can do on top of lower layer protocols, but the lower layers are pretty damn important too.

gnopgnip 8y ago

But if you visit an HTTPS website via a fake tower your connection is still secure

zamadatix 8y ago
Assuming there is never a vulnerability in the HTTPS implementation on the server/client. In reality there are.

tptacek 8y ago

No, you're not reasoning through this all the way. Yes, SS7 vulnerabilities mean that SMS 2FA codes can be captured. But that's not an argument for improving SS7; it's an argument for not trusting SS7 in the first place, and modern 2FA systems don't. Even if you "fixed" SS7, you'd still have to trust the phone companies with part of your authentication to unrelated third-party services.

Alex3917 8y ago
> modern 2FA systems don't Sure, if you're defining 'modern' as something other than what's actually used by the vast majority 2FA users. Even for people who use U2F or TOTP as their primary Gmail 2FA, what percentage do you think have actually correctly deleted their phone numbers from both their primary account and any recovery accounts? I have no idea, but I'm guessing less than 1%.
- tedunangst 8y ago
  Not sure why there's such a hang up on prevalent vs modern. Yes, sms is prevalent. That doesn't make it modern.
  - kuwze 8y ago
    Next you’ll tell me email isn’t encrypted.
    - squirrelicus 8y ago
      Poe's law is biting me.

fooker 8y ago

Making all layers secure is just an exercise in redundancy.